ParallelAlgorithms/ParallelStdCppExample.cpp at master · DragonSpit/ParallelAlgorithms · GitHub

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// From https://blogs.msdn.microsoft.com/vcblog/2018/09/11/using-c17-parallel-algorithms-for-better-performance/
// compile with:
// debug: cl /EHsc /W4 /WX /std:c++latest /Fedebug /MDd .\program.cpp
// release: cl /EHsc /W4 /WX /std:c++latest /Ferelease /MD /O2 .\program.cpp
//#include <oneapi/dpl/execution>
//#include <oneapi/dpl/algorithm>
#include<iostream>
#include<algorithm>
#include<chrono>
#include<random>
#include<ratio>
#include<vector>
#include<execution>
//#include <pstl/execution> // TBB
//#include <pstl/algorithm> // TBB

using std::chrono::duration;
using std::chrono::duration_cast;
using std::chrono::high_resolution_clock;
using std::milli;
using std::random_device;
using std::sort;
using std::vector;

constint iterationCount = 5;

voidprint_results(constchar *const tag, const vector<double>& sorted,
	high_resolution_clock::time_point startTime,
	high_resolution_clock::time_point endTime)
{
printf("%s: Lowest: %g Highest: %g Time: %fms\n", tag, sorted.front(), sorted.back(),
 duration_cast<duration<double, milli>>(endTime - startTime).count());
}

voidprint_results(constchar* const tag, const vector<unsignedlong>& sorted,
	high_resolution_clock::time_point startTime,
	high_resolution_clock::time_point endTime)
{
printf("%s: Lowest: %lu Highest: %lu Time: %fms\n", tag, sorted.front(), sorted.back(),
 duration_cast<duration<double, milli>>(endTime - startTime).count());
	std::cout << tag << ": Lowest: " << sorted.front() << "" << sizeof(sorted.front()) << std::endl;
}

voidprint_results(constchar* const tag, const vector<unsigned>& sorted,
	high_resolution_clock::time_point startTime,
	high_resolution_clock::time_point endTime)
{
printf("%s: Lowest: %u Highest: %u Time: %fms\n", tag, sorted.front(), sorted.back(),
 duration_cast<duration<double, milli>>(endTime - startTime).count());
}

voidprint_results(constchar *const tag, double first, double last,
	high_resolution_clock::time_point startTime,
	high_resolution_clock::time_point endTime)
{
printf("%s: Lowest: %g Highest: %g Time: %fms\n", tag, first, last,
 duration_cast<duration<double, milli>>(endTime - startTime).count());
}

intParallelStdCppExample(vector<double>& doubles)
{
// time how long it takes to sort them:
for (int i = 0; i < iterationCount; ++i)
	{
 vector<double> sorted(doubles);
constauto startTime = high_resolution_clock::now();
sort(sorted.begin(), sorted.end());
constauto endTime = high_resolution_clock::now();
print_results("Serial", sorted, startTime, endTime);
	}

for (int i = 0; i < iterationCount; ++i)
	{
 vector<double> sorted(doubles);
constauto startTime = high_resolution_clock::now();
// same sort call as above, but with par_unseq:
sort(std::execution::par_unseq, sorted.begin(), sorted.end());
constauto endTime = high_resolution_clock::now();
// in our output, note that these are the parallel results:
print_results("Parallel", sorted, startTime, endTime);
	}

for (int i = 0; i < iterationCount; ++i)
	{
double * s = newdouble[doubles.size()];
for (size_t j = 0; j < doubles.size(); j++) {	// copy the original random array into the source array each time, since ParallelMergeSort modifies the source array while sorting
 s[j] = doubles[j];
 }
constauto startTime = high_resolution_clock::now();
sort(std::execution::par_unseq, s, s+doubles.size());
constauto endTime = high_resolution_clock::now();
print_results("Parallel Array", s[0], s[doubles.size() - 1], startTime, endTime);
delete[] s;
	}

