Date: Fri, 28 Oct 2005 14:58:28 +0200 From: Bernd Walter <ticso@cicely12.cicely.de> 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: <20051028125828.GE66456@cicely12.cicely.de> In-Reply-To: <436200BE.70604@freebsd.org> References: <31129.1130495688@critter.freebsd.dk> <436200BE.70604@freebsd.org>
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On Fri, Oct 28, 2005 at 06:43:10PM +0800, David Xu wrote: > Poul-Henning Kamp wrote: > >In message <4361FDBE.7000500@freebsd.org>, David Xu writes: > > > > > >the correct way to optimize this would be to add a time(2) systemcall > >which returns the value of the kernel global time_second. > > > > Can we make a page in kernel address space which is readable my user > code? put the variable in the page, I know read an integer is atomic-op, > needn't lock, so syscall is not needed. Don't whink it is importent for 1s intervalls, but atomic != coherent. -- B.Walter BWCT http://www.bwct.de bernd@bwct.de info@bwct.de
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