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Date: Fri, 28 Oct 2005 17:48:19 +0800
From: Jiawei Ye <leafy7382@gmail.com>
To: Poul-Henning Kamp <phk@phk.freebsd.dk>
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References: <20051028091016.GC3596@garage.freebsd.pl>
	<30513.1130492612@critter.freebsd.dk>
Cc: Mark Kirkwood <markir@paradise.net.nz>,
	Pawel Jakub Dawidek <pjd@freebsd.org>, David Xu <davidxu@freebsd.org>,
	"Yuriy N. Shkandybin" <jura@networks.ru>, current@freebsd.org
Subject: Re: Timers and timing, was: MySQL Performance 6.0rc1
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On 10/28/05, Poul-Henning Kamp <phk@phk.freebsd.dk> wrote:
>
> By default the timecounter with the highest score is selected (but
> negative scores are never selected automatically).
>
> You can override this with
>         sysctl kern.timecounter.hardware=3Dsomething
> where something is one of the timecounters listed in kern.timecounter.cho=
ice
>
> --
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
This is what I get on a UP P4-1.8 -current system. No debugging enabled ker=
nel.

root@chihiro:/home/leafy/tmp# sysctl kern.timecounter.hardware=3DTSC
kern.timecounter.hardware: ACPI-fast -> TSC
root@chihiro:/home/leafy/tmp# ./a.out
       null function: 0.00794
            getpid(): 0.94267
              time(): 1.26512
      gettimeofday(): 1.25332
root@chihiro:/home/leafy/tmp# sysctl kern.timecounter.hardware=3DACPI-fast
kern.timecounter.hardware: TSC -> ACPI-fast
root@chihiro:/home/leafy/tmp# ./a.out
       null function: 0.00796
            getpid(): 0.94788
              time(): 2.31868
      gettimeofday(): 2.29598
root@chihiro:/home/leafy/tmp# sysctl kern.timecounter.hardware=3Di8254
kern.timecounter.hardware: ACPI-fast -> i8254
root@chihiro:/home/leafy/tmp# ./a.out
       null function: 0.00812
            getpid(): 0.96921
              time(): 5.01022
      gettimeofday(): 5.01292

--
"Without the userland, the kernel is useless."
               --inspired by The Tao of Programming