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Change the PerfMap crst into an UNSAFE_ANYMODE crst#129021

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davidwrighton merged 8 commits into from
Jun 8, 2026
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Change the PerfMap crst into an UNSAFE_ANYMODE crst #129021

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Add logic to handle some simple cases where moving to preemptive is m…
davidwrighton Jun 4, 2026
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95630a4
Add feature to disable reporting of stubs via PerfMap
davidwrighton Jun 5, 2026
fa3cfe6
Reverse polarity of new flag
davidwrighton Jun 5, 2026
2f6a3cd
And update env flag doc in clrconfigvalues.h
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2 changes: 1 addition & 1 deletion src/coreclr/inc/clrconfigvalues.h
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Expand Up@@ -433,7 +433,7 @@ RETAIL_CONFIG_STRING_INFO(UNSUPPORTED_ETW_ObjectAllocationEventsPerTypePerSec, W
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapEnabled, W("PerfMapEnabled"), 0, "This flag is used on Linux and macOS to enable writing /tmp/perf-$pid.map. It is disabled by default")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapIgnoreSignal, W("PerfMapIgnoreSignal"), 0, "When perf map is enabled, this option will configure the specified signal to be accepted and ignored as a marker in the perf logs. It is disabled by default")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapShowOptimizationTiers, W("PerfMapShowOptimizationTiers"), 1, "Shows optimization tiers in the perf map for methods, as part of the symbol name. Useful for seeing separate stack frames for different optimization tiers of each method.")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapStubGranularity, W("PerfMapStubGranularity"), 0, "Report stubs with varying amounts of granularity (low bit being zero indicates attempt to group all stubs of a type together) (second lowest bit being non-zero records stubs at individual allocation sites, which is more expensive, but also more accurate).")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapStubGranularity, W("PerfMapStubGranularity"), 0, "Report stubs with varying amounts of granularity (low bit being zero indicates attempt to group all stubs of a type together) (second lowest bit being non-zero records stubs at individual allocation sites, which is more expensive, but also more accurate) (third lowest bit disables stub logging).")
#endif

RETAIL_CONFIG_STRING_INFO(EXTERNAL_StartupDelayMS, W("StartupDelayMS"), "")
Expand Down
6 changes: 5 additions & 1 deletion src/coreclr/vm/eventing/eventpipe/ds-rt-coreclr.h
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Expand Up@@ -233,7 +233,11 @@ static
uint32_t
ds_rt_enable_perfmap (uint32_t type)
{
LIMITED_METHOD_CONTRACT;
CONTRACTL
{
MODE_PREEMPTIVE;
}
CONTRACTL_END;

#ifdef FEATURE_PERFMAP
PerfMap::PerfMapType perfMapType = (PerfMap::PerfMapType)type;
Expand Down
40 changes: 31 additions & 9 deletions src/coreclr/vm/perfmap.cpp
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Expand Up@@ -33,6 +33,7 @@ PerfMap * PerfMap::s_Current = nullptr;
bool PerfMap::s_ShowOptimizationTiers = false;
bool PerfMap::s_GroupStubsOfSameType = false;
bool PerfMap::s_IndividualAllocationStubReporting = false;
bool PerfMap::s_LogStubs = false;

unsigned PerfMap::s_StubsMapped = 0;
CrstStatic PerfMap::s_csPerfMap;
Expand All@@ -47,7 +48,15 @@ void PerfMap::Initialize()
{
LIMITED_METHOD_CONTRACT;

s_csPerfMap.Init(CrstPerfMap);
// Use CRST_UNSAFE_ANYMODE to avoid a GC-mode toggle deadlock: callers such as
// CodeFragmentHeap::RealAllocAlignedMem hold CRST_UNSAFE_ANYMODE locks in cooperative
// mode. A default Crst here would toggle cooperative->preemptive->acquire->cooperative,
// and the post-acquire DisablePreemptiveGC can block on a pending GC suspension,
// forming a deadlock cycle with threads waiting on the outer UNSAFE_ANYMODE lock.
// All data accessed under this lock is native (FILE*, fd, SString) so holding it
// in cooperative mode does not introduce new GC-safety issues. Doing I/O
// in cooperative mode is still less than ideal.
s_csPerfMap.Init(CrstPerfMap, CrstFlags(CRST_UNSAFE_ANYMODE));

PerfMapType perfMapType = (PerfMapType)CLRConfig::GetConfigValue(CLRConfig::EXTERNAL_PerfMapEnabled);
PerfMap::Enable(perfMapType, false);
Expand DownExpand Up@@ -77,11 +86,16 @@ void PerfMap::InitializeConfiguration()
DWORD granularity = CLRConfig::GetConfigValue(CLRConfig::EXTERNAL_PerfMapStubGranularity);
s_GroupStubsOfSameType = (granularity & 1) != 1;
s_IndividualAllocationStubReporting = (granularity & 2) != 0;
s_LogStubs = (granularity & 4) == 0;
}
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void PerfMap::Enable(PerfMapType type, bool sendExisting)
{
LIMITED_METHOD_CONTRACT;
CONTRACTL
{
MODE_PREEMPTIVE;
}
CONTRACTL_END;

if (type == PerfMapType::DISABLED)
{
Expand DownExpand Up@@ -294,8 +308,6 @@ void PerfMap::WriteLine(SString& line)

void PerfMap::LogJITCompiledMethod(MethodDesc * pMethod, PCODE pCode, size_t codeSize, PrepareCodeConfig *pConfig)
{
LIMITED_METHOD_CONTRACT;

CONTRACTL{
THROWS;
GC_NOTRIGGER;
Expand DownExpand Up@@ -349,7 +361,12 @@ void PerfMap::LogJITCompiledMethod(MethodDesc * pMethod, PCODE pCode, size_t cod
// Log a pre-compiled method to the perfmap.
void PerfMap::LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)
{
LIMITED_METHOD_CONTRACT;
CONTRACTL
{
THROWS;
MODE_PREEMPTIVE;
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}
CONTRACTL_END;

if (!s_enabled)
{
Expand DownExpand Up@@ -385,14 +402,14 @@ void PerfMap::LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)

if (methodRegionInfo.coldSize > 0)
{
CrstHolder ch(&(s_csPerfMap));

if (s_ShowOptimizationTiers)
{
pMethod->GetFullMethodInfo(name);
name.Append(W("[PreJit-cold]"));
}

CrstHolder ch(&(s_csPerfMap));
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PAL_PerfJitDump_LogMethod((void*)methodRegionInfo.coldStartAddress, methodRegionInfo.coldSize, name.GetUTF8(), nullptr, nullptr, /*reportCodeBlock*/true);
}
}
Expand All@@ -402,9 +419,14 @@ void PerfMap::LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)
// Log a set of stub to the map.
void PerfMap::LogStubs(const char* stubType, const char* stubOwner, PCODE pCode, size_t codeSize, PerfMapStubType stubAllocationType)
{
LIMITED_METHOD_CONTRACT;
CONTRACTL
{
GC_NOTRIGGER;
MODE_ANY;
}
CONTRACTL_END;

if (!s_enabled)
if (!s_enabled || !s_LogStubs)
{
return;
}
Expand Down
48 changes: 48 additions & 0 deletions src/coreclr/vm/perfmap.h
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Expand Up@@ -19,6 +19,52 @@ enum class PerfMapStubType
Individual
};

#ifndef FEATURE_PERFMAP

class PerfMap
{
public:
static bool IsEnabled()
{
#ifdef DEBUG
return true;
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#else
return false;
#endif
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}
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static void LogJITCompiledMethod(MethodDesc * pMethod, PCODE pCode, size_t codeSize, PrepareCodeConfig *pConfig)
{
CONTRACTL
{
THROWS;
MODE_PREEMPTIVE;
}
CONTRACTL_END;
}

static void LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)
{
CONTRACTL
{
THROWS;
MODE_PREEMPTIVE;
}
CONTRACTL_END;
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}

static void LogStubs(const char* stubType, const char* stubOwner, PCODE pCode, size_t codeSize, PerfMapStubType stubAllocationType)
{
CONTRACTL
{
GC_NOTRIGGER;
MODE_ANY;
}
CONTRACTL_END;
}
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};

#else // FEATURE_PERFMAP

class PerfMap
{
private:
Expand All@@ -36,6 +82,7 @@ class PerfMap
// Indicate current stub granularity rules
static bool s_GroupStubsOfSameType;
static bool s_IndividualAllocationStubReporting;
static bool s_LogStubs; // If false, do not log stubs at all

// Set to true if an error is encountered when writing to the file.
static unsigned s_StubsMapped;
Expand DownExpand Up@@ -112,4 +159,5 @@ class PerfMap

static bool LowGranularityStubs() { return !s_IndividualAllocationStubReporting; }
};
#endif // FEATURE_PERFMAP
#endif // PERFPID_H
85 changes: 58 additions & 27 deletions src/coreclr/vm/virtualcallstub.cpp
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Expand Up@@ -10,9 +10,7 @@
#include "comdelegate.h"
#include <dn-stdio.h>

#ifdef FEATURE_PERFMAP
#include "perfmap.h"
#endif

#ifndef DACCESS_COMPILE

Expand DownExpand Up@@ -1051,7 +1049,19 @@ PCODE VirtualCallStubManager::GetCallStub(DispatchToken token)
{
if ((stub = (PCODE)(lookups->Find(&probeL))) == CALL_STUB_EMPTY_ENTRY)
{
LookupHolder *pLookupHolder = GenerateLookupStub(addrOfResolver, token.To_SIZE_T());
LookupHolder *pLookupHolder;
bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
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{
GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
pLookupHolder = GenerateLookupStub(addrOfResolver, token.To_SIZE_T());
}

if (reenteredCooperativeGCMode)
{
// The prober may have been invalidated by reentering cooperative GC mode, reset it
BOOL success = lookups->SetUpProber(token.To_SIZE_T(), 0, &probeL);
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_ASSERTE(success);
}
stub = (PCODE) (lookups->Add((size_t)(pLookupHolder->stub()->entryPoint()), &probeL));
}
}
Expand DownExpand Up@@ -1082,7 +1092,20 @@ PCODE VirtualCallStubManager::GetVTableCallStub(DWORD slot)
{
if ((stub = (PCODE)(vtableCallers->Find(&probe))) == CALL_STUB_EMPTY_ENTRY)
{
VTableCallHolder *pHolder = GenerateVTableCallStub(slot);
VTableCallHolder *pHolder;

bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
{
GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
pHolder = GenerateVTableCallStub(slot);
}

if (reenteredCooperativeGCMode)
{
// The prober may have been invalidated by reentering cooperative GC mode, reset it
BOOL success = vtableCallers->SetUpProber(DispatchToken::CreateDispatchToken(slot).To_SIZE_T(), 0, &probe);
_ASSERTE(success);
}
stub = (PCODE)(vtableCallers->Add((size_t)(pHolder->stub()->entryPoint()), &probe));
}
}
Expand DownExpand Up@@ -1115,9 +1138,7 @@ VTableCallHolder* VirtualCallStubManager::GenerateVTableCallStub(DWORD slot)
LOG((LF_STUBS, LL_INFO10000, "GenerateVTableCallStub for slot " FMT_ADDR "at" FMT_ADDR "\n",
DBG_ADDR(slot), DBG_ADDR(pHolder->stub())));

#ifdef FEATURE_PERFMAP
PerfMap::LogStubs(__FUNCTION__, "GenerateVTableCallStub", (PCODE)pHolder->stub(), pHolder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

RETURN(pHolder);
}
Expand DownExpand Up@@ -2054,14 +2075,24 @@ PCODE VirtualCallStubManager::ResolveWorker(StubCallSite* pCallSite,
}
#endif // TARGET_X86 && !UNIX_X86_ABI

pResolveHolder = GenerateResolveStub(pResolverFcn,
pBackPatchFcn,
token.To_SIZE_T()
bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
{
GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
pResolveHolder = GenerateResolveStub(pResolverFcn,
pBackPatchFcn,
token.To_SIZE_T()
#if defined(TARGET_X86) && !defined(UNIX_X86_ABI)
, stackArgumentsSize
, stackArgumentsSize
#endif
);
}

if (reenteredCooperativeGCMode)
{
// The prober may have been invalidated by reentering cooperative GC mode, reset it
BOOL success = resolvers->SetUpProber(token.To_SIZE_T(), 0, &probeR);
_ASSERTE(success);
}
// Add the resolve entrypoint into the cache.
//@TODO: Can we store a pointer to the holder rather than the entrypoint?
resolvers->Add((size_t)(pResolveHolder->stub()->resolveEntryPoint()), &probeR);
Expand DownExpand Up@@ -2095,9 +2126,12 @@ PCODE VirtualCallStubManager::ResolveWorker(StubCallSite* pCallSite,
if (addrOfDispatch == CALL_STUB_EMPTY_ENTRY)
{
PCODE addrOfFail = pResolveHolder->stub()->failEntryPoint();
bool reenteredCooperativeGCMode = false;
pDispatchHolder = GenerateDispatchStub(
target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
{
GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
pDispatchHolder = GenerateDispatchStub(
target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
}
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if (reenteredCooperativeGCMode)
{
// The prober may have been invalidated by reentering cooperative GC mode, reset it
Expand DownExpand Up@@ -2208,9 +2242,12 @@ PCODE VirtualCallStubManager::ResolveWorker(StubCallSite* pCallSite,
// so we may have to create it now
ResolveHolder* pResolveHolder = ResolveHolder::FromResolveEntry(pCallSite->GetSiteTarget());
PCODE addrOfFail = pResolveHolder->stub()->failEntryPoint();
bool reenteredCooperativeGCMode = false;
pDispatchHolder = GenerateDispatchStub(
target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
{
GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
pDispatchHolder = GenerateDispatchStub(
target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
}
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if (reenteredCooperativeGCMode)
{
// The prober may have been invalidated by reentering cooperative GC mode, reset it
Expand DownExpand Up@@ -2799,7 +2836,6 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStub(PCODE ad
PRECONDITION(addrOfFail != NULL);
PRECONDITION(CheckPointer(pMTExpected));
PRECONDITION(pMayHaveReenteredCooperativeGCMode != nullptr);
PRECONDITION(!*pMayHaveReenteredCooperativeGCMode);
POSTCONDITION(CheckPointer(RETVAL));
} CONTRACT_END;

Expand DownExpand Up@@ -2862,9 +2898,7 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStub(PCODE ad
LOG((LF_STUBS, LL_INFO10000, "GenerateDispatchStub for token" FMT_ADDR "and pMT" FMT_ADDR "at" FMT_ADDR "\n",
DBG_ADDR(dispatchToken), DBG_ADDR(pMTExpected), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
PerfMap::LogStubs(__FUNCTION__, "GenerateDispatchStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

RETURN (holder);
}
Expand All@@ -2888,7 +2922,6 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStubLong(PCODE
PRECONDITION(addrOfFail != NULL);
PRECONDITION(CheckPointer(pMTExpected));
PRECONDITION(pMayHaveReenteredCooperativeGCMode != nullptr);
PRECONDITION(!*pMayHaveReenteredCooperativeGCMode);
POSTCONDITION(CheckPointer(RETVAL));
} CONTRACT_END;

Expand DownExpand Up@@ -2923,9 +2956,7 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStubLong(PCODE
LOG((LF_STUBS, LL_INFO10000, "GenerateDispatchStub for token" FMT_ADDR "and pMT" FMT_ADDR "at" FMT_ADDR "\n",
DBG_ADDR(dispatchToken), DBG_ADDR(pMTExpected), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
PerfMap::LogStubs(__FUNCTION__, "GenerateDispatchStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

RETURN (holder);
}
Expand DownExpand Up@@ -3021,9 +3052,7 @@ ResolveHolder *VirtualCallStubManager::GenerateResolveStub(PCODE addr
LOG((LF_STUBS, LL_INFO10000, "GenerateResolveStub for token" FMT_ADDR "at" FMT_ADDR "\n",
DBG_ADDR(dispatchToken), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
PerfMap::LogStubs(__FUNCTION__, "GenerateResolveStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

RETURN (holder);
}
Expand DownExpand Up@@ -3054,9 +3083,7 @@ LookupHolder *VirtualCallStubManager::GenerateLookupStub(PCODE addrOfResolver, s
LOG((LF_STUBS, LL_INFO10000, "GenerateLookupStub for token" FMT_ADDR "at" FMT_ADDR "\n",
DBG_ADDR(dispatchToken), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
PerfMap::LogStubs(__FUNCTION__, "GenerateLookupStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

RETURN (holder);
}
Expand DownExpand Up@@ -3084,8 +3111,12 @@ ResolveCacheElem *VirtualCallStubManager::GenerateResolveCacheElem(void *addrOfC
CONSISTENCY_CHECK(CheckPointer(pMTExpected));

//allocate from the requisite heap and set the appropriate fields
ResolveCacheElem *e = (ResolveCacheElem*) (void*)
ResolveCacheElem *e;
{
GCX_NOTRIGGER();
e = (ResolveCacheElem*) (void*)
cache_entry_heap->AllocAlignedMem(sizeof(ResolveCacheElem), CODE_SIZE_ALIGN);
}

e->pMT = pMTExpected;
e->token = token;
Expand Down
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Change the PerfMap crst into an UNSAFE_ANYMODE crst by davidwrighton · Pull Request #129021 · dotnet/runtime · GitHub
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Change the PerfMap crst into an UNSAFE_ANYMODE crst#129021

