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loop.c loop.c 2013/06/08 11:07 current
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 +<code c>
 +/*
 +** CPU-bound test
 +*/
 +#include <sys/types.h>
 +#include <sys/time.h>
 +#include <sys/resource.h>
 +#include <err.h>
 +#include <stdlib.h>
 +#include <stdio.h>
 +#include <unistd.h>
 +void runit(double y, int fd, size_t len)
 +{
 + double  x;
 + double *bp;
 + size_t i;
 + char ch;
 +
 + bp = malloc(len);
 + len /= sizeof(double);
 + for (i = 0; i < len; i++)
 +     bp[i] = 1.0;
 + if (write(fd, "x", 1) != 1)
 +     err(1, "write1");
 + if (read(fd, &ch, 1) != 1)
 +     err(1, "read1");
 + i = 0;
 + for (x = 0.0; x < y; x += 1.0) {
 +     bp[i] += x;
 +     if (++i >= len)
 + i = 0;
 + }
 + exit(0);
 +}
 +
 +int main(int argc, char **argv)
 +{
 + double y;
 + pid_t p;
 + int i, j, x;
 + struct timeval start, end;
 + struct rusage usage;
 + int fds[2];
 + size_t len;
 + char *buf;
 +
 + i = strtol(argv[1], NULL, 0);
 + y = strtod(argv[2], NULL);
 + len = strtoul(argv[3], NULL, 0) * 1024;
 +
 + if (pipe(fds) < 0)
 +     err(1, "pipe");
 +
 + buf = malloc(i);
 + for (j = 0; j < i; j++) {
 + p = fork();
 + if (p < 0)
 + err(1, "fork");
 + else if (p == 0)
 + runit(y, fds[1], len);
 + }
 + for (j = 0; j < i; j++) {
 +     if (read(fds[0], buf, 1) != 1)
 + err(1, "read0");
 + }
 + if (write(fds[0], buf, i) != i)
 +     err(1, "write0");
 +
 + gettimeofday(&start, NULL);
 + while (wait(&x) > 0)
 + ;
 + gettimeofday(&end, NULL);
 + getrusage(RUSAGE_CHILDREN, &usage);
 +
 + end.tv_sec -= start.tv_sec;
 + end.tv_usec -= start.tv_usec;
 + if (end.tv_usec < 0) {
 + end.tv_usec += 1000000;
 + end.tv_sec--;
 + }
 +
 + printf("%d %g %ld.%06ld %ld.%06ld %ld.%06ld\n", i, y,
 + end.tv_sec, end.tv_usec,
 + usage.ru_utime.tv_sec, usage.ru_utime.tv_usec,
 + usage.ru_stime.tv_sec, usage.ru_stime.tv_usec);
 + return 0;
 +}
 +</code>
 
loop.c.txt · Last modified: 2013/06/08 11:07 by peterjeremy
 
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