more output, use OMP for simultaneous thread launch

Launching threads sequentially has a significant chance of giving a false negative. If an OMP parallel for construct is used to launch the concurrent calculations, then all threads start almost exactly at the same time, thus they have the highest chance of clashing.

cpp_thread_test/dgemm_thread_safety.cpp

@@ -2,11 +2,12 @@
 #include <vector>
 #include <random>
 #include <future>
+#include <omp.h>
 #include "/opt/OpenBLAS_zen_serial/include/cblas.h"
 
 const blasint randomMatSize = 1024; //dimension of the random square matrices used
-const uint32_t numConcurrentThreads = 64; //number of concurrent calls of the functions being tested
+const uint32_t numConcurrentThreads = 52; //number of concurrent calls of the functions being tested
-const uint32_t numTestRounds = 32; //number of testing rounds before success exit
+const uint32_t numTestRounds = 8; //number of testing rounds before success exit
 
 inline void pauser(){
     /// a portable way to pause a program
@@ -60,6 +61,14 @@ int main(){
 	std::vector<std::vector<double>> matBlock(numConcurrentThreads*3);
 	std::vector<std::future<void>> futureBlock(numConcurrentThreads);
 	
+	std::cout<<"*----------------------------*\n";
+	std::cout<<"| DGEMM thread safety tester |\n";
+	std::cout<<"*----------------------------*\n";
+	std::cout<<"Size of random matrices(N=M=K): "<<randomMatSize<<'\n';
+	std::cout<<"Number of concurrent calls into OpenBLAS : "<<numConcurrentThreads<<'\n';
+	std::cout<<"Number of testing rounds : "<<numTestRounds<<'\n';
+	std::cout<<"This test will need "<<(static_cast<uint64_t>(randomMatSize*randomMatSize)*numConcurrentThreads*3*8)/static_cast<double>(1024*1024)<<" MiB of RAM\n"<<std::endl;
+	
 	std::cout<<"Initializing random number generator..."<<std::flush;
 	std::mt19937_64 PRNG = InitPRNG();
 	std::cout<<"done\n";
@@ -70,14 +79,17 @@ int main(){
 		matBlock[i].resize(randomMatSize*randomMatSize);
 	}
 	std::cout<<"done\n";
+	//pauser();
 	std::cout<<"Filling matrices with random numbers..."<<std::flush;
 	FillMatrices(matBlock, PRNG, rngdist);
 	//PrintMatrices(matBlock);
 	std::cout<<"done\n";
 	std::cout<<"Testing CBLAS DGEMM thread safety\n";
+	omp_set_num_threads(numConcurrentThreads);
 	for(uint32_t R=0; R<numTestRounds; R++){
 		std::cout<<"DGEMM round #"<<R<<std::endl;
 		std::cout<<"Launching "<<numConcurrentThreads<<" threads..."<<std::flush;
+		#pragma omp parallel for default(none) shared(futureBlock, matBlock)
 		for(uint32_t i=0; i<numConcurrentThreads; i++){
 			futureBlock[i] = std::async(std::launch::async, launch_cblas_dgemm, &matBlock[i*3][0], &matBlock[i*3+1][0], &matBlock[i*3+2][0]);
 			//launch_cblas_dgemm( &matBlock[i][0], &matBlock[i+1][0], &matBlock[i+2][0]);
@@ -94,11 +106,13 @@ int main(){
 			for(uint32_t j=0; j<(randomMatSize*randomMatSize); j++){
 				if (std::abs(matBlock[i+2][j] - matBlock[2][j]) > 1.0E-13){
 					std::cout<<"ERROR: one of the threads returned a different result!"<<i+2<<std::endl;
+					std::cout<<"CBLAS DGEMM thread safety test FAILED!"<<std::endl;
 					return -1;
 				}
 			}
 		}
 		std::cout<<"OK!"<<std::endl;
 	}
+	std::cout<<"CBLAS DGEMM thread safety test PASSED!"<<std::endl;
 	return 0;
 }