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 Merged

davidwrighton
merged 8 commits into

from

Jun 8, 2026
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Change the PerfMap crst into an UNSAFE_ANYMODE crst
#129021
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4f02657

Add logic to handle some simple cases where moving to preemptive is m…


davidwrighton Jun 4, 2026
4e4a6f6

Code review feedback


davidwrighton Jun 5, 2026
95630a4

Add feature to disable reporting of stubs via PerfMap


davidwrighton Jun 5, 2026
fa3cfe6

Reverse polarity of new flag


davidwrighton Jun 5, 2026
2f6a3cd

And update env flag doc in clrconfigvalues.h


davidwrighton Jun 5, 2026
3e68fd6

Apply suggestions from code review


davidwrighton Jun 8, 2026
2436293

Apply suggestion from @jkotas


jkotas Jun 8, 2026
1a6c35a

Apply suggestions from code review


jkotas Jun 8, 2026

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2 changes: 1 addition & 1 deletion
src/coreclr/inc/clrconfigvalues.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -433,7 +433,7 @@ RETAIL_CONFIG_STRING_INFO(UNSUPPORTED_ETW_ObjectAllocationEventsPerTypePerSec, W
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapEnabled, W("PerfMapEnabled"), 0, "This flag is used on Linux and macOS to enable writing /tmp/perf-$pid.map. It is disabled by default")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapIgnoreSignal, W("PerfMapIgnoreSignal"), 0, "When perf map is enabled, this option will configure the specified signal to be accepted and ignored as a marker in the perf logs. It is disabled by default")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapShowOptimizationTiers, W("PerfMapShowOptimizationTiers"), 1, "Shows optimization tiers in the perf map for methods, as part of the symbol name. Useful for seeing separate stack frames for different optimization tiers of each method.")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapStubGranularity, W("PerfMapStubGranularity"), 0, "Report stubs with varying amounts of granularity (low bit being zero indicates attempt to group all stubs of a type together) (second lowest bit being non-zero records stubs at individual allocation sites, which is more expensive, but also more accurate).")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapStubGranularity, W("PerfMapStubGranularity"), 0, "Report stubs with varying amounts of granularity (low bit being zero indicates attempt to group all stubs of a type together) (second lowest bit being non-zero records stubs at individual allocation sites, which is more expensive, but also more accurate) (third lowest bit disables stub logging).")
#endif

RETAIL_CONFIG_STRING_INFO(EXTERNAL_StartupDelayMS, W("StartupDelayMS"), "")
Expand Down

6 changes: 5 additions & 1 deletion
src/coreclr/vm/eventing/eventpipe/ds-rt-coreclr.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -233,7 +233,11 @@ static
uint32_t
ds_rt_enable_perfmap (uint32_t type)
{
	LIMITED_METHOD_CONTRACT;
 CONTRACTL
 {
 MODE_PREEMPTIVE;
 }
 CONTRACTL_END;

#ifdef FEATURE_PERFMAP
	PerfMap::PerfMapType perfMapType = (PerfMap::PerfMapType)type;
Expand Down

40 changes: 31 additions & 9 deletions
src/coreclr/vm/perfmap.cpp

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Original file line numberDiff line numberDiff line change
Expand Up@@ -33,6 +33,7 @@ PerfMap * PerfMap::s_Current = nullptr;
bool PerfMap::s_ShowOptimizationTiers = false;
bool PerfMap::s_GroupStubsOfSameType = false;
bool PerfMap::s_IndividualAllocationStubReporting = false;
bool PerfMap::s_LogStubs = false;

unsigned PerfMap::s_StubsMapped = 0;
CrstStatic PerfMap::s_csPerfMap;
Expand All@@ -47,7 +48,15 @@ void PerfMap::Initialize()
{
 LIMITED_METHOD_CONTRACT;

 s_csPerfMap.Init(CrstPerfMap);
 // Use CRST_UNSAFE_ANYMODE to avoid a GC-mode toggle deadlock: callers such as
 // CodeFragmentHeap::RealAllocAlignedMem hold CRST_UNSAFE_ANYMODE locks in cooperative
 // mode. A default Crst here would toggle cooperative->preemptive->acquire->cooperative,
 // and the post-acquire DisablePreemptiveGC can block on a pending GC suspension,
 // forming a deadlock cycle with threads waiting on the outer UNSAFE_ANYMODE lock.
 // All data accessed under this lock is native (FILE*, fd, SString) so holding it
 // in cooperative mode does not introduce new GC-safety issues. Doing I/O
 // in cooperative mode is still less than ideal.
 s_csPerfMap.Init(CrstPerfMap, CrstFlags(CRST_UNSAFE_ANYMODE));

 PerfMapType perfMapType = (PerfMapType)CLRConfig::GetConfigValue(CLRConfig::EXTERNAL_PerfMapEnabled);
 PerfMap::Enable(perfMapType, false);
Expand DownExpand Up@@ -77,11 +86,16 @@ void PerfMap::InitializeConfiguration()
 DWORD granularity = CLRConfig::GetConfigValue(CLRConfig::EXTERNAL_PerfMapStubGranularity);
 s_GroupStubsOfSameType = (granularity & 1) != 1;
 s_IndividualAllocationStubReporting = (granularity & 2) != 0;
 s_LogStubs = (granularity & 4) == 0;
}
Comment thread
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void PerfMap::Enable(PerfMapType type, bool sendExisting)
{
 LIMITED_METHOD_CONTRACT;
 CONTRACTL
 {
 MODE_PREEMPTIVE;
 }
 CONTRACTL_END;

 if (type == PerfMapType::DISABLED)
 {
Expand DownExpand Up@@ -294,8 +308,6 @@ void PerfMap::WriteLine(SString& line)

void PerfMap::LogJITCompiledMethod(MethodDesc * pMethod, PCODE pCode, size_t codeSize, PrepareCodeConfig *pConfig)
{
 LIMITED_METHOD_CONTRACT;

 CONTRACTL{
 THROWS;
 GC_NOTRIGGER;
Expand DownExpand Up@@ -349,7 +361,12 @@ void PerfMap::LogJITCompiledMethod(MethodDesc * pMethod, PCODE pCode, size_t cod
// Log a pre-compiled method to the perfmap.
void PerfMap::LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)
{
 LIMITED_METHOD_CONTRACT;
 CONTRACTL
 {
 THROWS;
 MODE_PREEMPTIVE;
Comment thread
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 }
 CONTRACTL_END;

 if (!s_enabled)
 {
Expand DownExpand Up@@ -385,14 +402,14 @@ void PerfMap::LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)

 if (methodRegionInfo.coldSize > 0)
 {
 CrstHolder ch(&(s_csPerfMap));

 if (s_ShowOptimizationTiers)
 {
 pMethod->GetFullMethodInfo(name);
 name.Append(W("[PreJit-cold]"));
 }

 CrstHolder ch(&(s_csPerfMap));
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 PAL_PerfJitDump_LogMethod((void*)methodRegionInfo.coldStartAddress, methodRegionInfo.coldSize, name.GetUTF8(), nullptr, nullptr, /*reportCodeBlock*/true);
 }
 }
Expand All@@ -402,9 +419,14 @@ void PerfMap::LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)
// Log a set of stub to the map.
void PerfMap::LogStubs(const char* stubType, const char* stubOwner, PCODE pCode, size_t codeSize, PerfMapStubType stubAllocationType)
{
 LIMITED_METHOD_CONTRACT;
 CONTRACTL
 {
 GC_NOTRIGGER;
 MODE_ANY;
 }
 CONTRACTL_END;

 if (!s_enabled)
 if (!s_enabled || !s_LogStubs)
 {
 return;
 }
Expand Down

48 changes: 48 additions & 0 deletions
src/coreclr/vm/perfmap.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -19,6 +19,52 @@ enum class PerfMapStubType
 Individual
};

#ifndef FEATURE_PERFMAP

class PerfMap
{
public:
 static bool IsEnabled()
 {
#ifdef DEBUG
 return true;
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#else
 return false;
#endif
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 }
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 static void LogJITCompiledMethod(MethodDesc * pMethod, PCODE pCode, size_t codeSize, PrepareCodeConfig *pConfig)
 {
 CONTRACTL
 {
 THROWS;
 MODE_PREEMPTIVE;
 }
 CONTRACTL_END;
 }

 static void LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)
 {
 CONTRACTL
 {
 THROWS;
 MODE_PREEMPTIVE;
 }
 CONTRACTL_END;
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 }

 static void LogStubs(const char* stubType, const char* stubOwner, PCODE pCode, size_t codeSize, PerfMapStubType stubAllocationType)
 {
 CONTRACTL
 {
 GC_NOTRIGGER;
 MODE_ANY;
 }
 CONTRACTL_END;
 }
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};

#else // FEATURE_PERFMAP

class PerfMap
{
private:
Expand All@@ -36,6 +82,7 @@ class PerfMap
 // Indicate current stub granularity rules
 static bool s_GroupStubsOfSameType;
 static bool s_IndividualAllocationStubReporting;
 static bool s_LogStubs; // If false, do not log stubs at all

 // Set to true if an error is encountered when writing to the file.
 static unsigned s_StubsMapped;
Expand DownExpand Up@@ -112,4 +159,5 @@ class PerfMap

 static bool LowGranularityStubs() { return !s_IndividualAllocationStubReporting; }
};
#endif // FEATURE_PERFMAP
#endif // PERFPID_H

85 changes: 58 additions & 27 deletions
src/coreclr/vm/virtualcallstub.cpp

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Original file line numberDiff line numberDiff line change
Expand Up@@ -10,9 +10,7 @@
#include "comdelegate.h"
#include <dn-stdio.h>

#ifdef FEATURE_PERFMAP
#include "perfmap.h"
#endif

#ifndef DACCESS_COMPILE

Expand DownExpand Up@@ -1051,7 +1049,19 @@ PCODE VirtualCallStubManager::GetCallStub(DispatchToken token)
 {
 if ((stub = (PCODE)(lookups->Find(&probeL))) == CALL_STUB_EMPTY_ENTRY)
 {
 LookupHolder *pLookupHolder = GenerateLookupStub(addrOfResolver, token.To_SIZE_T());
 LookupHolder *pLookupHolder;
 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
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 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pLookupHolder = GenerateLookupStub(addrOfResolver, token.To_SIZE_T());
 }

 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
 BOOL success = lookups->SetUpProber(token.To_SIZE_T(), 0, &probeL);
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 _ASSERTE(success);
 }
 stub = (PCODE) (lookups->Add((size_t)(pLookupHolder->stub()->entryPoint()), &probeL));
 }
 }
Expand DownExpand Up@@ -1082,7 +1092,20 @@ PCODE VirtualCallStubManager::GetVTableCallStub(DWORD slot)
 {
 if ((stub = (PCODE)(vtableCallers->Find(&probe))) == CALL_STUB_EMPTY_ENTRY)
 {
 VTableCallHolder *pHolder = GenerateVTableCallStub(slot);
 VTableCallHolder *pHolder;

 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pHolder = GenerateVTableCallStub(slot);
 }

 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
 BOOL success = vtableCallers->SetUpProber(DispatchToken::CreateDispatchToken(slot).To_SIZE_T(), 0, &probe);
 _ASSERTE(success);
 }
 stub = (PCODE)(vtableCallers->Add((size_t)(pHolder->stub()->entryPoint()), &probe));
 }
 }
Expand DownExpand Up@@ -1115,9 +1138,7 @@ VTableCallHolder* VirtualCallStubManager::GenerateVTableCallStub(DWORD slot)
 LOG((LF_STUBS, LL_INFO10000, "GenerateVTableCallStub for slot " FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(slot), DBG_ADDR(pHolder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateVTableCallStub", (PCODE)pHolder->stub(), pHolder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN(pHolder);
}
Expand DownExpand Up@@ -2054,14 +2075,24 @@ PCODE VirtualCallStubManager::ResolveWorker(StubCallSite* pCallSite,
 }
#endif // TARGET_X86 && !UNIX_X86_ABI

 pResolveHolder = GenerateResolveStub(pResolverFcn,
 pBackPatchFcn,
 token.To_SIZE_T()
 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pResolveHolder = GenerateResolveStub(pResolverFcn,
 pBackPatchFcn,
 token.To_SIZE_T()
#if defined(TARGET_X86) && !defined(UNIX_X86_ABI)
 , stackArgumentsSize
, stackArgumentsSize
#endif
 );
 }

 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
 BOOL success = resolvers->SetUpProber(token.To_SIZE_T(), 0, &probeR);
 _ASSERTE(success);
 }
 // Add the resolve entrypoint into the cache.
 //@TODO: Can we store a pointer to the holder rather than the entrypoint?
 resolvers->Add((size_t)(pResolveHolder->stub()->resolveEntryPoint()), &probeR);
Expand DownExpand Up@@ -2095,9 +2126,12 @@ PCODE VirtualCallStubManager::ResolveWorker(StubCallSite* pCallSite,
 if (addrOfDispatch == CALL_STUB_EMPTY_ENTRY)
 {
 PCODE addrOfFail = pResolveHolder->stub()->failEntryPoint();
 bool reenteredCooperativeGCMode = false;
 pDispatchHolder = GenerateDispatchStub(
 target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pDispatchHolder = GenerateDispatchStub(
 target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
 }
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 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
Expand DownExpand Up@@ -2208,9 +2242,12 @@ PCODE VirtualCallStubManager::ResolveWorker(StubCallSite* pCallSite,
 // so we may have to create it now
 ResolveHolder* pResolveHolder = ResolveHolder::FromResolveEntry(pCallSite->GetSiteTarget());
 PCODE addrOfFail = pResolveHolder->stub()->failEntryPoint();
 bool reenteredCooperativeGCMode = false;
 pDispatchHolder = GenerateDispatchStub(
 target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pDispatchHolder = GenerateDispatchStub(
 target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
 }
Comment thread
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 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
Expand DownExpand Up@@ -2799,7 +2836,6 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStub(PCODE ad
 PRECONDITION(addrOfFail != NULL);
 PRECONDITION(CheckPointer(pMTExpected));
 PRECONDITION(pMayHaveReenteredCooperativeGCMode != nullptr);
 PRECONDITION(!*pMayHaveReenteredCooperativeGCMode);
 POSTCONDITION(CheckPointer(RETVAL));
 } CONTRACT_END;

Expand DownExpand Up@@ -2862,9 +2898,7 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStub(PCODE ad
 LOG((LF_STUBS, LL_INFO10000, "GenerateDispatchStub for token" FMT_ADDR "and pMT" FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(dispatchToken), DBG_ADDR(pMTExpected), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateDispatchStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN (holder);
}
Expand All@@ -2888,7 +2922,6 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStubLong(PCODE
 PRECONDITION(addrOfFail != NULL);
 PRECONDITION(CheckPointer(pMTExpected));
 PRECONDITION(pMayHaveReenteredCooperativeGCMode != nullptr);
 PRECONDITION(!*pMayHaveReenteredCooperativeGCMode);
 POSTCONDITION(CheckPointer(RETVAL));
 } CONTRACT_END;

Expand DownExpand Up@@ -2923,9 +2956,7 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStubLong(PCODE
 LOG((LF_STUBS, LL_INFO10000, "GenerateDispatchStub for token" FMT_ADDR "and pMT" FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(dispatchToken), DBG_ADDR(pMTExpected), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateDispatchStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN (holder);
}
Expand DownExpand Up@@ -3021,9 +3052,7 @@ ResolveHolder *VirtualCallStubManager::GenerateResolveStub(PCODE addr
 LOG((LF_STUBS, LL_INFO10000, "GenerateResolveStub for token" FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(dispatchToken), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateResolveStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN (holder);
}
Expand DownExpand Up@@ -3054,9 +3083,7 @@ LookupHolder *VirtualCallStubManager::GenerateLookupStub(PCODE addrOfResolver, s
 LOG((LF_STUBS, LL_INFO10000, "GenerateLookupStub for token" FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(dispatchToken), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateLookupStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN (holder);
}
Expand DownExpand Up@@ -3084,8 +3111,12 @@ ResolveCacheElem *VirtualCallStubManager::GenerateResolveCacheElem(void *addrOfC
 CONSISTENCY_CHECK(CheckPointer(pMTExpected));

 //allocate from the requisite heap and set the appropriate fields
 ResolveCacheElem *e = (ResolveCacheElem*) (void*)
 ResolveCacheElem *e;
 {
 GCX_NOTRIGGER();
 e = (ResolveCacheElem*) (void*)
 cache_entry_heap->AllocAlignedMem(sizeof(ResolveCacheElem), CODE_SIZE_ALIGN);
 }

 e->pMT = pMTExpected;
 e->token = token;
Expand Down
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Change the PerfMap crst into an UNSAFE_ANYMODE crst by davidwrighton · Pull Request #129021 · dotnet/runtime · GitHub
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 Merged

davidwrighton
merged 8 commits into

from

Jun 8, 2026
 Merged


Change the PerfMap crst into an UNSAFE_ANYMODE crst
#129021
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4f02657

