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Re: [PATCH] Use uname not sysctl to get the kernel revision

From: "H. Peter Anvin" <hpa at zytor dot com>
To: Arjan van de Ven <arjan at infradead dot org>
Cc: "Eric W. Biederman" <ebiederm at xmission dot com>, Jakub Jelinek <jakub at redhat dot com>, Ulrich Drepper <drepper at redhat dot com>, Roland McGrath <roland at redhat dot com>, "Randy.Dunlap" <rdunlap at xenotime dot net>, akpm at osdl dot org, linux-kernel at vger dot kernel dot org, libc-alpha at sourceware dot org
Date: Wed, 12 Jul 2006 15:02:57 -0700
Subject: Re: [PATCH] Use uname not sysctl to get the kernel revision
References: <20060712184412.2BD57180061@magilla.sf.frob.com> <44B54EA4.5060506@redhat.com> <20060712195349.GW3823@sunsite.mff.cuni.cz> <44B556E5.5000702@zytor.com> <m1k66i8ql5.fsf@ebiederm.dsl.xmission.com> <1152739766.3217.83.camel@laptopd505.fenrus.org> <m1bqru8p36.fsf@ebiederm.dsl.xmission.com> <1152741665.3217.85.camel@laptopd505.fenrus.org>

Arjan van de Ven wrote:

It is a short busy wait before falling asleep.  I assume you mean
busy wait is a loss even on SMP?


eh yeah I forgot to think for a second. But yes even for SMP busy wait
is pretty bad power wise nowadays.. at least if you wait more than a few
hundred cycles. (and if you wait less... then it's almost unlikely that
it'll be useful as well)

It depends greatly; if a lock is likely to get released by the user after a few memory accesses, spinning is likely to be a win.

-hpa

Follow-Ups:
- Re: [PATCH] Use uname not sysctl to get the kernel revision
  - From: Eric W. Biederman

References:
- Re: [PATCH] Use uname not sysctl to get the kernel revision
  - From: Roland McGrath
- Re: [PATCH] Use uname not sysctl to get the kernel revision
  - From: Ulrich Drepper
- Re: [PATCH] Use uname not sysctl to get the kernel revision
  - From: Jakub Jelinek
- Re: [PATCH] Use uname not sysctl to get the kernel revision
  - From: H. Peter Anvin
- Re: [PATCH] Use uname not sysctl to get the kernel revision
  - From: Eric W. Biederman
- Re: [PATCH] Use uname not sysctl to get the kernel revision
  - From: Arjan van de Ven
- Re: [PATCH] Use uname not sysctl to get the kernel revision
  - From: Eric W. Biederman
- Re: [PATCH] Use uname not sysctl to get the kernel revision
  - From: Arjan van de Ven

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