Date: Fri, 28 Oct 2005 18:30:22 +0800 From: David Xu <davidxu@freebsd.org> To: David Xu <davidxu@freebsd.org> Cc: Pertti Kosunen <pertti.kosunen@pp.nic.fi>, Poul-Henning Kamp <phk@phk.freebsd.dk>, current@freebsd.org, "Yuriy N. Shkandybin" <jura@networks.ru> Subject: Re: Timers and timing, was: MySQL Performance 6.0rc1 Message-ID: <4361FDBE.7000500@freebsd.org> In-Reply-To: <4361FA1C.1070103@freebsd.org> References: <30622.1130493370@critter.freebsd.dk> <4361FA1C.1070103@freebsd.org>
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David Xu wrote: > Poul-Henning Kamp wrote: > >> In message <4361F057.4030904@pp.nic.fi>, Pertti Kosunen writes: >> >> >>> Does polling affect to this test? >> >> >> >> Not apart from the CPU overhead. >> >> sysctl kern.timecounter.hardware >> >> is much more important. >> >> and all the reports here which fail to include it are mostly >> useless. >> >> > I suspect because our time() function in libc uses gettimeofday, > this further causes lots of gettimeofday syscall. > > Now, I can confirm mysqld calls time() function lots of time, I have changed time() to call clock_gettime, now there is few of gettimeofday in ktrace result, but fully filled by clock_gettime. Can we optimize time()? because it only returns second. may we just create a syscall to return time_second variable in kernel, this sounds crazy though.
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