Add logic to handle some simple cases where moving to preemptive is m…


davidwrighton Jun 4, 2026
4e4a6f6

Code review feedback


davidwrighton Jun 5, 2026
95630a4

Add feature to disable reporting of stubs via PerfMap


davidwrighton Jun 5, 2026
fa3cfe6

Reverse polarity of new flag


davidwrighton Jun 5, 2026
2f6a3cd

And update env flag doc in clrconfigvalues.h


davidwrighton Jun 5, 2026
3e68fd6

Apply suggestions from code review


davidwrighton Jun 8, 2026
2436293

Apply suggestion from @jkotas


jkotas Jun 8, 2026
1a6c35a

Apply suggestions from code review


jkotas Jun 8, 2026

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2 changes: 1 addition & 1 deletion
src/coreclr/inc/clrconfigvalues.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -433,7 +433,7 @@ RETAIL_CONFIG_STRING_INFO(UNSUPPORTED_ETW_ObjectAllocationEventsPerTypePerSec, W
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapEnabled, W("PerfMapEnabled"), 0, "This flag is used on Linux and macOS to enable writing /tmp/perf-$pid.map. It is disabled by default")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapIgnoreSignal, W("PerfMapIgnoreSignal"), 0, "When perf map is enabled, this option will configure the specified signal to be accepted and ignored as a marker in the perf logs. It is disabled by default")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapShowOptimizationTiers, W("PerfMapShowOptimizationTiers"), 1, "Shows optimization tiers in the perf map for methods, as part of the symbol name. Useful for seeing separate stack frames for different optimization tiers of each method.")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapStubGranularity, W("PerfMapStubGranularity"), 0, "Report stubs with varying amounts of granularity (low bit being zero indicates attempt to group all stubs of a type together) (second lowest bit being non-zero records stubs at individual allocation sites, which is more expensive, but also more accurate).")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapStubGranularity, W("PerfMapStubGranularity"), 0, "Report stubs with varying amounts of granularity (low bit being zero indicates attempt to group all stubs of a type together) (second lowest bit being non-zero records stubs at individual allocation sites, which is more expensive, but also more accurate) (third lowest bit disables stub logging).")
#endif

RETAIL_CONFIG_STRING_INFO(EXTERNAL_StartupDelayMS, W("StartupDelayMS"), "")
Expand Down

6 changes: 5 additions & 1 deletion
src/coreclr/vm/eventing/eventpipe/ds-rt-coreclr.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -233,7 +233,11 @@ static
uint32_t
ds_rt_enable_perfmap (uint32_t type)
{
	LIMITED_METHOD_CONTRACT;
 CONTRACTL
 {
 MODE_PREEMPTIVE;
 }
 CONTRACTL_END;

#ifdef FEATURE_PERFMAP
	PerfMap::PerfMapType perfMapType = (PerfMap::PerfMapType)type;
Expand Down

40 changes: 31 additions & 9 deletions
src/coreclr/vm/perfmap.cpp

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Original file line numberDiff line numberDiff line change
Expand Up@@ -33,6 +33,7 @@ PerfMap * PerfMap::s_Current = nullptr;
bool PerfMap::s_ShowOptimizationTiers = false;
bool PerfMap::s_GroupStubsOfSameType = false;
bool PerfMap::s_IndividualAllocationStubReporting = false;
bool PerfMap::s_LogStubs = false;

unsigned PerfMap::s_StubsMapped = 0;
CrstStatic PerfMap::s_csPerfMap;
Expand All@@ -47,7 +48,15 @@ void PerfMap::Initialize()
{
 LIMITED_METHOD_CONTRACT;

 s_csPerfMap.Init(CrstPerfMap);
 // Use CRST_UNSAFE_ANYMODE to avoid a GC-mode toggle deadlock: callers such as
 // CodeFragmentHeap::RealAllocAlignedMem hold CRST_UNSAFE_ANYMODE locks in cooperative
 // mode. A default Crst here would toggle cooperative->preemptive->acquire->cooperative,
 // and the post-acquire DisablePreemptiveGC can block on a pending GC suspension,
 // forming a deadlock cycle with threads waiting on the outer UNSAFE_ANYMODE lock.
 // All data accessed under this lock is native (FILE*, fd, SString) so holding it
 // in cooperative mode does not introduce new GC-safety issues. Doing I/O
 // in cooperative mode is still less than ideal.
 s_csPerfMap.Init(CrstPerfMap, CrstFlags(CRST_UNSAFE_ANYMODE));

 PerfMapType perfMapType = (PerfMapType)CLRConfig::GetConfigValue(CLRConfig::EXTERNAL_PerfMapEnabled);
 PerfMap::Enable(perfMapType, false);
Expand DownExpand Up@@ -77,11 +86,16 @@ void PerfMap::InitializeConfiguration()
 DWORD granularity = CLRConfig::GetConfigValue(CLRConfig::EXTERNAL_PerfMapStubGranularity);
 s_GroupStubsOfSameType = (granularity & 1) != 1;
 s_IndividualAllocationStubReporting = (granularity & 2) != 0;
 s_LogStubs = (granularity & 4) == 0;
}
Comment thread
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void PerfMap::Enable(PerfMapType type, bool sendExisting)
{
 LIMITED_METHOD_CONTRACT;
 CONTRACTL
 {
 MODE_PREEMPTIVE;
 }
 CONTRACTL_END;

 if (type == PerfMapType::DISABLED)
 {
Expand DownExpand Up@@ -294,8 +308,6 @@ void PerfMap::WriteLine(SString& line)

void PerfMap::LogJITCompiledMethod(MethodDesc * pMethod, PCODE pCode, size_t codeSize, PrepareCodeConfig *pConfig)
{
 LIMITED_METHOD_CONTRACT;

 CONTRACTL{
 THROWS;
 GC_NOTRIGGER;
Expand DownExpand Up@@ -349,7 +361,12 @@ void PerfMap::LogJITCompiledMethod(MethodDesc * pMethod, PCODE pCode, size_t cod
// Log a pre-compiled method to the perfmap.
void PerfMap::LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)
{
 LIMITED_METHOD_CONTRACT;
 CONTRACTL
 {
 THROWS;
 MODE_PREEMPTIVE;
Comment thread
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 }
 CONTRACTL_END;

 if (!s_enabled)
 {
Expand DownExpand Up@@ -385,14 +402,14 @@ void PerfMap::LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)

 if (methodRegionInfo.coldSize > 0)
 {
 CrstHolder ch(&(s_csPerfMap));

 if (s_ShowOptimizationTiers)
 {
 pMethod->GetFullMethodInfo(name);
 name.Append(W("[PreJit-cold]"));
 }

 CrstHolder ch(&(s_csPerfMap));
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 PAL_PerfJitDump_LogMethod((void*)methodRegionInfo.coldStartAddress, methodRegionInfo.coldSize, name.GetUTF8(), nullptr, nullptr, /*reportCodeBlock*/true);
 }
 }
Expand All@@ -402,9 +419,14 @@ void PerfMap::LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)
// Log a set of stub to the map.
void PerfMap::LogStubs(const char* stubType, const char* stubOwner, PCODE pCode, size_t codeSize, PerfMapStubType stubAllocationType)
{
 LIMITED_METHOD_CONTRACT;
 CONTRACTL
 {
 GC_NOTRIGGER;
 MODE_ANY;
 }
 CONTRACTL_END;

 if (!s_enabled)
 if (!s_enabled || !s_LogStubs)
 {
 return;
 }
Expand Down

48 changes: 48 additions & 0 deletions
src/coreclr/vm/perfmap.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -19,6 +19,52 @@ enum class PerfMapStubType
 Individual
};

#ifndef FEATURE_PERFMAP

class PerfMap
{
public:
 static bool IsEnabled()
 {
#ifdef DEBUG
 return true;
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#else
 return false;
#endif
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 }
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 static void LogJITCompiledMethod(MethodDesc * pMethod, PCODE pCode, size_t codeSize, PrepareCodeConfig *pConfig)
 {
 CONTRACTL
 {
 THROWS;
 MODE_PREEMPTIVE;
 }
 CONTRACTL_END;
 }

 static void LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)
 {
 CONTRACTL
 {
 THROWS;
 MODE_PREEMPTIVE;
 }
 CONTRACTL_END;
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 }

 static void LogStubs(const char* stubType, const char* stubOwner, PCODE pCode, size_t codeSize, PerfMapStubType stubAllocationType)
 {
 CONTRACTL
 {
 GC_NOTRIGGER;
 MODE_ANY;
 }
 CONTRACTL_END;
 }
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};

#else // FEATURE_PERFMAP

class PerfMap
{
private:
Expand All@@ -36,6 +82,7 @@ class PerfMap
 // Indicate current stub granularity rules
 static bool s_GroupStubsOfSameType;
 static bool s_IndividualAllocationStubReporting;
 static bool s_LogStubs; // If false, do not log stubs at all

 // Set to true if an error is encountered when writing to the file.
 static unsigned s_StubsMapped;
Expand DownExpand Up@@ -112,4 +159,5 @@ class PerfMap

 static bool LowGranularityStubs() { return !s_IndividualAllocationStubReporting; }
};
#endif // FEATURE_PERFMAP
#endif // PERFPID_H

85 changes: 58 additions & 27 deletions
src/coreclr/vm/virtualcallstub.cpp

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Original file line numberDiff line numberDiff line change
Expand Up@@ -10,9 +10,7 @@
#include "comdelegate.h"
#include <dn-stdio.h>

#ifdef FEATURE_PERFMAP
#include "perfmap.h"
#endif

#ifndef DACCESS_COMPILE

Expand DownExpand Up@@ -1051,7 +1049,19 @@ PCODE VirtualCallStubManager::GetCallStub(DispatchToken token)
 {
 if ((stub = (PCODE)(lookups->Find(&probeL))) == CALL_STUB_EMPTY_ENTRY)
 {
 LookupHolder *pLookupHolder = GenerateLookupStub(addrOfResolver, token.To_SIZE_T());
 LookupHolder *pLookupHolder;
 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
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 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pLookupHolder = GenerateLookupStub(addrOfResolver, token.To_SIZE_T());
 }

 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
 BOOL success = lookups->SetUpProber(token.To_SIZE_T(), 0, &probeL);
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 _ASSERTE(success);
 }
 stub = (PCODE) (lookups->Add((size_t)(pLookupHolder->stub()->entryPoint()), &probeL));
 }
 }
Expand DownExpand Up@@ -1082,7 +1092,20 @@ PCODE VirtualCallStubManager::GetVTableCallStub(DWORD slot)
 {
 if ((stub = (PCODE)(vtableCallers->Find(&probe))) == CALL_STUB_EMPTY_ENTRY)
 {
 VTableCallHolder *pHolder = GenerateVTableCallStub(slot);
 VTableCallHolder *pHolder;

 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pHolder = GenerateVTableCallStub(slot);
 }

 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
 BOOL success = vtableCallers->SetUpProber(DispatchToken::CreateDispatchToken(slot).To_SIZE_T(), 0, &probe);
 _ASSERTE(success);
 }
 stub = (PCODE)(vtableCallers->Add((size_t)(pHolder->stub()->entryPoint()), &probe));
 }
 }
Expand DownExpand Up@@ -1115,9 +1138,7 @@ VTableCallHolder* VirtualCallStubManager::GenerateVTableCallStub(DWORD slot)
 LOG((LF_STUBS, LL_INFO10000, "GenerateVTableCallStub for slot " FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(slot), DBG_ADDR(pHolder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateVTableCallStub", (PCODE)pHolder->stub(), pHolder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN(pHolder);
}
Expand DownExpand Up@@ -2054,14 +2075,24 @@ PCODE VirtualCallStubManager::ResolveWorker(StubCallSite* pCallSite,
 }
#endif // TARGET_X86 && !UNIX_X86_ABI

 pResolveHolder = GenerateResolveStub(pResolverFcn,
 pBackPatchFcn,
 token.To_SIZE_T()
 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pResolveHolder = GenerateResolveStub(pResolverFcn,
 pBackPatchFcn,
 token.To_SIZE_T()
#if defined(TARGET_X86) && !defined(UNIX_X86_ABI)
 , stackArgumentsSize
, stackArgumentsSize
#endif
 );
 }

 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
 BOOL success = resolvers->SetUpProber(token.To_SIZE_T(), 0, &probeR);
 _ASSERTE(success);
 }
 // Add the resolve entrypoint into the cache.
 //@TODO: Can we store a pointer to the holder rather than the entrypoint?
 resolvers->Add((size_t)(pResolveHolder->stub()->resolveEntryPoint()), &probeR);
Expand DownExpand Up@@ -2095,9 +2126,12 @@ PCODE VirtualCallStubManager::ResolveWorker(StubCallSite* pCallSite,
 if (addrOfDispatch == CALL_STUB_EMPTY_ENTRY)
 {
 PCODE addrOfFail = pResolveHolder->stub()->failEntryPoint();
 bool reenteredCooperativeGCMode = false;
 pDispatchHolder = GenerateDispatchStub(
 target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pDispatchHolder = GenerateDispatchStub(
 target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
 }
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 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
Expand DownExpand Up@@ -2208,9 +2242,12 @@ PCODE VirtualCallStubManager::ResolveWorker(StubCallSite* pCallSite,
 // so we may have to create it now
 ResolveHolder* pResolveHolder = ResolveHolder::FromResolveEntry(pCallSite->GetSiteTarget());
 PCODE addrOfFail = pResolveHolder->stub()->failEntryPoint();
 bool reenteredCooperativeGCMode = false;
 pDispatchHolder = GenerateDispatchStub(
 target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pDispatchHolder = GenerateDispatchStub(
 target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
 }
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 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
Expand DownExpand Up@@ -2799,7 +2836,6 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStub(PCODE ad
 PRECONDITION(addrOfFail != NULL);
 PRECONDITION(CheckPointer(pMTExpected));
 PRECONDITION(pMayHaveReenteredCooperativeGCMode != nullptr);
 PRECONDITION(!*pMayHaveReenteredCooperativeGCMode);
 POSTCONDITION(CheckPointer(RETVAL));
 } CONTRACT_END;

Expand DownExpand Up@@ -2862,9 +2898,7 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStub(PCODE ad
 LOG((LF_STUBS, LL_INFO10000, "GenerateDispatchStub for token" FMT_ADDR "and pMT" FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(dispatchToken), DBG_ADDR(pMTExpected), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateDispatchStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN (holder);
}
Expand All@@ -2888,7 +2922,6 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStubLong(PCODE
 PRECONDITION(addrOfFail != NULL);
 PRECONDITION(CheckPointer(pMTExpected));
 PRECONDITION(pMayHaveReenteredCooperativeGCMode != nullptr);
 PRECONDITION(!*pMayHaveReenteredCooperativeGCMode);
 POSTCONDITION(CheckPointer(RETVAL));
 } CONTRACT_END;

Expand DownExpand Up@@ -2923,9 +2956,7 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStubLong(PCODE
 LOG((LF_STUBS, LL_INFO10000, "GenerateDispatchStub for token" FMT_ADDR "and pMT" FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(dispatchToken), DBG_ADDR(pMTExpected), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateDispatchStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN (holder);
}
Expand DownExpand Up@@ -3021,9 +3052,7 @@ ResolveHolder *VirtualCallStubManager::GenerateResolveStub(PCODE addr
 LOG((LF_STUBS, LL_INFO10000, "GenerateResolveStub for token" FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(dispatchToken), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateResolveStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN (holder);
}
Expand DownExpand Up@@ -3054,9 +3083,7 @@ LookupHolder *VirtualCallStubManager::GenerateLookupStub(PCODE addrOfResolver, s
 LOG((LF_STUBS, LL_INFO10000, "GenerateLookupStub for token" FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(dispatchToken), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateLookupStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN (holder);
}
Expand DownExpand Up@@ -3084,8 +3111,12 @@ ResolveCacheElem *VirtualCallStubManager::GenerateResolveCacheElem(void *addrOfC
 CONSISTENCY_CHECK(CheckPointer(pMTExpected));

 //allocate from the requisite heap and set the appropriate fields
 ResolveCacheElem *e = (ResolveCacheElem*) (void*)
 ResolveCacheElem *e;
 {
 GCX_NOTRIGGER();
 e = (ResolveCacheElem*) (void*)
 cache_entry_heap->AllocAlignedMem(sizeof(ResolveCacheElem), CODE_SIZE_ALIGN);
 }

 e->pMT = pMTExpected;
 e->token = token;
Expand Down
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if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {
var url = new URL(ref);
var q = url.searchParams.get('q') || url.searchParams.get('p');
if (q) {
terms = q.split(/\s+/).filter(function(t) { return t.length > 2; });
}
}
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style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';
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Array.from(node.childNodes).forEach(highlight);
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mutations.forEach(function(m) {
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if (node.nodeType === 1 || node.nodeType === 3) highlight(node);
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})();
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try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Change the PerfMap crst into an UNSAFE_ANYMODE crst by davidwrighton · Pull Request #129021 · dotnet/runtime · GitHub
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Change the PerfMap crst into an UNSAFE_ANYMODE crst#129021

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 Merged

davidwrighton
merged 8 commits into

from

Jun 8, 2026
 Merged


Change the PerfMap crst into an UNSAFE_ANYMODE crst
#129021
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4f02657

