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Date: Fri, 28 Oct 2005 14:58:28 +0200
From: Bernd Walter <ticso@cicely12.cicely.de>
To: David Xu <davidxu@freebsd.org>
Message-ID: <20051028125828.GE66456@cicely12.cicely.de>
References: <31129.1130495688@critter.freebsd.dk> <436200BE.70604@freebsd.org>
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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
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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