system call performance 4.x vs 5.x [and UP vs MP]
Robert Watson
rwatson at freebsd.org
Wed Jan 28 12:59:18 PST 2004
On Wed, 28 Jan 2004, Robert Watson wrote:
> printf("%d.%09lu for %d iterations\n", ts_end.tv_sec,
> ts_end.tv_nsec, NUM);
> printf("%d.%09lu per/iteration\n", ts_end.tv_sec / NUM,
> ts_end.tv_nsec / NUM);
Having posted this, I should point out that this suffers an error if you
get above a second total measurement time (which I generally don't do to
avoid being preempted). Something like the following would work slightly
better:
ts_end.tv_sec *= 1000000000 / count;
printf("0.%09lu per/iteration\n", ts_end.tv_sec +
ts_end.tv_nsec / count);
Robert N M Watson FreeBSD Core Team, TrustedBSD Projects
robert at fledge.watson.org Senior Research Scientist, McAfee Research
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