Add logic to handle some simple cases where moving to preemptive is m…


davidwrighton Jun 4, 2026
4e4a6f6

Code review feedback


davidwrighton Jun 5, 2026
95630a4

Add feature to disable reporting of stubs via PerfMap


davidwrighton Jun 5, 2026
fa3cfe6

Reverse polarity of new flag


davidwrighton Jun 5, 2026
2f6a3cd

And update env flag doc in clrconfigvalues.h


davidwrighton Jun 5, 2026
3e68fd6

Apply suggestions from code review


davidwrighton Jun 8, 2026
2436293

Apply suggestion from @jkotas


jkotas Jun 8, 2026
1a6c35a

Apply suggestions from code review


jkotas Jun 8, 2026

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2 changes: 1 addition & 1 deletion
src/coreclr/inc/clrconfigvalues.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -433,7 +433,7 @@ RETAIL_CONFIG_STRING_INFO(UNSUPPORTED_ETW_ObjectAllocationEventsPerTypePerSec, W
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapEnabled, W("PerfMapEnabled"), 0, "This flag is used on Linux and macOS to enable writing /tmp/perf-$pid.map. It is disabled by default")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapIgnoreSignal, W("PerfMapIgnoreSignal"), 0, "When perf map is enabled, this option will configure the specified signal to be accepted and ignored as a marker in the perf logs. It is disabled by default")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapShowOptimizationTiers, W("PerfMapShowOptimizationTiers"), 1, "Shows optimization tiers in the perf map for methods, as part of the symbol name. Useful for seeing separate stack frames for different optimization tiers of each method.")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapStubGranularity, W("PerfMapStubGranularity"), 0, "Report stubs with varying amounts of granularity (low bit being zero indicates attempt to group all stubs of a type together) (second lowest bit being non-zero records stubs at individual allocation sites, which is more expensive, but also more accurate).")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapStubGranularity, W("PerfMapStubGranularity"), 0, "Report stubs with varying amounts of granularity (low bit being zero indicates attempt to group all stubs of a type together) (second lowest bit being non-zero records stubs at individual allocation sites, which is more expensive, but also more accurate) (third lowest bit disables stub logging).")
#endif

RETAIL_CONFIG_STRING_INFO(EXTERNAL_StartupDelayMS, W("StartupDelayMS"), "")
Expand Down

6 changes: 5 additions & 1 deletion
src/coreclr/vm/eventing/eventpipe/ds-rt-coreclr.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -233,7 +233,11 @@ static
uint32_t
ds_rt_enable_perfmap (uint32_t type)
{
	LIMITED_METHOD_CONTRACT;
 CONTRACTL
 {
 MODE_PREEMPTIVE;
 }
 CONTRACTL_END;

#ifdef FEATURE_PERFMAP
	PerfMap::PerfMapType perfMapType = (PerfMap::PerfMapType)type;
Expand Down

40 changes: 31 additions & 9 deletions
src/coreclr/vm/perfmap.cpp

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Original file line numberDiff line numberDiff line change
Expand Up@@ -33,6 +33,7 @@ PerfMap * PerfMap::s_Current = nullptr;
bool PerfMap::s_ShowOptimizationTiers = false;
bool PerfMap::s_GroupStubsOfSameType = false;
bool PerfMap::s_IndividualAllocationStubReporting = false;
bool PerfMap::s_LogStubs = false;

unsigned PerfMap::s_StubsMapped = 0;
CrstStatic PerfMap::s_csPerfMap;
Expand All@@ -47,7 +48,15 @@ void PerfMap::Initialize()
{
 LIMITED_METHOD_CONTRACT;

 s_csPerfMap.Init(CrstPerfMap);
 // Use CRST_UNSAFE_ANYMODE to avoid a GC-mode toggle deadlock: callers such as
 // CodeFragmentHeap::RealAllocAlignedMem hold CRST_UNSAFE_ANYMODE locks in cooperative
 // mode. A default Crst here would toggle cooperative->preemptive->acquire->cooperative,
 // and the post-acquire DisablePreemptiveGC can block on a pending GC suspension,
 // forming a deadlock cycle with threads waiting on the outer UNSAFE_ANYMODE lock.
 // All data accessed under this lock is native (FILE*, fd, SString) so holding it
 // in cooperative mode does not introduce new GC-safety issues. Doing I/O
 // in cooperative mode is still less than ideal.
 s_csPerfMap.Init(CrstPerfMap, CrstFlags(CRST_UNSAFE_ANYMODE));

 PerfMapType perfMapType = (PerfMapType)CLRConfig::GetConfigValue(CLRConfig::EXTERNAL_PerfMapEnabled);
 PerfMap::Enable(perfMapType, false);
Expand DownExpand Up@@ -77,11 +86,16 @@ void PerfMap::InitializeConfiguration()
 DWORD granularity = CLRConfig::GetConfigValue(CLRConfig::EXTERNAL_PerfMapStubGranularity);
 s_GroupStubsOfSameType = (granularity & 1) != 1;
 s_IndividualAllocationStubReporting = (granularity & 2) != 0;
 s_LogStubs = (granularity & 4) == 0;
}
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void PerfMap::Enable(PerfMapType type, bool sendExisting)
{
 LIMITED_METHOD_CONTRACT;
 CONTRACTL
 {
 MODE_PREEMPTIVE;
 }
 CONTRACTL_END;

 if (type == PerfMapType::DISABLED)
 {
Expand DownExpand Up@@ -294,8 +308,6 @@ void PerfMap::WriteLine(SString& line)

void PerfMap::LogJITCompiledMethod(MethodDesc * pMethod, PCODE pCode, size_t codeSize, PrepareCodeConfig *pConfig)
{
 LIMITED_METHOD_CONTRACT;

 CONTRACTL{
 THROWS;
 GC_NOTRIGGER;
Expand DownExpand Up@@ -349,7 +361,12 @@ void PerfMap::LogJITCompiledMethod(MethodDesc * pMethod, PCODE pCode, size_t cod
// Log a pre-compiled method to the perfmap.
void PerfMap::LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)
{
 LIMITED_METHOD_CONTRACT;
 CONTRACTL
 {
 THROWS;
 MODE_PREEMPTIVE;
Comment thread
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 }
 CONTRACTL_END;

 if (!s_enabled)
 {
Expand DownExpand Up@@ -385,14 +402,14 @@ void PerfMap::LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)

 if (methodRegionInfo.coldSize > 0)
 {
 CrstHolder ch(&(s_csPerfMap));

 if (s_ShowOptimizationTiers)
 {
 pMethod->GetFullMethodInfo(name);
 name.Append(W("[PreJit-cold]"));
 }

 CrstHolder ch(&(s_csPerfMap));
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 PAL_PerfJitDump_LogMethod((void*)methodRegionInfo.coldStartAddress, methodRegionInfo.coldSize, name.GetUTF8(), nullptr, nullptr, /*reportCodeBlock*/true);
 }
 }
Expand All@@ -402,9 +419,14 @@ void PerfMap::LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)
// Log a set of stub to the map.
void PerfMap::LogStubs(const char* stubType, const char* stubOwner, PCODE pCode, size_t codeSize, PerfMapStubType stubAllocationType)
{
 LIMITED_METHOD_CONTRACT;
 CONTRACTL
 {
 GC_NOTRIGGER;
 MODE_ANY;
 }
 CONTRACTL_END;

 if (!s_enabled)
 if (!s_enabled || !s_LogStubs)
 {
 return;
 }
Expand Down

48 changes: 48 additions & 0 deletions
src/coreclr/vm/perfmap.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -19,6 +19,52 @@ enum class PerfMapStubType
 Individual
};

#ifndef FEATURE_PERFMAP

class PerfMap
{
public:
 static bool IsEnabled()
 {
#ifdef DEBUG
 return true;
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#else
 return false;
#endif
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 }
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 static void LogJITCompiledMethod(MethodDesc * pMethod, PCODE pCode, size_t codeSize, PrepareCodeConfig *pConfig)
 {
 CONTRACTL
 {
 THROWS;
 MODE_PREEMPTIVE;
 }
 CONTRACTL_END;
 }

 static void LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)
 {
 CONTRACTL
 {
 THROWS;
 MODE_PREEMPTIVE;
 }
 CONTRACTL_END;
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 }

 static void LogStubs(const char* stubType, const char* stubOwner, PCODE pCode, size_t codeSize, PerfMapStubType stubAllocationType)
 {
 CONTRACTL
 {
 GC_NOTRIGGER;
 MODE_ANY;
 }
 CONTRACTL_END;
 }
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};

#else // FEATURE_PERFMAP

class PerfMap
{
private:
Expand All@@ -36,6 +82,7 @@ class PerfMap
 // Indicate current stub granularity rules
 static bool s_GroupStubsOfSameType;
 static bool s_IndividualAllocationStubReporting;
 static bool s_LogStubs; // If false, do not log stubs at all

 // Set to true if an error is encountered when writing to the file.
 static unsigned s_StubsMapped;
Expand DownExpand Up@@ -112,4 +159,5 @@ class PerfMap

 static bool LowGranularityStubs() { return !s_IndividualAllocationStubReporting; }
};
#endif // FEATURE_PERFMAP
#endif // PERFPID_H

85 changes: 58 additions & 27 deletions
src/coreclr/vm/virtualcallstub.cpp

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Original file line numberDiff line numberDiff line change
Expand Up@@ -10,9 +10,7 @@
#include "comdelegate.h"
#include <dn-stdio.h>

#ifdef FEATURE_PERFMAP
#include "perfmap.h"
#endif

#ifndef DACCESS_COMPILE

Expand DownExpand Up@@ -1051,7 +1049,19 @@ PCODE VirtualCallStubManager::GetCallStub(DispatchToken token)
 {
 if ((stub = (PCODE)(lookups->Find(&probeL))) == CALL_STUB_EMPTY_ENTRY)
 {
 LookupHolder *pLookupHolder = GenerateLookupStub(addrOfResolver, token.To_SIZE_T());
 LookupHolder *pLookupHolder;
 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
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 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pLookupHolder = GenerateLookupStub(addrOfResolver, token.To_SIZE_T());
 }

 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
 BOOL success = lookups->SetUpProber(token.To_SIZE_T(), 0, &probeL);
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 _ASSERTE(success);
 }
 stub = (PCODE) (lookups->Add((size_t)(pLookupHolder->stub()->entryPoint()), &probeL));
 }
 }
Expand DownExpand Up@@ -1082,7 +1092,20 @@ PCODE VirtualCallStubManager::GetVTableCallStub(DWORD slot)
 {
 if ((stub = (PCODE)(vtableCallers->Find(&probe))) == CALL_STUB_EMPTY_ENTRY)
 {
 VTableCallHolder *pHolder = GenerateVTableCallStub(slot);
 VTableCallHolder *pHolder;

 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pHolder = GenerateVTableCallStub(slot);
 }

 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
 BOOL success = vtableCallers->SetUpProber(DispatchToken::CreateDispatchToken(slot).To_SIZE_T(), 0, &probe);
 _ASSERTE(success);
 }
 stub = (PCODE)(vtableCallers->Add((size_t)(pHolder->stub()->entryPoint()), &probe));
 }
 }
Expand DownExpand Up@@ -1115,9 +1138,7 @@ VTableCallHolder* VirtualCallStubManager::GenerateVTableCallStub(DWORD slot)
 LOG((LF_STUBS, LL_INFO10000, "GenerateVTableCallStub for slot " FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(slot), DBG_ADDR(pHolder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateVTableCallStub", (PCODE)pHolder->stub(), pHolder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN(pHolder);
}
Expand DownExpand Up@@ -2054,14 +2075,24 @@ PCODE VirtualCallStubManager::ResolveWorker(StubCallSite* pCallSite,
 }
#endif // TARGET_X86 && !UNIX_X86_ABI

 pResolveHolder = GenerateResolveStub(pResolverFcn,
 pBackPatchFcn,
 token.To_SIZE_T()
 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pResolveHolder = GenerateResolveStub(pResolverFcn,
 pBackPatchFcn,
 token.To_SIZE_T()
#if defined(TARGET_X86) && !defined(UNIX_X86_ABI)
 , stackArgumentsSize
, stackArgumentsSize
#endif
 );
 }

 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
 BOOL success = resolvers->SetUpProber(token.To_SIZE_T(), 0, &probeR);
 _ASSERTE(success);
 }
 // Add the resolve entrypoint into the cache.
 //@TODO: Can we store a pointer to the holder rather than the entrypoint?
 resolvers->Add((size_t)(pResolveHolder->stub()->resolveEntryPoint()), &probeR);
Expand DownExpand Up@@ -2095,9 +2126,12 @@ PCODE VirtualCallStubManager::ResolveWorker(StubCallSite* pCallSite,
 if (addrOfDispatch == CALL_STUB_EMPTY_ENTRY)
 {
 PCODE addrOfFail = pResolveHolder->stub()->failEntryPoint();
 bool reenteredCooperativeGCMode = false;
 pDispatchHolder = GenerateDispatchStub(
 target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pDispatchHolder = GenerateDispatchStub(
 target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
 }
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 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
Expand DownExpand Up@@ -2208,9 +2242,12 @@ PCODE VirtualCallStubManager::ResolveWorker(StubCallSite* pCallSite,
 // so we may have to create it now
 ResolveHolder* pResolveHolder = ResolveHolder::FromResolveEntry(pCallSite->GetSiteTarget());
 PCODE addrOfFail = pResolveHolder->stub()->failEntryPoint();
 bool reenteredCooperativeGCMode = false;
 pDispatchHolder = GenerateDispatchStub(
 target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pDispatchHolder = GenerateDispatchStub(
 target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
 }
Comment thread
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 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
Expand DownExpand Up@@ -2799,7 +2836,6 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStub(PCODE ad
 PRECONDITION(addrOfFail != NULL);
 PRECONDITION(CheckPointer(pMTExpected));
 PRECONDITION(pMayHaveReenteredCooperativeGCMode != nullptr);
 PRECONDITION(!*pMayHaveReenteredCooperativeGCMode);
 POSTCONDITION(CheckPointer(RETVAL));
 } CONTRACT_END;

Expand DownExpand Up@@ -2862,9 +2898,7 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStub(PCODE ad
 LOG((LF_STUBS, LL_INFO10000, "GenerateDispatchStub for token" FMT_ADDR "and pMT" FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(dispatchToken), DBG_ADDR(pMTExpected), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateDispatchStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN (holder);
}
Expand All@@ -2888,7 +2922,6 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStubLong(PCODE
 PRECONDITION(addrOfFail != NULL);
 PRECONDITION(CheckPointer(pMTExpected));
 PRECONDITION(pMayHaveReenteredCooperativeGCMode != nullptr);
 PRECONDITION(!*pMayHaveReenteredCooperativeGCMode);
 POSTCONDITION(CheckPointer(RETVAL));
 } CONTRACT_END;

Expand DownExpand Up@@ -2923,9 +2956,7 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStubLong(PCODE
 LOG((LF_STUBS, LL_INFO10000, "GenerateDispatchStub for token" FMT_ADDR "and pMT" FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(dispatchToken), DBG_ADDR(pMTExpected), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateDispatchStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN (holder);
}
Expand DownExpand Up@@ -3021,9 +3052,7 @@ ResolveHolder *VirtualCallStubManager::GenerateResolveStub(PCODE addr
 LOG((LF_STUBS, LL_INFO10000, "GenerateResolveStub for token" FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(dispatchToken), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateResolveStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN (holder);
}
Expand DownExpand Up@@ -3054,9 +3083,7 @@ LookupHolder *VirtualCallStubManager::GenerateLookupStub(PCODE addrOfResolver, s
 LOG((LF_STUBS, LL_INFO10000, "GenerateLookupStub for token" FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(dispatchToken), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateLookupStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN (holder);
}
Expand DownExpand Up@@ -3084,8 +3111,12 @@ ResolveCacheElem *VirtualCallStubManager::GenerateResolveCacheElem(void *addrOfC
 CONSISTENCY_CHECK(CheckPointer(pMTExpected));

 //allocate from the requisite heap and set the appropriate fields
 ResolveCacheElem *e = (ResolveCacheElem*) (void*)
 ResolveCacheElem *e;
 {
 GCX_NOTRIGGER();
 e = (ResolveCacheElem*) (void*)
 cache_entry_heap->AllocAlignedMem(sizeof(ResolveCacheElem), CODE_SIZE_ALIGN);
 }

 e->pMT = pMTExpected;
 e->token = token;
Expand Down
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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Strip utm_, fbclid, gclid, etc. from all links on page
(function() {
var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',
'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',
'ref', 'ref_src', 'source', 'medium', 'campaign'];
function cleanUrl(url) {
try {
var u = new URL(url, window.location.origin);
var changed = false;
trackingParams.forEach(function(p) {
if (u.searchParams.has(p)) {
u.searchParams.delete(p);
changed = true;
}
});
return changed ? u.toString() : url;
} catch (e) {
return url;
}
}
function cleanLinks() {
document.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
cleanLinks();
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1) {
if (node.tagName === 'A') cleanLinks();
node.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '
Change the PerfMap crst into an UNSAFE_ANYMODE crst by davidwrighton · Pull Request #129021 · dotnet/runtime · GitHub
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 Merged

davidwrighton
merged 8 commits into

from

Jun 8, 2026
 Merged


Change the PerfMap crst into an UNSAFE_ANYMODE crst
#129021
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4f02657

