cosmopolitan/tool/viz/clock_accuracy.c
2023-10-11 21:45:32 -07:00

44 lines
1.7 KiB
C

#if 0
/*─────────────────────────────────────────────────────────────────╗
│ To the extent possible under law, Justine Tunney has waived │
│ all copyright and related or neighboring rights to this file, │
│ as it is written in the following disclaimers: │
│ • http://unlicense.org/ │
│ • http://creativecommons.org/publicdomain/zero/1.0/ │
╚─────────────────────────────────────────────────────────────────*/
#endif
#include "libc/calls/calls.h"
#include "libc/calls/struct/timespec.h"
#include "libc/runtime/runtime.h"
#include "libc/stdio/stdio.h"
/**
* @fileoverview clock() function demo
*/
int main(int argc, char *argv[]) {
ShowCrashReports();
unsigned long i;
volatile unsigned long x;
struct timespec now, start, next, interval;
printf("hammering the cpu...\n");
next = start = timespec_mono();
interval = timespec_frommillis(500);
next = timespec_add(next, interval);
for (;;) {
for (i = 0;; ++i) {
x *= 7;
if (!(i % 256)) {
now = timespec_mono();
if (timespec_cmp(now, next) >= 0) {
break;
}
}
}
next = timespec_add(next, interval);
printf("consumed %10g seconds monotonic time and %10g seconds cpu time\n",
timespec_tonanos(timespec_sub(now, start)) / 1000000000.,
(double)clock() / CLOCKS_PER_SEC);
}
}