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The cmraw tool shows the approximate minimum time a program could nanosleep, which tends to be quite a bit bigger than the smallest value one could pass to nanosleep (one ns). For example, on my i7-3770 running linux, the results tend to be between 90 and 120 ns.
36 lines
837 B
C
36 lines
837 B
C
/* Show approximate minimum clock resolution
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Derived from the example in the linux man page for clock_gettime() */
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#define _XOPEN_SOURCE 600
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#include <time.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdbool.h>
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#include <unistd.h>
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static void displayClock(clockid_t clock, char *name)
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{
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struct timespec ts;
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time_t oldsec;
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long oldnsec;
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clock_gettime(clock, &ts);
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oldsec = ts.tv_sec;
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oldnsec = ts.tv_nsec;
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while (ts.tv_sec == oldsec && ts.tv_nsec == oldnsec)
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{
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if (clock_gettime(clock, &ts) == -1) {
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perror("clock_gettime");
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exit(EXIT_FAILURE);
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}
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}
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printf("%-15s: %10ld sec %09ld nsec\n", name,
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(long) ts.tv_sec - oldsec, ts.tv_nsec - oldnsec);
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}
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int main(int argc, char *argv[])
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{
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displayClock(CLOCK_MONOTONIC_RAW, "CLOCK_MONOTONIC_RAW");
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exit(0);
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}
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