94 lines
2.5 KiB
C
94 lines
2.5 KiB
C
#include <assert.h>
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <time.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include <sys/wait.h>
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#define N 5
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typedef struct {
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double time;
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size_t nread;
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} resultT;
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int cmptime(const void *a, const void *b) {
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const resultT *aa = a, *bb = b;
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if (aa->time < bb->time) {
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return -1;
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} else if (aa->time > bb->time) {
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return +1;
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} else {
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return 0;
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}
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}
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resultT median (resultT *v, int n) {
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// n is small, keep it simple
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qsort(v, n, sizeof(*v), cmptime);
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return v[n / 2];
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}
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int main(int argc, char **argv) {
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resultT **results = calloc(sizeof(*results), argc);
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assert(results);
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for (int i = 1; i < argc; i++) {
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results[i] = calloc(sizeof(**results), N);
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assert(results[i]);
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}
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for (int j = 0; j < N; j++) {
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for (int i = 1; i < argc; i++) {
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struct timespec t0, t1;
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clock_gettime(CLOCK_MONOTONIC, &t0);
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size_t nread = 0;
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int out[2];
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if (pipe(out) == -1) {
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printf("%s: cannot create pipe: %s\n", argv[0], strerror(errno));
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exit(1);
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}
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pid_t pid = fork();
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switch(pid) {
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case -1:
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fprintf(stderr, "%s: cannot fork: %s\n", argv[0], strerror(errno));
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exit(1);
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case 0:
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dup2(out[1], 1);
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// close(out[0]);
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// close(out[1]);
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execl(argv[i], argv[i], (char *)NULL);
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fprintf(stderr, "%s: cannot exec %s: %s\n", argv[0], argv[i], strerror(errno));
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exit(1);
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default: {
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close(out[1]);
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ssize_t n;
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char buf[16];
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while ((n = read(out[0], buf, sizeof(buf))) > 0) {
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nread += n;
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}
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int status;
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while (waitpid(pid, &status, 0) != pid);
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}
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}
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clock_gettime(CLOCK_MONOTONIC, &t1);
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results[i][j].time = (t1.tv_sec - t0.tv_sec) * 1E9 + (t1.tv_nsec - t0.tv_nsec);
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results[i][j].nread = nread;
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fprintf(stderr, "%s: %s completed in %f ns\n", argv[0], argv[i], results[i][j].time);
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}
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}
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for (int i = 1; i < argc; i++) {
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resultT m = median(results[i], N);
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printf("%-20s %8.3f ms %2d bytes\n", argv[i], m.time / 1E6, m.nread);
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}
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return 0;
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}
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