Date: Tue, 18 Oct 2005 15:47:36 +0200 From: "Poul-Henning Kamp" <phk@phk.freebsd.dk> To: Andrew Gallatin <gallatin@cs.duke.edu> Cc: cvs-src@FreeBSD.org, src-committers@FreeBSD.org, David Xu <davidxu@FreeBSD.org>, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/amd64/amd64 cpu_switch.S machdep.c Message-ID: <68671.1129643256@critter.freebsd.dk> In-Reply-To: Your message of "Tue, 18 Oct 2005 09:44:02 EDT." <20051018094402.A29138@grasshopper.cs.duke.edu>
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In message <20051018094402.A29138@grasshopper.cs.duke.edu>, Andrew Gallatin wri tes: >It is a shame we can't find a way to use the TSC as a timecounter on >SMP systems. It seems that about 40% of the context switch time is >spent just waiting for the PIO read of the ACPI-fast or i8254 to >return. No, the shame is that the scheduler tries to partition time rather than cpu cycles because that approximation got goldplated in some random standard years back. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.
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