Add logic to handle some simple cases where moving to preemptive is m…


davidwrighton Jun 4, 2026
4e4a6f6

Code review feedback


davidwrighton Jun 5, 2026
95630a4

Add feature to disable reporting of stubs via PerfMap


davidwrighton Jun 5, 2026
fa3cfe6

Reverse polarity of new flag


davidwrighton Jun 5, 2026
2f6a3cd

And update env flag doc in clrconfigvalues.h


davidwrighton Jun 5, 2026
3e68fd6

Apply suggestions from code review


davidwrighton Jun 8, 2026
2436293

Apply suggestion from @jkotas


jkotas Jun 8, 2026
1a6c35a

Apply suggestions from code review


jkotas Jun 8, 2026

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2 changes: 1 addition & 1 deletion
src/coreclr/inc/clrconfigvalues.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -433,7 +433,7 @@ RETAIL_CONFIG_STRING_INFO(UNSUPPORTED_ETW_ObjectAllocationEventsPerTypePerSec, W
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapEnabled, W("PerfMapEnabled"), 0, "This flag is used on Linux and macOS to enable writing /tmp/perf-$pid.map. It is disabled by default")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapIgnoreSignal, W("PerfMapIgnoreSignal"), 0, "When perf map is enabled, this option will configure the specified signal to be accepted and ignored as a marker in the perf logs. It is disabled by default")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapShowOptimizationTiers, W("PerfMapShowOptimizationTiers"), 1, "Shows optimization tiers in the perf map for methods, as part of the symbol name. Useful for seeing separate stack frames for different optimization tiers of each method.")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapStubGranularity, W("PerfMapStubGranularity"), 0, "Report stubs with varying amounts of granularity (low bit being zero indicates attempt to group all stubs of a type together) (second lowest bit being non-zero records stubs at individual allocation sites, which is more expensive, but also more accurate).")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapStubGranularity, W("PerfMapStubGranularity"), 0, "Report stubs with varying amounts of granularity (low bit being zero indicates attempt to group all stubs of a type together) (second lowest bit being non-zero records stubs at individual allocation sites, which is more expensive, but also more accurate) (third lowest bit disables stub logging).")
#endif

RETAIL_CONFIG_STRING_INFO(EXTERNAL_StartupDelayMS, W("StartupDelayMS"), "")
Expand Down

6 changes: 5 additions & 1 deletion
src/coreclr/vm/eventing/eventpipe/ds-rt-coreclr.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -233,7 +233,11 @@ static
uint32_t
ds_rt_enable_perfmap (uint32_t type)
{
	LIMITED_METHOD_CONTRACT;
 CONTRACTL
 {
 MODE_PREEMPTIVE;
 }
 CONTRACTL_END;

#ifdef FEATURE_PERFMAP
	PerfMap::PerfMapType perfMapType = (PerfMap::PerfMapType)type;
Expand Down

40 changes: 31 additions & 9 deletions
src/coreclr/vm/perfmap.cpp

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Original file line numberDiff line numberDiff line change
Expand Up@@ -33,6 +33,7 @@ PerfMap * PerfMap::s_Current = nullptr;
bool PerfMap::s_ShowOptimizationTiers = false;
bool PerfMap::s_GroupStubsOfSameType = false;
bool PerfMap::s_IndividualAllocationStubReporting = false;
bool PerfMap::s_LogStubs = false;

unsigned PerfMap::s_StubsMapped = 0;
CrstStatic PerfMap::s_csPerfMap;
Expand All@@ -47,7 +48,15 @@ void PerfMap::Initialize()
{
 LIMITED_METHOD_CONTRACT;

 s_csPerfMap.Init(CrstPerfMap);
 // Use CRST_UNSAFE_ANYMODE to avoid a GC-mode toggle deadlock: callers such as
 // CodeFragmentHeap::RealAllocAlignedMem hold CRST_UNSAFE_ANYMODE locks in cooperative
 // mode. A default Crst here would toggle cooperative->preemptive->acquire->cooperative,
 // and the post-acquire DisablePreemptiveGC can block on a pending GC suspension,
 // forming a deadlock cycle with threads waiting on the outer UNSAFE_ANYMODE lock.
 // All data accessed under this lock is native (FILE*, fd, SString) so holding it
 // in cooperative mode does not introduce new GC-safety issues. Doing I/O
 // in cooperative mode is still less than ideal.
 s_csPerfMap.Init(CrstPerfMap, CrstFlags(CRST_UNSAFE_ANYMODE));

 PerfMapType perfMapType = (PerfMapType)CLRConfig::GetConfigValue(CLRConfig::EXTERNAL_PerfMapEnabled);
 PerfMap::Enable(perfMapType, false);
Expand DownExpand Up@@ -77,11 +86,16 @@ void PerfMap::InitializeConfiguration()
 DWORD granularity = CLRConfig::GetConfigValue(CLRConfig::EXTERNAL_PerfMapStubGranularity);
 s_GroupStubsOfSameType = (granularity & 1) != 1;
 s_IndividualAllocationStubReporting = (granularity & 2) != 0;
 s_LogStubs = (granularity & 4) == 0;
}
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void PerfMap::Enable(PerfMapType type, bool sendExisting)
{
 LIMITED_METHOD_CONTRACT;
 CONTRACTL
 {
 MODE_PREEMPTIVE;
 }
 CONTRACTL_END;

 if (type == PerfMapType::DISABLED)
 {
Expand DownExpand Up@@ -294,8 +308,6 @@ void PerfMap::WriteLine(SString& line)

void PerfMap::LogJITCompiledMethod(MethodDesc * pMethod, PCODE pCode, size_t codeSize, PrepareCodeConfig *pConfig)
{
 LIMITED_METHOD_CONTRACT;

 CONTRACTL{
 THROWS;
 GC_NOTRIGGER;
Expand DownExpand Up@@ -349,7 +361,12 @@ void PerfMap::LogJITCompiledMethod(MethodDesc * pMethod, PCODE pCode, size_t cod
// Log a pre-compiled method to the perfmap.
void PerfMap::LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)
{
 LIMITED_METHOD_CONTRACT;
 CONTRACTL
 {
 THROWS;
 MODE_PREEMPTIVE;
Comment thread
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 }
 CONTRACTL_END;

 if (!s_enabled)
 {
Expand DownExpand Up@@ -385,14 +402,14 @@ void PerfMap::LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)

 if (methodRegionInfo.coldSize > 0)
 {
 CrstHolder ch(&(s_csPerfMap));

 if (s_ShowOptimizationTiers)
 {
 pMethod->GetFullMethodInfo(name);
 name.Append(W("[PreJit-cold]"));
 }

 CrstHolder ch(&(s_csPerfMap));
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 PAL_PerfJitDump_LogMethod((void*)methodRegionInfo.coldStartAddress, methodRegionInfo.coldSize, name.GetUTF8(), nullptr, nullptr, /*reportCodeBlock*/true);
 }
 }
Expand All@@ -402,9 +419,14 @@ void PerfMap::LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)
// Log a set of stub to the map.
void PerfMap::LogStubs(const char* stubType, const char* stubOwner, PCODE pCode, size_t codeSize, PerfMapStubType stubAllocationType)
{
 LIMITED_METHOD_CONTRACT;
 CONTRACTL
 {
 GC_NOTRIGGER;
 MODE_ANY;
 }
 CONTRACTL_END;

 if (!s_enabled)
 if (!s_enabled || !s_LogStubs)
 {
 return;
 }
Expand Down

48 changes: 48 additions & 0 deletions
src/coreclr/vm/perfmap.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -19,6 +19,52 @@ enum class PerfMapStubType
 Individual
};

#ifndef FEATURE_PERFMAP

class PerfMap
{
public:
 static bool IsEnabled()
 {
#ifdef DEBUG
 return true;
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#else
 return false;
#endif
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 }
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 static void LogJITCompiledMethod(MethodDesc * pMethod, PCODE pCode, size_t codeSize, PrepareCodeConfig *pConfig)
 {
 CONTRACTL
 {
 THROWS;
 MODE_PREEMPTIVE;
 }
 CONTRACTL_END;
 }

 static void LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)
 {
 CONTRACTL
 {
 THROWS;
 MODE_PREEMPTIVE;
 }
 CONTRACTL_END;
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 }

 static void LogStubs(const char* stubType, const char* stubOwner, PCODE pCode, size_t codeSize, PerfMapStubType stubAllocationType)
 {
 CONTRACTL
 {
 GC_NOTRIGGER;
 MODE_ANY;
 }
 CONTRACTL_END;
 }
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};

#else // FEATURE_PERFMAP

class PerfMap
{
private:
Expand All@@ -36,6 +82,7 @@ class PerfMap
 // Indicate current stub granularity rules
 static bool s_GroupStubsOfSameType;
 static bool s_IndividualAllocationStubReporting;
 static bool s_LogStubs; // If false, do not log stubs at all

 // Set to true if an error is encountered when writing to the file.
 static unsigned s_StubsMapped;
Expand DownExpand Up@@ -112,4 +159,5 @@ class PerfMap

 static bool LowGranularityStubs() { return !s_IndividualAllocationStubReporting; }
};
#endif // FEATURE_PERFMAP
#endif // PERFPID_H

85 changes: 58 additions & 27 deletions
src/coreclr/vm/virtualcallstub.cpp

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Original file line numberDiff line numberDiff line change
Expand Up@@ -10,9 +10,7 @@
#include "comdelegate.h"
#include <dn-stdio.h>

#ifdef FEATURE_PERFMAP
#include "perfmap.h"
#endif

#ifndef DACCESS_COMPILE

Expand DownExpand Up@@ -1051,7 +1049,19 @@ PCODE VirtualCallStubManager::GetCallStub(DispatchToken token)
 {
 if ((stub = (PCODE)(lookups->Find(&probeL))) == CALL_STUB_EMPTY_ENTRY)
 {
 LookupHolder *pLookupHolder = GenerateLookupStub(addrOfResolver, token.To_SIZE_T());
 LookupHolder *pLookupHolder;
 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
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 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pLookupHolder = GenerateLookupStub(addrOfResolver, token.To_SIZE_T());
 }

 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
 BOOL success = lookups->SetUpProber(token.To_SIZE_T(), 0, &probeL);
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 _ASSERTE(success);
 }
 stub = (PCODE) (lookups->Add((size_t)(pLookupHolder->stub()->entryPoint()), &probeL));
 }
 }
Expand DownExpand Up@@ -1082,7 +1092,20 @@ PCODE VirtualCallStubManager::GetVTableCallStub(DWORD slot)
 {
 if ((stub = (PCODE)(vtableCallers->Find(&probe))) == CALL_STUB_EMPTY_ENTRY)
 {
 VTableCallHolder *pHolder = GenerateVTableCallStub(slot);
 VTableCallHolder *pHolder;

 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pHolder = GenerateVTableCallStub(slot);
 }

 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
 BOOL success = vtableCallers->SetUpProber(DispatchToken::CreateDispatchToken(slot).To_SIZE_T(), 0, &probe);
 _ASSERTE(success);
 }
 stub = (PCODE)(vtableCallers->Add((size_t)(pHolder->stub()->entryPoint()), &probe));
 }
 }
Expand DownExpand Up@@ -1115,9 +1138,7 @@ VTableCallHolder* VirtualCallStubManager::GenerateVTableCallStub(DWORD slot)
 LOG((LF_STUBS, LL_INFO10000, "GenerateVTableCallStub for slot " FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(slot), DBG_ADDR(pHolder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateVTableCallStub", (PCODE)pHolder->stub(), pHolder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN(pHolder);
}
Expand DownExpand Up@@ -2054,14 +2075,24 @@ PCODE VirtualCallStubManager::ResolveWorker(StubCallSite* pCallSite,
 }
#endif // TARGET_X86 && !UNIX_X86_ABI

 pResolveHolder = GenerateResolveStub(pResolverFcn,
 pBackPatchFcn,
 token.To_SIZE_T()
 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pResolveHolder = GenerateResolveStub(pResolverFcn,
 pBackPatchFcn,
 token.To_SIZE_T()
#if defined(TARGET_X86) && !defined(UNIX_X86_ABI)
 , stackArgumentsSize
, stackArgumentsSize
#endif
 );
 }

 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
 BOOL success = resolvers->SetUpProber(token.To_SIZE_T(), 0, &probeR);
 _ASSERTE(success);
 }
 // Add the resolve entrypoint into the cache.
 //@TODO: Can we store a pointer to the holder rather than the entrypoint?
 resolvers->Add((size_t)(pResolveHolder->stub()->resolveEntryPoint()), &probeR);
Expand DownExpand Up@@ -2095,9 +2126,12 @@ PCODE VirtualCallStubManager::ResolveWorker(StubCallSite* pCallSite,
 if (addrOfDispatch == CALL_STUB_EMPTY_ENTRY)
 {
 PCODE addrOfFail = pResolveHolder->stub()->failEntryPoint();
 bool reenteredCooperativeGCMode = false;
 pDispatchHolder = GenerateDispatchStub(
 target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pDispatchHolder = GenerateDispatchStub(
 target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
 }
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 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
Expand DownExpand Up@@ -2208,9 +2242,12 @@ PCODE VirtualCallStubManager::ResolveWorker(StubCallSite* pCallSite,
 // so we may have to create it now
 ResolveHolder* pResolveHolder = ResolveHolder::FromResolveEntry(pCallSite->GetSiteTarget());
 PCODE addrOfFail = pResolveHolder->stub()->failEntryPoint();
 bool reenteredCooperativeGCMode = false;
 pDispatchHolder = GenerateDispatchStub(
 target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pDispatchHolder = GenerateDispatchStub(
 target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
 }
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 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
Expand DownExpand Up@@ -2799,7 +2836,6 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStub(PCODE ad
 PRECONDITION(addrOfFail != NULL);
 PRECONDITION(CheckPointer(pMTExpected));
 PRECONDITION(pMayHaveReenteredCooperativeGCMode != nullptr);
 PRECONDITION(!*pMayHaveReenteredCooperativeGCMode);
 POSTCONDITION(CheckPointer(RETVAL));
 } CONTRACT_END;

Expand DownExpand Up@@ -2862,9 +2898,7 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStub(PCODE ad
 LOG((LF_STUBS, LL_INFO10000, "GenerateDispatchStub for token" FMT_ADDR "and pMT" FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(dispatchToken), DBG_ADDR(pMTExpected), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateDispatchStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN (holder);
}
Expand All@@ -2888,7 +2922,6 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStubLong(PCODE
 PRECONDITION(addrOfFail != NULL);
 PRECONDITION(CheckPointer(pMTExpected));
 PRECONDITION(pMayHaveReenteredCooperativeGCMode != nullptr);
 PRECONDITION(!*pMayHaveReenteredCooperativeGCMode);
 POSTCONDITION(CheckPointer(RETVAL));
 } CONTRACT_END;

Expand DownExpand Up@@ -2923,9 +2956,7 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStubLong(PCODE
 LOG((LF_STUBS, LL_INFO10000, "GenerateDispatchStub for token" FMT_ADDR "and pMT" FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(dispatchToken), DBG_ADDR(pMTExpected), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateDispatchStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN (holder);
}
Expand DownExpand Up@@ -3021,9 +3052,7 @@ ResolveHolder *VirtualCallStubManager::GenerateResolveStub(PCODE addr
 LOG((LF_STUBS, LL_INFO10000, "GenerateResolveStub for token" FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(dispatchToken), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateResolveStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN (holder);
}
Expand DownExpand Up@@ -3054,9 +3083,7 @@ LookupHolder *VirtualCallStubManager::GenerateLookupStub(PCODE addrOfResolver, s
 LOG((LF_STUBS, LL_INFO10000, "GenerateLookupStub for token" FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(dispatchToken), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateLookupStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN (holder);
}
Expand DownExpand Up@@ -3084,8 +3111,12 @@ ResolveCacheElem *VirtualCallStubManager::GenerateResolveCacheElem(void *addrOfC
 CONSISTENCY_CHECK(CheckPointer(pMTExpected));

 //allocate from the requisite heap and set the appropriate fields
 ResolveCacheElem *e = (ResolveCacheElem*) (void*)
 ResolveCacheElem *e;
 {
 GCX_NOTRIGGER();
 e = (ResolveCacheElem*) (void*)
 cache_entry_heap->AllocAlignedMem(sizeof(ResolveCacheElem), CODE_SIZE_ALIGN);
 }

 e->pMT = pMTExpected;
 e->token = token;
Expand Down
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Change the PerfMap crst into an UNSAFE_ANYMODE crst by davidwrighton · Pull Request #129021 · dotnet/runtime · GitHub
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Jun 8, 2026
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Change the PerfMap crst into an UNSAFE_ANYMODE crst
#129021
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Add logic to handle some simple cases where moving to preemptive is m…


