From 7ff47c5e41aad0568cc6748e39df6f04eb4280f0 Mon Sep 17 00:00:00 2001
From: Jarek Potiuk <jarek@potiuk.com>
Date: Mon, 22 Jun 2026 00:30:47 -0400
Subject: [PATCH] Reduce canary schedule frequency (AMD 4->2/day, ARM 8->2/day)

The scheduled canary runs the full matrix on all versions and is by far the most
expensive run type. AMD ran 4x/day and ARM 8x/day; halving AMD alone saves
~1,900 compute-h / 2 weeks (~6% of AMD CI), and cutting ARM 8->2/day removes 75%
of the ARM canary schedule.

The two crons are interleaved (AMD 01:58 & 13:58, ARM 07:28 & 19:28) so a
full-matrix canary still runs roughly every ~6h, alternating architecture - so
the 'trust earned on main' backstop keeps a ~6h effective cadence for
arch-agnostic regressions (12h for arch-specific ones) while the scheduled
compute drops substantially. It also relieves runner-pool queuing, since each
canary is the heaviest job-flood.

check_ci_workflows_in_sync.py expected blocks updated to match.
---
 .github/workflows/ci-amd.yml                  |  9 +++++----
 .github/workflows/ci-arm.yml                  |  6 +++++-
 scripts/ci/prek/check_ci_workflows_in_sync.py | 15 ++++++++++-----
 3 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/.github/workflows/ci-amd.yml b/.github/workflows/ci-amd.yml
index 43276945a9c69..3e7635a6a94c6 100644
--- a/.github/workflows/ci-amd.yml
+++ b/.github/workflows/ci-amd.yml
@@ -26,10 +26,11 @@
 name: Tests (AMD)
 on:  # yamllint disable-line rule:truthy
   schedule:
-    # Mirror of the previous AMD canary cron from before the AMD/ARM split (PR #66348),
-    # offset by 30 min from ARM's `:28` slot in `ci-arm.yml` so the two scheduled
-    # canaries don't compete for runners at exactly the same minute.
-    - cron: '58 1,7,13,19 * * *'
+    # AMD canary runs 2x/day (01:58, 13:58), interleaved with ARM's 2x/day (07:28, 19:28)
+    # in `ci-arm.yml` so a full-matrix canary still runs roughly every ~6h (alternating
+    # architecture) while halving the scheduled AMD compute. The `:58` vs ARM's `:28`
+    # offset keeps the two from competing for runners at exactly the same minute.
+    - cron: '58 1,13 * * *'
   pull_request:
     branches:
       - main
diff --git a/.github/workflows/ci-arm.yml b/.github/workflows/ci-arm.yml
index 688408aa8e49d..8c752cbb19179 100644
--- a/.github/workflows/ci-arm.yml
+++ b/.github/workflows/ci-arm.yml
@@ -26,7 +26,11 @@
 name: Tests (ARM)
 on:  # yamllint disable-line rule:truthy
   schedule:
-    - cron: '28 1,3,7,9,13,15,19,21 * * *'
+    # ARM canary runs 2x/day (07:28, 19:28), interleaved with AMD's 2x/day (01:58, 13:58)
+    # in `ci-amd.yml` so a full-matrix canary still runs roughly every ~6h (alternating
+    # architecture). The `:28` vs AMD's `:58` offset keeps the two from competing for
+    # runners at exactly the same minute.
+    - cron: '28 7,19 * * *'
   push:
     # Post-merge pushes to release-prep / providers branches run on both
     # AMD and ARM (the matching block lives in the other wrapper too —
diff --git a/scripts/ci/prek/check_ci_workflows_in_sync.py b/scripts/ci/prek/check_ci_workflows_in_sync.py
index b64600cd16576..d6116d856b8bf 100755
--- a/scripts/ci/prek/check_ci_workflows_in_sync.py
+++ b/scripts/ci/prek/check_ci_workflows_in_sync.py
@@ -107,14 +107,19 @@
 # file and must NOT appear in the other. The blocks are stripped before
 # diffing so they don't show up as drift.
 ARM_ONLY_BLOCK = """  schedule:
-    - cron: '28 1,3,7,9,13,15,19,21 * * *'
+    # ARM canary runs 2x/day (07:28, 19:28), interleaved with AMD's 2x/day (01:58, 13:58)
+    # in `ci-amd.yml` so a full-matrix canary still runs roughly every ~6h (alternating
+    # architecture). The `:28` vs AMD's `:58` offset keeps the two from competing for
+    # runners at exactly the same minute.
+    - cron: '28 7,19 * * *'
 """
 
 AMD_ONLY_BLOCK = """  schedule:
-    # Mirror of the previous AMD canary cron from before the AMD/ARM split (PR #66348),
-    # offset by 30 min from ARM's `:28` slot in `ci-arm.yml` so the two scheduled
-    # canaries don't compete for runners at exactly the same minute.
-    - cron: '58 1,7,13,19 * * *'
+    # AMD canary runs 2x/day (01:58, 13:58), interleaved with ARM's 2x/day (07:28, 19:28)
+    # in `ci-arm.yml` so a full-matrix canary still runs roughly every ~6h (alternating
+    # architecture) while halving the scheduled AMD compute. The `:58` vs ARM's `:28`
+    # offset keeps the two from competing for runners at exactly the same minute.
+    - cron: '58 1,13 * * *'
   pull_request:
     branches:
       - main