pipe.c

#include <unistd.h>
#include <fcntl.h>
#include <pthread.h>
#include <stdio.h>

static double getsec()
{
    struct timespec ts;

    clock_gettime(CLOCK_MONOTONIC, &ts);
    return ts.tv_sec + ts.tv_nsec/1e9;
}

struct shared {
    int n;
    int p0[2], p1[2];
};

void *t0(void *p)
{
    struct shared *s = (struct shared*)p;
    int i;
    int n = s->n;
    for (int i=0; i<n; i++) {
        char b;

        read(s->p0[0], &b, 1);
        write(s->p1[1], &b, 1);
    }
}

void test(struct shared *sd)
{
    pthread_t pt;

    pthread_create(&pt, NULL,
                   t0, sd);

    int n = sd->n;

    double t0 = getsec();
    for (int i=0; i<n; i++) {
        char b=4;
        write(sd->p0[1], &b, 1);
        read(sd->p1[0], &b, 1);
    }
    double t1 = getsec();

    printf("%f[ns]\n", ((t1-t0)/sd->n)*1e9);

    pthread_join(pt, NULL);
    
}

int main()
{
    struct shared sd;
    int n = 65536;

    sd.n = n;

    pipe(sd.p0);
    pipe(sd.p1);

    test(&sd);
    test(&sd);
    
}