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95630a4

Add feature to disable reporting of stubs via PerfMap


davidwrighton Jun 5, 2026
fa3cfe6

Reverse polarity of new flag


davidwrighton Jun 5, 2026
2f6a3cd

And update env flag doc in clrconfigvalues.h


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3e68fd6

Apply suggestions from code review


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2 changes: 1 addition & 1 deletion
src/coreclr/inc/clrconfigvalues.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -433,7 +433,7 @@ RETAIL_CONFIG_STRING_INFO(UNSUPPORTED_ETW_ObjectAllocationEventsPerTypePerSec, W
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapEnabled, W("PerfMapEnabled"), 0, "This flag is used on Linux and macOS to enable writing /tmp/perf-$pid.map. It is disabled by default")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapIgnoreSignal, W("PerfMapIgnoreSignal"), 0, "When perf map is enabled, this option will configure the specified signal to be accepted and ignored as a marker in the perf logs. It is disabled by default")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapShowOptimizationTiers, W("PerfMapShowOptimizationTiers"), 1, "Shows optimization tiers in the perf map for methods, as part of the symbol name. Useful for seeing separate stack frames for different optimization tiers of each method.")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapStubGranularity, W("PerfMapStubGranularity"), 0, "Report stubs with varying amounts of granularity (low bit being zero indicates attempt to group all stubs of a type together) (second lowest bit being non-zero records stubs at individual allocation sites, which is more expensive, but also more accurate).")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapStubGranularity, W("PerfMapStubGranularity"), 0, "Report stubs with varying amounts of granularity (low bit being zero indicates attempt to group all stubs of a type together) (second lowest bit being non-zero records stubs at individual allocation sites, which is more expensive, but also more accurate) (third lowest bit disables stub logging).")
#endif

RETAIL_CONFIG_STRING_INFO(EXTERNAL_StartupDelayMS, W("StartupDelayMS"), "")
Expand Down

6 changes: 5 additions & 1 deletion
src/coreclr/vm/eventing/eventpipe/ds-rt-coreclr.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -233,7 +233,11 @@ static
uint32_t
ds_rt_enable_perfmap (uint32_t type)
{
	LIMITED_METHOD_CONTRACT;
 CONTRACTL
 {
 MODE_PREEMPTIVE;
 }
 CONTRACTL_END;

#ifdef FEATURE_PERFMAP
	PerfMap::PerfMapType perfMapType = (PerfMap::PerfMapType)type;
Expand Down

40 changes: 31 additions & 9 deletions
src/coreclr/vm/perfmap.cpp

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Original file line numberDiff line numberDiff line change
Expand Up@@ -33,6 +33,7 @@ PerfMap * PerfMap::s_Current = nullptr;
bool PerfMap::s_ShowOptimizationTiers = false;
bool PerfMap::s_GroupStubsOfSameType = false;
bool PerfMap::s_IndividualAllocationStubReporting = false;
bool PerfMap::s_LogStubs = false;

unsigned PerfMap::s_StubsMapped = 0;
CrstStatic PerfMap::s_csPerfMap;
Expand All@@ -47,7 +48,15 @@ void PerfMap::Initialize()
{
 LIMITED_METHOD_CONTRACT;

 s_csPerfMap.Init(CrstPerfMap);
 // Use CRST_UNSAFE_ANYMODE to avoid a GC-mode toggle deadlock: callers such as
 // CodeFragmentHeap::RealAllocAlignedMem hold CRST_UNSAFE_ANYMODE locks in cooperative
 // mode. A default Crst here would toggle cooperative->preemptive->acquire->cooperative,
 // and the post-acquire DisablePreemptiveGC can block on a pending GC suspension,
 // forming a deadlock cycle with threads waiting on the outer UNSAFE_ANYMODE lock.
 // All data accessed under this lock is native (FILE*, fd, SString) so holding it
 // in cooperative mode does not introduce new GC-safety issues. Doing I/O
 // in cooperative mode is still less than ideal.
 s_csPerfMap.Init(CrstPerfMap, CrstFlags(CRST_UNSAFE_ANYMODE));

 PerfMapType perfMapType = (PerfMapType)CLRConfig::GetConfigValue(CLRConfig::EXTERNAL_PerfMapEnabled);
 PerfMap::Enable(perfMapType, false);
Expand DownExpand Up@@ -77,11 +86,16 @@ void PerfMap::InitializeConfiguration()
 DWORD granularity = CLRConfig::GetConfigValue(CLRConfig::EXTERNAL_PerfMapStubGranularity);
 s_GroupStubsOfSameType = (granularity & 1) != 1;
 s_IndividualAllocationStubReporting = (granularity & 2) != 0;
 s_LogStubs = (granularity & 4) == 0;
}
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void PerfMap::Enable(PerfMapType type, bool sendExisting)
{
 LIMITED_METHOD_CONTRACT;
 CONTRACTL
 {
 MODE_PREEMPTIVE;
 }
 CONTRACTL_END;

 if (type == PerfMapType::DISABLED)
 {
Expand DownExpand Up@@ -294,8 +308,6 @@ void PerfMap::WriteLine(SString& line)

void PerfMap::LogJITCompiledMethod(MethodDesc * pMethod, PCODE pCode, size_t codeSize, PrepareCodeConfig *pConfig)
{
 LIMITED_METHOD_CONTRACT;

 CONTRACTL{
 THROWS;
 GC_NOTRIGGER;
Expand DownExpand Up@@ -349,7 +361,12 @@ void PerfMap::LogJITCompiledMethod(MethodDesc * pMethod, PCODE pCode, size_t cod
// Log a pre-compiled method to the perfmap.
void PerfMap::LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)
{
 LIMITED_METHOD_CONTRACT;
 CONTRACTL
 {
 THROWS;
 MODE_PREEMPTIVE;
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 }
 CONTRACTL_END;

 if (!s_enabled)
 {
Expand DownExpand Up@@ -385,14 +402,14 @@ void PerfMap::LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)

 if (methodRegionInfo.coldSize > 0)
 {
 CrstHolder ch(&(s_csPerfMap));

 if (s_ShowOptimizationTiers)
 {
 pMethod->GetFullMethodInfo(name);
 name.Append(W("[PreJit-cold]"));
 }

 CrstHolder ch(&(s_csPerfMap));
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 PAL_PerfJitDump_LogMethod((void*)methodRegionInfo.coldStartAddress, methodRegionInfo.coldSize, name.GetUTF8(), nullptr, nullptr, /*reportCodeBlock*/true);
 }
 }
Expand All@@ -402,9 +419,14 @@ void PerfMap::LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)
// Log a set of stub to the map.
void PerfMap::LogStubs(const char* stubType, const char* stubOwner, PCODE pCode, size_t codeSize, PerfMapStubType stubAllocationType)
{
 LIMITED_METHOD_CONTRACT;
 CONTRACTL
 {
 GC_NOTRIGGER;
 MODE_ANY;
 }
 CONTRACTL_END;

 if (!s_enabled)
 if (!s_enabled || !s_LogStubs)
 {
 return;
 }
Expand Down

48 changes: 48 additions & 0 deletions
src/coreclr/vm/perfmap.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -19,6 +19,52 @@ enum class PerfMapStubType
 Individual
};

#ifndef FEATURE_PERFMAP

class PerfMap
{
public:
 static bool IsEnabled()
 {
#ifdef DEBUG
 return true;
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#else
 return false;
#endif
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 }
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 static void LogJITCompiledMethod(MethodDesc * pMethod, PCODE pCode, size_t codeSize, PrepareCodeConfig *pConfig)
 {
 CONTRACTL
 {
 THROWS;
 MODE_PREEMPTIVE;
 }
 CONTRACTL_END;
 }

 static void LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)
 {
 CONTRACTL
 {
 THROWS;
 MODE_PREEMPTIVE;
 }
 CONTRACTL_END;
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 }

 static void LogStubs(const char* stubType, const char* stubOwner, PCODE pCode, size_t codeSize, PerfMapStubType stubAllocationType)
 {
 CONTRACTL
 {
 GC_NOTRIGGER;
 MODE_ANY;
 }
 CONTRACTL_END;
 }
Comment thread
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};

#else // FEATURE_PERFMAP

class PerfMap
{
private:
Expand All@@ -36,6 +82,7 @@ class PerfMap
 // Indicate current stub granularity rules
 static bool s_GroupStubsOfSameType;
 static bool s_IndividualAllocationStubReporting;
 static bool s_LogStubs; // If false, do not log stubs at all

 // Set to true if an error is encountered when writing to the file.
 static unsigned s_StubsMapped;
Expand DownExpand Up@@ -112,4 +159,5 @@ class PerfMap

 static bool LowGranularityStubs() { return !s_IndividualAllocationStubReporting; }
};
#endif // FEATURE_PERFMAP
#endif // PERFPID_H

85 changes: 58 additions & 27 deletions
src/coreclr/vm/virtualcallstub.cpp

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Original file line numberDiff line numberDiff line change
Expand Up@@ -10,9 +10,7 @@
#include "comdelegate.h"
#include <dn-stdio.h>

#ifdef FEATURE_PERFMAP
#include "perfmap.h"
#endif

#ifndef DACCESS_COMPILE

Expand DownExpand Up@@ -1051,7 +1049,19 @@ PCODE VirtualCallStubManager::GetCallStub(DispatchToken token)
 {
 if ((stub = (PCODE)(lookups->Find(&probeL))) == CALL_STUB_EMPTY_ENTRY)
 {
 LookupHolder *pLookupHolder = GenerateLookupStub(addrOfResolver, token.To_SIZE_T());
 LookupHolder *pLookupHolder;
 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
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 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pLookupHolder = GenerateLookupStub(addrOfResolver, token.To_SIZE_T());
 }

 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
 BOOL success = lookups->SetUpProber(token.To_SIZE_T(), 0, &probeL);
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 _ASSERTE(success);
 }
 stub = (PCODE) (lookups->Add((size_t)(pLookupHolder->stub()->entryPoint()), &probeL));
 }
 }
Expand DownExpand Up@@ -1082,7 +1092,20 @@ PCODE VirtualCallStubManager::GetVTableCallStub(DWORD slot)
 {
 if ((stub = (PCODE)(vtableCallers->Find(&probe))) == CALL_STUB_EMPTY_ENTRY)
 {
 VTableCallHolder *pHolder = GenerateVTableCallStub(slot);
 VTableCallHolder *pHolder;

 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pHolder = GenerateVTableCallStub(slot);
 }

 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
 BOOL success = vtableCallers->SetUpProber(DispatchToken::CreateDispatchToken(slot).To_SIZE_T(), 0, &probe);
 _ASSERTE(success);
 }
 stub = (PCODE)(vtableCallers->Add((size_t)(pHolder->stub()->entryPoint()), &probe));
 }
 }
Expand DownExpand Up@@ -1115,9 +1138,7 @@ VTableCallHolder* VirtualCallStubManager::GenerateVTableCallStub(DWORD slot)
 LOG((LF_STUBS, LL_INFO10000, "GenerateVTableCallStub for slot " FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(slot), DBG_ADDR(pHolder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateVTableCallStub", (PCODE)pHolder->stub(), pHolder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN(pHolder);
}
Expand DownExpand Up@@ -2054,14 +2075,24 @@ PCODE VirtualCallStubManager::ResolveWorker(StubCallSite* pCallSite,
 }
#endif // TARGET_X86 && !UNIX_X86_ABI

 pResolveHolder = GenerateResolveStub(pResolverFcn,
 pBackPatchFcn,
 token.To_SIZE_T()
 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pResolveHolder = GenerateResolveStub(pResolverFcn,
 pBackPatchFcn,
 token.To_SIZE_T()
#if defined(TARGET_X86) && !defined(UNIX_X86_ABI)
 , stackArgumentsSize
, stackArgumentsSize
#endif
 );
 }

 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
 BOOL success = resolvers->SetUpProber(token.To_SIZE_T(), 0, &probeR);
 _ASSERTE(success);
 }
 // Add the resolve entrypoint into the cache.
 //@TODO: Can we store a pointer to the holder rather than the entrypoint?
 resolvers->Add((size_t)(pResolveHolder->stub()->resolveEntryPoint()), &probeR);
Expand DownExpand Up@@ -2095,9 +2126,12 @@ PCODE VirtualCallStubManager::ResolveWorker(StubCallSite* pCallSite,
 if (addrOfDispatch == CALL_STUB_EMPTY_ENTRY)
 {
 PCODE addrOfFail = pResolveHolder->stub()->failEntryPoint();
 bool reenteredCooperativeGCMode = false;
 pDispatchHolder = GenerateDispatchStub(
 target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pDispatchHolder = GenerateDispatchStub(
 target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
 }
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 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
Expand DownExpand Up@@ -2208,9 +2242,12 @@ PCODE VirtualCallStubManager::ResolveWorker(StubCallSite* pCallSite,
 // so we may have to create it now
 ResolveHolder* pResolveHolder = ResolveHolder::FromResolveEntry(pCallSite->GetSiteTarget());
 PCODE addrOfFail = pResolveHolder->stub()->failEntryPoint();
 bool reenteredCooperativeGCMode = false;
 pDispatchHolder = GenerateDispatchStub(
 target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pDispatchHolder = GenerateDispatchStub(
 target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
 }
Comment thread
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 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
Expand DownExpand Up@@ -2799,7 +2836,6 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStub(PCODE ad
 PRECONDITION(addrOfFail != NULL);
 PRECONDITION(CheckPointer(pMTExpected));
 PRECONDITION(pMayHaveReenteredCooperativeGCMode != nullptr);
 PRECONDITION(!*pMayHaveReenteredCooperativeGCMode);
 POSTCONDITION(CheckPointer(RETVAL));
 } CONTRACT_END;

Expand DownExpand Up@@ -2862,9 +2898,7 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStub(PCODE ad
 LOG((LF_STUBS, LL_INFO10000, "GenerateDispatchStub for token" FMT_ADDR "and pMT" FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(dispatchToken), DBG_ADDR(pMTExpected), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateDispatchStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN (holder);
}
Expand All@@ -2888,7 +2922,6 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStubLong(PCODE
 PRECONDITION(addrOfFail != NULL);
 PRECONDITION(CheckPointer(pMTExpected));
 PRECONDITION(pMayHaveReenteredCooperativeGCMode != nullptr);
 PRECONDITION(!*pMayHaveReenteredCooperativeGCMode);
 POSTCONDITION(CheckPointer(RETVAL));
 } CONTRACT_END;

Expand DownExpand Up@@ -2923,9 +2956,7 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStubLong(PCODE
 LOG((LF_STUBS, LL_INFO10000, "GenerateDispatchStub for token" FMT_ADDR "and pMT" FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(dispatchToken), DBG_ADDR(pMTExpected), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateDispatchStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN (holder);
}
Expand DownExpand Up@@ -3021,9 +3052,7 @@ ResolveHolder *VirtualCallStubManager::GenerateResolveStub(PCODE addr
 LOG((LF_STUBS, LL_INFO10000, "GenerateResolveStub for token" FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(dispatchToken), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateResolveStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN (holder);
}
Expand DownExpand Up@@ -3054,9 +3083,7 @@ LookupHolder *VirtualCallStubManager::GenerateLookupStub(PCODE addrOfResolver, s
 LOG((LF_STUBS, LL_INFO10000, "GenerateLookupStub for token" FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(dispatchToken), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateLookupStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN (holder);
}
Expand DownExpand Up@@ -3084,8 +3111,12 @@ ResolveCacheElem *VirtualCallStubManager::GenerateResolveCacheElem(void *addrOfC
 CONSISTENCY_CHECK(CheckPointer(pMTExpected));

 //allocate from the requisite heap and set the appropriate fields
 ResolveCacheElem *e = (ResolveCacheElem*) (void*)
 ResolveCacheElem *e;
 {
 GCX_NOTRIGGER();
 e = (ResolveCacheElem*) (void*)
 cache_entry_heap->AllocAlignedMem(sizeof(ResolveCacheElem), CODE_SIZE_ALIGN);
 }

 e->pMT = pMTExpected;
 e->token = token;
Expand Down
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Change the PerfMap crst into an UNSAFE_ANYMODE crst by davidwrighton · Pull Request #129021 · dotnet/runtime · GitHub
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Change the PerfMap crst into an UNSAFE_ANYMODE crst#129021

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 Merged

davidwrighton
merged 8 commits into

from

Jun 8, 2026
 Merged


Change the PerfMap crst into an UNSAFE_ANYMODE crst
#129021
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4f02657

Add logic to handle some simple cases where moving to preemptive is m…


davidwrighton Jun 4, 2026
4e4a6f6

Code review feedback


davidwrighton Jun 5, 2026
95630a4

Add feature to disable reporting of stubs via PerfMap


davidwrighton Jun 5, 2026
fa3cfe6

Reverse polarity of new flag


davidwrighton Jun 5, 2026
2f6a3cd

And update env flag doc in clrconfigvalues.h


davidwrighton Jun 5, 2026
3e68fd6

Apply suggestions from code review


davidwrighton Jun 8, 2026
2436293

Apply suggestion from @jkotas


jkotas Jun 8, 2026
1a6c35a

Apply suggestions from code review


jkotas Jun 8, 2026

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2 changes: 1 addition & 1 deletion
src/coreclr/inc/clrconfigvalues.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -433,7 +433,7 @@ RETAIL_CONFIG_STRING_INFO(UNSUPPORTED_ETW_ObjectAllocationEventsPerTypePerSec, W
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapEnabled, W("PerfMapEnabled"), 0, "This flag is used on Linux and macOS to enable writing /tmp/perf-$pid.map. It is disabled by default")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapIgnoreSignal, W("PerfMapIgnoreSignal"), 0, "When perf map is enabled, this option will configure the specified signal to be accepted and ignored as a marker in the perf logs. It is disabled by default")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapShowOptimizationTiers, W("PerfMapShowOptimizationTiers"), 1, "Shows optimization tiers in the perf map for methods, as part of the symbol name. Useful for seeing separate stack frames for different optimization tiers of each method.")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapStubGranularity, W("PerfMapStubGranularity"), 0, "Report stubs with varying amounts of granularity (low bit being zero indicates attempt to group all stubs of a type together) (second lowest bit being non-zero records stubs at individual allocation sites, which is more expensive, but also more accurate).")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapStubGranularity, W("PerfMapStubGranularity"), 0, "Report stubs with varying amounts of granularity (low bit being zero indicates attempt to group all stubs of a type together) (second lowest bit being non-zero records stubs at individual allocation sites, which is more expensive, but also more accurate) (third lowest bit disables stub logging).")
#endif