return0;
}

intParallelStdCppExample(vector<unsigned>& uints, bool stable = false)
{
// time how long it takes to sort them:
for (int i = 0; i < iterationCount; ++i)
	{
 vector<unsigned> sorted(uints);
constauto startTime = high_resolution_clock::now();
if (!stable)
sort(sorted.begin(), sorted.end());
else
stable_sort(sorted.begin(), sorted.end());
constauto endTime = high_resolution_clock::now();
print_results("Serial", sorted, startTime, endTime);
	}
#if0
	for (int i = 0; i < iterationCount; ++i)
	{
 vector<unsigned> sorted(uints);
 const auto startTime = high_resolution_clock::now();
 // same sort call as above, but with par_unseq:
 if (!stable)
 sort(std::execution::par_unseq, sorted.begin(), sorted.end());
 else
 stable_sort(std::execution::par_unseq, sorted.begin(), sorted.end());
 const auto endTime = high_resolution_clock::now();
 // in our output, note that these are the parallel results:
 print_results("Parallel", sorted, startTime, endTime);
	}

	for (int i = 0; i < iterationCount; ++i)
	{
 unsigned* s = new unsigned[uints.size()];
 for (size_t j = 0; j < uints.size(); j++) {	// copy the original random array into the source array each time, since ParallelMergeSort modifies the source array while sorting
 s[j] = uints[j];
 }
 const auto startTime = high_resolution_clock::now();
 if (!stable)
 sort(std::execution::par_unseq, s, s + uints.size());
 else
 std::stable_sort(std::execution::par_unseq, s, s + uints.size());
 const auto endTime = high_resolution_clock::now();
 print_results("Parallel Array", s[0], s[uints.size() - 1], startTime, endTime);
 delete[] s;
	}
#endif
return0;
}

intParallelStdCppExample(vector<unsigned>& uints)
{
// time how long it takes to sort them:
for (int i = 0; i < iterationCount; ++i)
	{
 vector<unsigned> sorted(uints);
constauto startTime = high_resolution_clock::now();
sort(sorted.begin(), sorted.end());
constauto endTime = high_resolution_clock::now();
print_results("Serial", sorted, startTime, endTime);
	}

for (int i = 0; i < iterationCount; ++i)
	{
 vector<unsigned> sorted(uints);
constauto startTime = high_resolution_clock::now();
// same sort call as above, but with par_unseq:
sort(std::execution::par_unseq, sorted.begin(), sorted.end());
constauto endTime = high_resolution_clock::now();
// in our output, note that these are the parallel results:
print_results("Parallel", sorted, startTime, endTime);
	}

for (int i = 0; i < iterationCount; ++i)
	{
unsigned *s = newunsigned[uints.size()];
for (size_t j = 0; j < uints.size(); j++) {	// copy the original random array into the source array each time, since ParallelMergeSort modifies the source array while sorting
 s[j] = uints[j];
 }
constauto startTime = high_resolution_clock::now();
sort(std::execution::par_unseq, s, s + uints.size());
constauto endTime = high_resolution_clock::now();
print_results("Parallel Array", s[0], s[uints.size() - 1], startTime, endTime);
delete[] s;
	}

printf("\nAccumulate/Sum Benchmark:\n");

for (int i = 0; i < iterationCount; ++i)
	{
unsigned* s = newunsigned[uints.size()];
for (size_t j = 0; j < uints.size(); j++) {	// copy the original random array into the source array each time, since ParallelMergeSort modifies the source array while sorting
 s[j] = uints[j];
 }
constauto startTime = high_resolution_clock::now();
unsigned result_serial = std::accumulate(s, s + uints.size(), 0);
constauto endTime = high_resolution_clock::now();
print_results("Serial Array Sum", result_serial, result_serial, startTime, endTime);
delete[] s;
	}
for (int i = 0; i < iterationCount; ++i)
	{
unsigned* s = newunsigned[uints.size()];
for (size_t j = 0; j < uints.size(); j++) {	// copy the original random array into the source array each time, since ParallelMergeSort modifies the source array while sorting
 s[j] = uints[j];
 }
constauto startTime = high_resolution_clock::now();
unsigned result_parallel = std::reduce(std::execution::par, s, s + uints.size(), 0); //Faster
constauto endTime = high_resolution_clock::now();
print_results("Parallel Array Sum", result_parallel, result_parallel, startTime, endTime);
delete[] s;
	}

return0;
}