PthreadsNg: setAffinities algorithm assumes taskset is used (fa9e0e1a) · Commits · Alvarez, Gonzalo / PsimagLite

src/PthreadsNg.h

+68 −19

Original line number	Diff line number	Diff line
		@@ -154,23 +154,7 @@ public:
		: nthreads_(codeSectionParams.npthreads),
		setAffinities_(codeSectionParams.setAffinities),
		stackSize_(codeSectionParams.stackSize)
		{
		#ifndef __APPLE__
		cpu_set_t cpuset;
		static bool firstCall = true;
		if (setAffinities_) {
		pid_t pid = getpid(); // always successfull
		getPidAffinity(&cpuset, pid);
		int ret = sched_setaffinity(pid, sizeof(cpu_set_t), &cpuset);
		checkForError(ret);
		if (ret == 0 && firstCall) {
		std::cout<<"pid "<<pid<<" sched_setaffinity with count ";
		std::cout<<CPU_COUNT(&cpuset)<<"\n";
		firstCall = false;
		}
		}
		#endif
		}
		{}

		bool affinities() const { return setAffinities_; }

		@@ -221,6 +205,23 @@ public:
		pthread_attr_t** attr = new pthread_attr_t*[nthreads_];
		SizeType ntasks = pfh.tasks();

		cpu_set_t cpuset;

		#ifndef __APPLE__

		if (setAffinities_) {
		static bool firstCall = true;
		pid_t pid = getpid(); // always successfull
		getPidAffinity(&cpuset, pid);
		int ret = sched_setaffinity(pid, sizeof(cpu_set_t), &cpuset);
		checkForError(ret);
		if (ret == 0 && firstCall) {
		printAffinity(pid, &cpuset);
		firstCall = false;
		}
		}
		#endif

		for (SizeType j=0; j <nthreads_; j++) {
		pfs[j].pfh = &pfh;
		pfs[j].loadBalancer = &loadBalancer;
		@@ -243,8 +244,8 @@ public:
		ret = pthread_attr_init(attr[j]);
		checkForError(ret);

		//if (setAffinities_)
		// setAffinity(attr[j], &cpuset, j);
		if (setAffinities_)
		setAffinity(attr[j], &cpuset, j);

		ret = pthread_create(&thread_id[j],
		attr[j],
		@@ -285,6 +286,54 @@ private:
		}
		}

		void setAffinity(pthread_attr_t* attr, cpu_set_t* cpuset, SizeType threadNum) const
		{
		// pick a cpu from cpuset
		int chosenCpu = getOneCpuFromSet(cpuset);
		if (chosenCpu < 0) {
		std::cerr<<"setAffinity: no cpus left in set for thread "<<threadNum<<"\n";
		return;
		}

		cpu_set_t mynewset;
		CPU_ZERO(&mynewset);
		CPU_SET(chosenCpu, &mynewset); // add cpu to new set
		int ret = pthread_attr_setaffinity_np(attr, sizeof(cpu_set_t), &mynewset);
		checkForError(ret);
		if (ret != 0)
		return;

		// remove cpu from set
		CPU_CLR(chosenCpu, cpuset);
		}

		int getOneCpuFromSet(cpu_set_t* cpuset) const
		{
		int count = CPU_COUNT(cpuset);
		if (count == 0) return -1;

		int chosenCpu = -1;
		for (int i = 0; i < MAX_CPUS; ++i) {
		if (CPU_ISSET(i, cpuset) == 0) continue;
		chosenCpu = i;
		break;
		}

		return chosenCpu;
		}

		void printAffinity(pid_t pid, cpu_set_t* cpuset) const
		{
		std::cout<<"pid "<<pid<<" sched_setaffinity with count ";
		std::cout<<CPU_COUNT(cpuset)<<": ";
		for (int i = 0; i < MAX_CPUS; ++i) {
		if (CPU_ISSET(i, cpuset) == 0) continue;
		std::cout<<i<<" ";
		}

		std::cout<<"\n";
		}

		void checkForError(int ret) const
		{
		if (ret == 0) return;