RETAIL_CONFIG_STRING_INFO(EXTERNAL_StartupDelayMS, W("StartupDelayMS"), "")
Expand Down

6 changes: 5 additions & 1 deletion
src/coreclr/vm/eventing/eventpipe/ds-rt-coreclr.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -233,7 +233,11 @@ static
uint32_t
ds_rt_enable_perfmap (uint32_t type)
{
	LIMITED_METHOD_CONTRACT;
 CONTRACTL
 {
 MODE_PREEMPTIVE;
 }
 CONTRACTL_END;

#ifdef FEATURE_PERFMAP
	PerfMap::PerfMapType perfMapType = (PerfMap::PerfMapType)type;
Expand Down

40 changes: 31 additions & 9 deletions
src/coreclr/vm/perfmap.cpp

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Original file line numberDiff line numberDiff line change
Expand Up@@ -33,6 +33,7 @@ PerfMap * PerfMap::s_Current = nullptr;
bool PerfMap::s_ShowOptimizationTiers = false;
bool PerfMap::s_GroupStubsOfSameType = false;
bool PerfMap::s_IndividualAllocationStubReporting = false;
bool PerfMap::s_LogStubs = false;

unsigned PerfMap::s_StubsMapped = 0;
CrstStatic PerfMap::s_csPerfMap;
Expand All@@ -47,7 +48,15 @@ void PerfMap::Initialize()
{
 LIMITED_METHOD_CONTRACT;

 s_csPerfMap.Init(CrstPerfMap);
 // Use CRST_UNSAFE_ANYMODE to avoid a GC-mode toggle deadlock: callers such as
 // CodeFragmentHeap::RealAllocAlignedMem hold CRST_UNSAFE_ANYMODE locks in cooperative
 // mode. A default Crst here would toggle cooperative->preemptive->acquire->cooperative,
 // and the post-acquire DisablePreemptiveGC can block on a pending GC suspension,
 // forming a deadlock cycle with threads waiting on the outer UNSAFE_ANYMODE lock.
 // All data accessed under this lock is native (FILE*, fd, SString) so holding it
 // in cooperative mode does not introduce new GC-safety issues. Doing I/O
 // in cooperative mode is still less than ideal.
 s_csPerfMap.Init(CrstPerfMap, CrstFlags(CRST_UNSAFE_ANYMODE));

 PerfMapType perfMapType = (PerfMapType)CLRConfig::GetConfigValue(CLRConfig::EXTERNAL_PerfMapEnabled);
 PerfMap::Enable(perfMapType, false);
Expand DownExpand Up@@ -77,11 +86,16 @@ void PerfMap::InitializeConfiguration()
 DWORD granularity = CLRConfig::GetConfigValue(CLRConfig::EXTERNAL_PerfMapStubGranularity);
 s_GroupStubsOfSameType = (granularity & 1) != 1;
 s_IndividualAllocationStubReporting = (granularity & 2) != 0;
 s_LogStubs = (granularity & 4) == 0;
}
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void PerfMap::Enable(PerfMapType type, bool sendExisting)
{
 LIMITED_METHOD_CONTRACT;
 CONTRACTL
 {
 MODE_PREEMPTIVE;
 }
 CONTRACTL_END;

 if (type == PerfMapType::DISABLED)
 {
Expand DownExpand Up@@ -294,8 +308,6 @@ void PerfMap::WriteLine(SString& line)

void PerfMap::LogJITCompiledMethod(MethodDesc * pMethod, PCODE pCode, size_t codeSize, PrepareCodeConfig *pConfig)
{
 LIMITED_METHOD_CONTRACT;

 CONTRACTL{
 THROWS;
 GC_NOTRIGGER;
Expand DownExpand Up@@ -349,7 +361,12 @@ void PerfMap::LogJITCompiledMethod(MethodDesc * pMethod, PCODE pCode, size_t cod
// Log a pre-compiled method to the perfmap.
void PerfMap::LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)
{
 LIMITED_METHOD_CONTRACT;
 CONTRACTL
 {
 THROWS;
 MODE_PREEMPTIVE;
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 }
 CONTRACTL_END;

 if (!s_enabled)
 {
Expand DownExpand Up@@ -385,14 +402,14 @@ void PerfMap::LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)

 if (methodRegionInfo.coldSize > 0)
 {
 CrstHolder ch(&(s_csPerfMap));

 if (s_ShowOptimizationTiers)
 {
 pMethod->GetFullMethodInfo(name);
 name.Append(W("[PreJit-cold]"));
 }

 CrstHolder ch(&(s_csPerfMap));
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 PAL_PerfJitDump_LogMethod((void*)methodRegionInfo.coldStartAddress, methodRegionInfo.coldSize, name.GetUTF8(), nullptr, nullptr, /*reportCodeBlock*/true);
 }
 }
Expand All@@ -402,9 +419,14 @@ void PerfMap::LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)
// Log a set of stub to the map.
void PerfMap::LogStubs(const char* stubType, const char* stubOwner, PCODE pCode, size_t codeSize, PerfMapStubType stubAllocationType)
{
 LIMITED_METHOD_CONTRACT;
 CONTRACTL
 {
 GC_NOTRIGGER;
 MODE_ANY;
 }
 CONTRACTL_END;

 if (!s_enabled)
 if (!s_enabled || !s_LogStubs)
 {
 return;
 }
Expand Down

48 changes: 48 additions & 0 deletions
src/coreclr/vm/perfmap.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -19,6 +19,52 @@ enum class PerfMapStubType
 Individual
};

#ifndef FEATURE_PERFMAP

class PerfMap
{
public:
 static bool IsEnabled()
 {
#ifdef DEBUG
 return true;
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#else
 return false;
#endif
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 }
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 static void LogJITCompiledMethod(MethodDesc * pMethod, PCODE pCode, size_t codeSize, PrepareCodeConfig *pConfig)
 {
 CONTRACTL
 {
 THROWS;
 MODE_PREEMPTIVE;
 }
 CONTRACTL_END;
 }

 static void LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)
 {
 CONTRACTL
 {
 THROWS;
 MODE_PREEMPTIVE;
 }
 CONTRACTL_END;
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 }

 static void LogStubs(const char* stubType, const char* stubOwner, PCODE pCode, size_t codeSize, PerfMapStubType stubAllocationType)
 {
 CONTRACTL
 {
 GC_NOTRIGGER;
 MODE_ANY;
 }
 CONTRACTL_END;
 }
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};

#else // FEATURE_PERFMAP

class PerfMap
{
private:
Expand All@@ -36,6 +82,7 @@ class PerfMap
 // Indicate current stub granularity rules
 static bool s_GroupStubsOfSameType;
 static bool s_IndividualAllocationStubReporting;
 static bool s_LogStubs; // If false, do not log stubs at all

 // Set to true if an error is encountered when writing to the file.
 static unsigned s_StubsMapped;
Expand DownExpand Up@@ -112,4 +159,5 @@ class PerfMap

 static bool LowGranularityStubs() { return !s_IndividualAllocationStubReporting; }
};
#endif // FEATURE_PERFMAP
#endif // PERFPID_H

85 changes: 58 additions & 27 deletions
src/coreclr/vm/virtualcallstub.cpp

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Original file line numberDiff line numberDiff line change
Expand Up@@ -10,9 +10,7 @@
#include "comdelegate.h"
#include <dn-stdio.h>

#ifdef FEATURE_PERFMAP
#include "perfmap.h"
#endif

#ifndef DACCESS_COMPILE

Expand DownExpand Up@@ -1051,7 +1049,19 @@ PCODE VirtualCallStubManager::GetCallStub(DispatchToken token)
 {
 if ((stub = (PCODE)(lookups->Find(&probeL))) == CALL_STUB_EMPTY_ENTRY)
 {
 LookupHolder *pLookupHolder = GenerateLookupStub(addrOfResolver, token.To_SIZE_T());
 LookupHolder *pLookupHolder;
 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
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 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pLookupHolder = GenerateLookupStub(addrOfResolver, token.To_SIZE_T());
 }

 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
 BOOL success = lookups->SetUpProber(token.To_SIZE_T(), 0, &probeL);
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 _ASSERTE(success);
 }
 stub = (PCODE) (lookups->Add((size_t)(pLookupHolder->stub()->entryPoint()), &probeL));
 }
 }
Expand DownExpand Up@@ -1082,7 +1092,20 @@ PCODE VirtualCallStubManager::GetVTableCallStub(DWORD slot)
 {
 if ((stub = (PCODE)(vtableCallers->Find(&probe))) == CALL_STUB_EMPTY_ENTRY)
 {
 VTableCallHolder *pHolder = GenerateVTableCallStub(slot);
 VTableCallHolder *pHolder;

 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pHolder = GenerateVTableCallStub(slot);
 }

 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
 BOOL success = vtableCallers->SetUpProber(DispatchToken::CreateDispatchToken(slot).To_SIZE_T(), 0, &probe);
 _ASSERTE(success);
 }
 stub = (PCODE)(vtableCallers->Add((size_t)(pHolder->stub()->entryPoint()), &probe));
 }
 }
Expand DownExpand Up@@ -1115,9 +1138,7 @@ VTableCallHolder* VirtualCallStubManager::GenerateVTableCallStub(DWORD slot)
 LOG((LF_STUBS, LL_INFO10000, "GenerateVTableCallStub for slot " FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(slot), DBG_ADDR(pHolder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateVTableCallStub", (PCODE)pHolder->stub(), pHolder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN(pHolder);
}
Expand DownExpand Up@@ -2054,14 +2075,24 @@ PCODE VirtualCallStubManager::ResolveWorker(StubCallSite* pCallSite,
 }
#endif // TARGET_X86 && !UNIX_X86_ABI

 pResolveHolder = GenerateResolveStub(pResolverFcn,
 pBackPatchFcn,
 token.To_SIZE_T()
 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pResolveHolder = GenerateResolveStub(pResolverFcn,
 pBackPatchFcn,
 token.To_SIZE_T()
#if defined(TARGET_X86) && !defined(UNIX_X86_ABI)
 , stackArgumentsSize
, stackArgumentsSize
#endif
 );
 }

 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
 BOOL success = resolvers->SetUpProber(token.To_SIZE_T(), 0, &probeR);
 _ASSERTE(success);
 }
 // Add the resolve entrypoint into the cache.
 //@TODO: Can we store a pointer to the holder rather than the entrypoint?
 resolvers->Add((size_t)(pResolveHolder->stub()->resolveEntryPoint()), &probeR);
Expand DownExpand Up@@ -2095,9 +2126,12 @@ PCODE VirtualCallStubManager::ResolveWorker(StubCallSite* pCallSite,
 if (addrOfDispatch == CALL_STUB_EMPTY_ENTRY)
 {
 PCODE addrOfFail = pResolveHolder->stub()->failEntryPoint();
 bool reenteredCooperativeGCMode = false;
 pDispatchHolder = GenerateDispatchStub(
 target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pDispatchHolder = GenerateDispatchStub(
 target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
 }
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 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
Expand DownExpand Up@@ -2208,9 +2242,12 @@ PCODE VirtualCallStubManager::ResolveWorker(StubCallSite* pCallSite,
 // so we may have to create it now
 ResolveHolder* pResolveHolder = ResolveHolder::FromResolveEntry(pCallSite->GetSiteTarget());
 PCODE addrOfFail = pResolveHolder->stub()->failEntryPoint();
 bool reenteredCooperativeGCMode = false;
 pDispatchHolder = GenerateDispatchStub(
 target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pDispatchHolder = GenerateDispatchStub(
 target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
 }
Comment thread
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 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
Expand DownExpand Up@@ -2799,7 +2836,6 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStub(PCODE ad
 PRECONDITION(addrOfFail != NULL);
 PRECONDITION(CheckPointer(pMTExpected));
 PRECONDITION(pMayHaveReenteredCooperativeGCMode != nullptr);
 PRECONDITION(!*pMayHaveReenteredCooperativeGCMode);
 POSTCONDITION(CheckPointer(RETVAL));
 } CONTRACT_END;

Expand DownExpand Up@@ -2862,9 +2898,7 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStub(PCODE ad
 LOG((LF_STUBS, LL_INFO10000, "GenerateDispatchStub for token" FMT_ADDR "and pMT" FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(dispatchToken), DBG_ADDR(pMTExpected), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateDispatchStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN (holder);
}
Expand All@@ -2888,7 +2922,6 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStubLong(PCODE
 PRECONDITION(addrOfFail != NULL);
 PRECONDITION(CheckPointer(pMTExpected));
 PRECONDITION(pMayHaveReenteredCooperativeGCMode != nullptr);
 PRECONDITION(!*pMayHaveReenteredCooperativeGCMode);
 POSTCONDITION(CheckPointer(RETVAL));
 } CONTRACT_END;

Expand DownExpand Up@@ -2923,9 +2956,7 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStubLong(PCODE
 LOG((LF_STUBS, LL_INFO10000, "GenerateDispatchStub for token" FMT_ADDR "and pMT" FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(dispatchToken), DBG_ADDR(pMTExpected), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateDispatchStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN (holder);
}
Expand DownExpand Up@@ -3021,9 +3052,7 @@ ResolveHolder *VirtualCallStubManager::GenerateResolveStub(PCODE addr
 LOG((LF_STUBS, LL_INFO10000, "GenerateResolveStub for token" FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(dispatchToken), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateResolveStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN (holder);
}
Expand DownExpand Up@@ -3054,9 +3083,7 @@ LookupHolder *VirtualCallStubManager::GenerateLookupStub(PCODE addrOfResolver, s
 LOG((LF_STUBS, LL_INFO10000, "GenerateLookupStub for token" FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(dispatchToken), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateLookupStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN (holder);
}
Expand DownExpand Up@@ -3084,8 +3111,12 @@ ResolveCacheElem *VirtualCallStubManager::GenerateResolveCacheElem(void *addrOfC
 CONSISTENCY_CHECK(CheckPointer(pMTExpected));

 //allocate from the requisite heap and set the appropriate fields
 ResolveCacheElem *e = (ResolveCacheElem*) (void*)
 ResolveCacheElem *e;
 {
 GCX_NOTRIGGER();
 e = (ResolveCacheElem*) (void*)
 cache_entry_heap->AllocAlignedMem(sizeof(ResolveCacheElem), CODE_SIZE_ALIGN);
 }

 e->pMT = pMTExpected;
 e->token = token;
Expand Down
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if (__m === '*' || __re.test(location.href)) {
// Universal Dark Mode - works on any site
(function() {
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function applyDarkMode() {
if (!enabled) return;
// Create style element if it doesn't exist
var style = document.getElementById('universal-dark-mode-style');
if (!style) {
style = document.createElement('style');
style.id = 'universal-dark-mode-style';
document.head.appendChild(style);
}
// Dark mode CSS - inverts colors but preserves images/video
style.textContent = '
/* Invert everything except media */
html {
filter: invert(1) hue-rotate(180deg) !important;
background: #1a1a2e !important;
}
/* Restore images, videos, iframes, canvas */
img, video, iframe, canvas, svg, picture, [style*="background-image"] {
filter: invert(1) hue-rotate(180deg) !important;
}
/* Preserve specific elements that should not be inverted */
.no-dark-mode, .no-dark-mode *,
[data-theme="light"], [data-theme="light"],
.ace_editor, .ace_editor *,
.CodeMirror, .CodeMirror *,
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.highlight, .highlight *,
pre code, pre code * {
filter: none !important;
}
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filter: invert(1) hue-rotate(180deg) !important;
background: #2d2d44 !important;
border-color: #444 !important;
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::-webkit-scrollbar { background: #1a1a2e !important; }
::-webkit-scrollbar-thumb { background: #444 !important; }
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/* Selection */
::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
';
}
function removeDarkMode() {
var style = document.getElementById('universal-dark-mode-style');
if (style) style.remove();
}
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document.addEventListener('keydown', function(e) {
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enabled = !enabled;
if (enabled) {
applyDarkMode();
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} else {
removeDarkMode();
console.log('[Universal Dark Mode] Disabled');
}
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});
// Apply on load
applyDarkMode();
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var observer = new MutationObserver(function(mutations) {
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applyDarkMode();
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Change the PerfMap crst into an UNSAFE_ANYMODE crst by davidwrighton · Pull Request #129021 · dotnet/runtime · GitHub
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Change the PerfMap crst into an UNSAFE_ANYMODE crst#129021

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 Merged

davidwrighton
merged 8 commits into

from

Jun 8, 2026
 Merged


Change the PerfMap crst into an UNSAFE_ANYMODE crst
#129021
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4f02657

