source: benchmark/readyQ/cycle.cc@ 8e4f34e

#include "rq_bench.hpp"

#include <pthread.h>
#include <semaphore.h>
#include <sched.h>
#include <unistd.h>

struct Pthread {
        static int usleep(useconds_t usec) {
                return ::usleep(usec);
        }
};

struct Partner {
        unsigned long long count  = 0;
        unsigned long long blocks = 0;
        sem_t self;
        sem_t * next;
};

void partner_main( Partner * self ) {
        self->count = 0;
        for(;;) {
                sem_wait(&self->self);
                sem_post(self->next);
                self->count ++;
                if( clock_mode && stop) break;
                if(!clock_mode && self->count >= stop_count) break;

                int sval;
                sem_getvalue(&self->self, &sval);
                if(sval > 1) std::abort();
                if(sval < 0) std::abort();
        }

        __atomic_fetch_add(&threads_left, -1, __ATOMIC_SEQ_CST);
}

int main(int argc, char * argv[]) {
        unsigned ring_size = 2;
        option_t opt[] = {
                BENCH_OPT,
                { 'r', "ringsize", "Number of threads in a cycle", ring_size }
        };
        BENCH_OPT_PARSE("cforall cycle benchmark");

        {
                unsigned long long global_counter = 0;
                unsigned long long global_blocks  = 0;
                unsigned tthreads = nthreads * ring_size;
                uint64_t start, end;

                {
                        cpu_set_t cpuset;
                        int ret = pthread_getaffinity_np( pthread_self(), sizeof(cpuset), &cpuset );
                        if(ret != 0) std::abort();

                        unsigned cnt = CPU_COUNT_S(sizeof(cpuset), &cpuset);
                        if(cnt > nprocs) {
                                unsigned extras = cnt - nprocs;
                                for(int i = 0; i < CPU_SETSIZE && extras > 0; i++) {
                                        if(CPU_ISSET_S(i, sizeof(cpuset), &cpuset)) {
                                                CPU_CLR_S(i, sizeof(cpuset), &cpuset);
                                                extras--;
                                        }
                                }

                                ret = pthread_setaffinity_np( pthread_self(), sizeof(cpuset), &cpuset );
                                if(ret != 0) std::abort();
                        }
                }

                {
                        threads_left = tthreads;
                        pthread_t threads[tthreads];
                        Partner thddata[tthreads];
                        for(int i = 0; i < tthreads; i++) {
                                int ret = sem_init( &thddata[i].self, false, 0 );
                                if(ret != 0) std::abort();

                                unsigned pi = (i + nthreads) % tthreads;
                                thddata[i].next = &thddata[pi].self;
                        }
                        for(int i = 0; i < tthreads; i++) {
                                int ret = pthread_create( &threads[i], nullptr, reinterpret_cast<void * (*)(void *)>(partner_main), &thddata[i] );
                                if(ret != 0) std::abort();
                        }
                        printf("Starting\n");

                        bool is_tty = isatty(STDOUT_FILENO);
                        start = timeHiRes();

                        for(int i = 0; i < nthreads; i++) {
                                sem_post(&thddata[i].self);
                        }
                        wait<Pthread>(start, is_tty);

                        stop = true;
                        end = timeHiRes();
                        printf("\nDone\n");

                        for(int i = 0; i < tthreads; i++) {
                                sem_post(&thddata[i].self);
                                int ret = pthread_join( threads[i], nullptr );
                                if(ret != 0) std::abort();
                                global_counter += thddata[i].count;
                                global_blocks  += thddata[i].blocks;
                        }

                        for(int i = 0; i < tthreads; i++) {
                                int ret = sem_destroy( &thddata[i].self );
                                if(ret != 0) std::abort();
                        }
                }

                printf("Duration (ms)        : %'ld\n", to_miliseconds(end - start));
                printf("Number of processors : %'d\n", nprocs);
                printf("Number of threads    : %'d\n", tthreads);
                printf("Cycle size (# thrds) : %'d\n", ring_size);
                printf("Total Operations(ops): %'15llu\n", global_counter);
                printf("Total blocks         : %'15llu\n", global_blocks);
                printf("Ops per second       : %'18.2lf\n", ((double)global_counter) / to_fseconds(end - start));
                printf("ns per ops           : %'18.2lf\n", ((double)(end - start)) / global_counter);
                printf("Ops per threads      : %'15llu\n", global_counter / tthreads);
                printf("Ops per procs        : %'15llu\n", global_counter / nprocs);
                printf("Ops/sec/procs        : %'18.2lf\n", (((double)global_counter) / nprocs) / to_fseconds(end - start));
                printf("ns per ops/procs     : %'18.2lf\n", ((double)(end - start)) / (global_counter / nprocs));
                fflush(stdout);
        }

        return 0;
}