Add logic to handle some simple cases where moving to preemptive is m…


davidwrighton Jun 4, 2026
4e4a6f6

Code review feedback


davidwrighton Jun 5, 2026
95630a4

Add feature to disable reporting of stubs via PerfMap


davidwrighton Jun 5, 2026
fa3cfe6

Reverse polarity of new flag


davidwrighton Jun 5, 2026
2f6a3cd

And update env flag doc in clrconfigvalues.h


davidwrighton Jun 5, 2026
3e68fd6

Apply suggestions from code review


davidwrighton Jun 8, 2026
2436293

Apply suggestion from @jkotas


jkotas Jun 8, 2026
1a6c35a

Apply suggestions from code review


jkotas Jun 8, 2026

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2 changes: 1 addition & 1 deletion
src/coreclr/inc/clrconfigvalues.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -433,7 +433,7 @@ RETAIL_CONFIG_STRING_INFO(UNSUPPORTED_ETW_ObjectAllocationEventsPerTypePerSec, W
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapEnabled, W("PerfMapEnabled"), 0, "This flag is used on Linux and macOS to enable writing /tmp/perf-$pid.map. It is disabled by default")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapIgnoreSignal, W("PerfMapIgnoreSignal"), 0, "When perf map is enabled, this option will configure the specified signal to be accepted and ignored as a marker in the perf logs. It is disabled by default")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapShowOptimizationTiers, W("PerfMapShowOptimizationTiers"), 1, "Shows optimization tiers in the perf map for methods, as part of the symbol name. Useful for seeing separate stack frames for different optimization tiers of each method.")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapStubGranularity, W("PerfMapStubGranularity"), 0, "Report stubs with varying amounts of granularity (low bit being zero indicates attempt to group all stubs of a type together) (second lowest bit being non-zero records stubs at individual allocation sites, which is more expensive, but also more accurate).")
RETAIL_CONFIG_DWORD_INFO(EXTERNAL_PerfMapStubGranularity, W("PerfMapStubGranularity"), 0, "Report stubs with varying amounts of granularity (low bit being zero indicates attempt to group all stubs of a type together) (second lowest bit being non-zero records stubs at individual allocation sites, which is more expensive, but also more accurate) (third lowest bit disables stub logging).")
#endif

RETAIL_CONFIG_STRING_INFO(EXTERNAL_StartupDelayMS, W("StartupDelayMS"), "")
Expand Down

6 changes: 5 additions & 1 deletion
src/coreclr/vm/eventing/eventpipe/ds-rt-coreclr.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -233,7 +233,11 @@ static
uint32_t
ds_rt_enable_perfmap (uint32_t type)
{
	LIMITED_METHOD_CONTRACT;
 CONTRACTL
 {
 MODE_PREEMPTIVE;
 }
 CONTRACTL_END;

#ifdef FEATURE_PERFMAP
	PerfMap::PerfMapType perfMapType = (PerfMap::PerfMapType)type;
Expand Down

40 changes: 31 additions & 9 deletions
src/coreclr/vm/perfmap.cpp

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Original file line numberDiff line numberDiff line change
Expand Up@@ -33,6 +33,7 @@ PerfMap * PerfMap::s_Current = nullptr;
bool PerfMap::s_ShowOptimizationTiers = false;
bool PerfMap::s_GroupStubsOfSameType = false;
bool PerfMap::s_IndividualAllocationStubReporting = false;
bool PerfMap::s_LogStubs = false;

unsigned PerfMap::s_StubsMapped = 0;
CrstStatic PerfMap::s_csPerfMap;
Expand All@@ -47,7 +48,15 @@ void PerfMap::Initialize()
{
 LIMITED_METHOD_CONTRACT;

 s_csPerfMap.Init(CrstPerfMap);
 // Use CRST_UNSAFE_ANYMODE to avoid a GC-mode toggle deadlock: callers such as
 // CodeFragmentHeap::RealAllocAlignedMem hold CRST_UNSAFE_ANYMODE locks in cooperative
 // mode. A default Crst here would toggle cooperative->preemptive->acquire->cooperative,
 // and the post-acquire DisablePreemptiveGC can block on a pending GC suspension,
 // forming a deadlock cycle with threads waiting on the outer UNSAFE_ANYMODE lock.
 // All data accessed under this lock is native (FILE*, fd, SString) so holding it
 // in cooperative mode does not introduce new GC-safety issues. Doing I/O
 // in cooperative mode is still less than ideal.
 s_csPerfMap.Init(CrstPerfMap, CrstFlags(CRST_UNSAFE_ANYMODE));

 PerfMapType perfMapType = (PerfMapType)CLRConfig::GetConfigValue(CLRConfig::EXTERNAL_PerfMapEnabled);
 PerfMap::Enable(perfMapType, false);
Expand DownExpand Up@@ -77,11 +86,16 @@ void PerfMap::InitializeConfiguration()
 DWORD granularity = CLRConfig::GetConfigValue(CLRConfig::EXTERNAL_PerfMapStubGranularity);
 s_GroupStubsOfSameType = (granularity & 1) != 1;
 s_IndividualAllocationStubReporting = (granularity & 2) != 0;
 s_LogStubs = (granularity & 4) == 0;
}
Comment thread
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void PerfMap::Enable(PerfMapType type, bool sendExisting)
{
 LIMITED_METHOD_CONTRACT;
 CONTRACTL
 {
 MODE_PREEMPTIVE;
 }
 CONTRACTL_END;

 if (type == PerfMapType::DISABLED)
 {
Expand DownExpand Up@@ -294,8 +308,6 @@ void PerfMap::WriteLine(SString& line)

void PerfMap::LogJITCompiledMethod(MethodDesc * pMethod, PCODE pCode, size_t codeSize, PrepareCodeConfig *pConfig)
{
 LIMITED_METHOD_CONTRACT;

 CONTRACTL{
 THROWS;
 GC_NOTRIGGER;
Expand DownExpand Up@@ -349,7 +361,12 @@ void PerfMap::LogJITCompiledMethod(MethodDesc * pMethod, PCODE pCode, size_t cod
// Log a pre-compiled method to the perfmap.
void PerfMap::LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)
{
 LIMITED_METHOD_CONTRACT;
 CONTRACTL
 {
 THROWS;
 MODE_PREEMPTIVE;
Comment thread
davidwrighton marked this conversation as resolved.

 }
 CONTRACTL_END;

 if (!s_enabled)
 {
Expand DownExpand Up@@ -385,14 +402,14 @@ void PerfMap::LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)

 if (methodRegionInfo.coldSize > 0)
 {
 CrstHolder ch(&(s_csPerfMap));

 if (s_ShowOptimizationTiers)
 {
 pMethod->GetFullMethodInfo(name);
 name.Append(W("[PreJit-cold]"));
 }

 CrstHolder ch(&(s_csPerfMap));
Comment thread
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 PAL_PerfJitDump_LogMethod((void*)methodRegionInfo.coldStartAddress, methodRegionInfo.coldSize, name.GetUTF8(), nullptr, nullptr, /*reportCodeBlock*/true);
 }
 }
Expand All@@ -402,9 +419,14 @@ void PerfMap::LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)
// Log a set of stub to the map.
void PerfMap::LogStubs(const char* stubType, const char* stubOwner, PCODE pCode, size_t codeSize, PerfMapStubType stubAllocationType)
{
 LIMITED_METHOD_CONTRACT;
 CONTRACTL
 {
 GC_NOTRIGGER;
 MODE_ANY;
 }
 CONTRACTL_END;

 if (!s_enabled)
 if (!s_enabled || !s_LogStubs)
 {
 return;
 }
Expand Down

48 changes: 48 additions & 0 deletions
src/coreclr/vm/perfmap.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -19,6 +19,52 @@ enum class PerfMapStubType
 Individual
};

#ifndef FEATURE_PERFMAP

class PerfMap
{
public:
 static bool IsEnabled()
 {
#ifdef DEBUG
 return true;
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#else
 return false;
#endif
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 }
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 static void LogJITCompiledMethod(MethodDesc * pMethod, PCODE pCode, size_t codeSize, PrepareCodeConfig *pConfig)
 {
 CONTRACTL
 {
 THROWS;
 MODE_PREEMPTIVE;
 }
 CONTRACTL_END;
 }

 static void LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)
 {
 CONTRACTL
 {
 THROWS;
 MODE_PREEMPTIVE;
 }
 CONTRACTL_END;
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 }

 static void LogStubs(const char* stubType, const char* stubOwner, PCODE pCode, size_t codeSize, PerfMapStubType stubAllocationType)
 {
 CONTRACTL
 {
 GC_NOTRIGGER;
 MODE_ANY;
 }
 CONTRACTL_END;
 }
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};

#else // FEATURE_PERFMAP

class PerfMap
{
private:
Expand All@@ -36,6 +82,7 @@ class PerfMap
 // Indicate current stub granularity rules
 static bool s_GroupStubsOfSameType;
 static bool s_IndividualAllocationStubReporting;
 static bool s_LogStubs; // If false, do not log stubs at all

 // Set to true if an error is encountered when writing to the file.
 static unsigned s_StubsMapped;
Expand DownExpand Up@@ -112,4 +159,5 @@ class PerfMap

 static bool LowGranularityStubs() { return !s_IndividualAllocationStubReporting; }
};
#endif // FEATURE_PERFMAP
#endif // PERFPID_H

85 changes: 58 additions & 27 deletions
src/coreclr/vm/virtualcallstub.cpp

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Original file line numberDiff line numberDiff line change
Expand Up@@ -10,9 +10,7 @@
#include "comdelegate.h"
#include <dn-stdio.h>

#ifdef FEATURE_PERFMAP
#include "perfmap.h"
#endif

#ifndef DACCESS_COMPILE

Expand DownExpand Up@@ -1051,7 +1049,19 @@ PCODE VirtualCallStubManager::GetCallStub(DispatchToken token)
 {
 if ((stub = (PCODE)(lookups->Find(&probeL))) == CALL_STUB_EMPTY_ENTRY)
 {
 LookupHolder *pLookupHolder = GenerateLookupStub(addrOfResolver, token.To_SIZE_T());
 LookupHolder *pLookupHolder;
 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
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 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pLookupHolder = GenerateLookupStub(addrOfResolver, token.To_SIZE_T());
 }

 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
 BOOL success = lookups->SetUpProber(token.To_SIZE_T(), 0, &probeL);
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 _ASSERTE(success);
 }
 stub = (PCODE) (lookups->Add((size_t)(pLookupHolder->stub()->entryPoint()), &probeL));
 }
 }
Expand DownExpand Up@@ -1082,7 +1092,20 @@ PCODE VirtualCallStubManager::GetVTableCallStub(DWORD slot)
 {
 if ((stub = (PCODE)(vtableCallers->Find(&probe))) == CALL_STUB_EMPTY_ENTRY)
 {
 VTableCallHolder *pHolder = GenerateVTableCallStub(slot);
 VTableCallHolder *pHolder;

 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pHolder = GenerateVTableCallStub(slot);
 }

 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
 BOOL success = vtableCallers->SetUpProber(DispatchToken::CreateDispatchToken(slot).To_SIZE_T(), 0, &probe);
 _ASSERTE(success);
 }
 stub = (PCODE)(vtableCallers->Add((size_t)(pHolder->stub()->entryPoint()), &probe));
 }
 }
Expand DownExpand Up@@ -1115,9 +1138,7 @@ VTableCallHolder* VirtualCallStubManager::GenerateVTableCallStub(DWORD slot)
 LOG((LF_STUBS, LL_INFO10000, "GenerateVTableCallStub for slot " FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(slot), DBG_ADDR(pHolder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateVTableCallStub", (PCODE)pHolder->stub(), pHolder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN(pHolder);
}
Expand DownExpand Up@@ -2054,14 +2075,24 @@ PCODE VirtualCallStubManager::ResolveWorker(StubCallSite* pCallSite,
 }
#endif // TARGET_X86 && !UNIX_X86_ABI

 pResolveHolder = GenerateResolveStub(pResolverFcn,
 pBackPatchFcn,
 token.To_SIZE_T()
 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pResolveHolder = GenerateResolveStub(pResolverFcn,
 pBackPatchFcn,
 token.To_SIZE_T()
#if defined(TARGET_X86) && !defined(UNIX_X86_ABI)
 , stackArgumentsSize
, stackArgumentsSize
#endif
 );
 }

 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
 BOOL success = resolvers->SetUpProber(token.To_SIZE_T(), 0, &probeR);
 _ASSERTE(success);
 }
 // Add the resolve entrypoint into the cache.
 //@TODO: Can we store a pointer to the holder rather than the entrypoint?
 resolvers->Add((size_t)(pResolveHolder->stub()->resolveEntryPoint()), &probeR);
Expand DownExpand Up@@ -2095,9 +2126,12 @@ PCODE VirtualCallStubManager::ResolveWorker(StubCallSite* pCallSite,
 if (addrOfDispatch == CALL_STUB_EMPTY_ENTRY)
 {
 PCODE addrOfFail = pResolveHolder->stub()->failEntryPoint();
 bool reenteredCooperativeGCMode = false;
 pDispatchHolder = GenerateDispatchStub(
 target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pDispatchHolder = GenerateDispatchStub(
 target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
 }
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 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
Expand DownExpand Up@@ -2208,9 +2242,12 @@ PCODE VirtualCallStubManager::ResolveWorker(StubCallSite* pCallSite,
 // so we may have to create it now
 ResolveHolder* pResolveHolder = ResolveHolder::FromResolveEntry(pCallSite->GetSiteTarget());
 PCODE addrOfFail = pResolveHolder->stub()->failEntryPoint();
 bool reenteredCooperativeGCMode = false;
 pDispatchHolder = GenerateDispatchStub(
 target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
 bool reenteredCooperativeGCMode = PerfMap::IsEnabled();
 {
 GCX_MAYBE_PREEMP(reenteredCooperativeGCMode);
 pDispatchHolder = GenerateDispatchStub(
 target, addrOfFail, objectType, token.To_SIZE_T(), &reenteredCooperativeGCMode);
 }
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 if (reenteredCooperativeGCMode)
 {
 // The prober may have been invalidated by reentering cooperative GC mode, reset it
Expand DownExpand Up@@ -2799,7 +2836,6 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStub(PCODE ad
 PRECONDITION(addrOfFail != NULL);
 PRECONDITION(CheckPointer(pMTExpected));
 PRECONDITION(pMayHaveReenteredCooperativeGCMode != nullptr);
 PRECONDITION(!*pMayHaveReenteredCooperativeGCMode);
 POSTCONDITION(CheckPointer(RETVAL));
 } CONTRACT_END;

Expand DownExpand Up@@ -2862,9 +2898,7 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStub(PCODE ad
 LOG((LF_STUBS, LL_INFO10000, "GenerateDispatchStub for token" FMT_ADDR "and pMT" FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(dispatchToken), DBG_ADDR(pMTExpected), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateDispatchStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN (holder);
}
Expand All@@ -2888,7 +2922,6 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStubLong(PCODE
 PRECONDITION(addrOfFail != NULL);
 PRECONDITION(CheckPointer(pMTExpected));
 PRECONDITION(pMayHaveReenteredCooperativeGCMode != nullptr);
 PRECONDITION(!*pMayHaveReenteredCooperativeGCMode);
 POSTCONDITION(CheckPointer(RETVAL));
 } CONTRACT_END;

Expand DownExpand Up@@ -2923,9 +2956,7 @@ DispatchHolder *VirtualCallStubManager::GenerateDispatchStubLong(PCODE
 LOG((LF_STUBS, LL_INFO10000, "GenerateDispatchStub for token" FMT_ADDR "and pMT" FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(dispatchToken), DBG_ADDR(pMTExpected), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateDispatchStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN (holder);
}
Expand DownExpand Up@@ -3021,9 +3052,7 @@ ResolveHolder *VirtualCallStubManager::GenerateResolveStub(PCODE addr
 LOG((LF_STUBS, LL_INFO10000, "GenerateResolveStub for token" FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(dispatchToken), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateResolveStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN (holder);
}
Expand DownExpand Up@@ -3054,9 +3083,7 @@ LookupHolder *VirtualCallStubManager::GenerateLookupStub(PCODE addrOfResolver, s
 LOG((LF_STUBS, LL_INFO10000, "GenerateLookupStub for token" FMT_ADDR "at" FMT_ADDR "\n",
 DBG_ADDR(dispatchToken), DBG_ADDR(holder->stub())));

#ifdef FEATURE_PERFMAP
 PerfMap::LogStubs(__FUNCTION__, "GenerateLookupStub", (PCODE)holder->stub(), holder->stub()->size(), PerfMapStubType::IndividualWithinBlock);
#endif

 RETURN (holder);
}
Expand DownExpand Up@@ -3084,8 +3111,12 @@ ResolveCacheElem *VirtualCallStubManager::GenerateResolveCacheElem(void *addrOfC
 CONSISTENCY_CHECK(CheckPointer(pMTExpected));

 //allocate from the requisite heap and set the appropriate fields
 ResolveCacheElem *e = (ResolveCacheElem*) (void*)
 ResolveCacheElem *e;
 {
 GCX_NOTRIGGER();
 e = (ResolveCacheElem*) (void*)
 cache_entry_heap->AllocAlignedMem(sizeof(ResolveCacheElem), CODE_SIZE_ALIGN);
 }

 e->pMT = pMTExpected;
 e->token = token;
Expand Down
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