linux-kernel - Re: [PATCH] scheduler: fix x86 regression in native_sched

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Message-ID: <20071208154122.GE30270@elte.hu>
Date:	Sat, 8 Dec 2007 16:41:22 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Michael Buesch <mb@...sch.de>
Cc:	Mark Lord <lkml@....ca>, Guillaume Chazarain <guichaz@...oo.fr>,
	stefano.brivio@...imi.it, Nick Piggin <nickpiggin@...oo.com.au>,
	Robert Love <rml@...h9.net>, linux-kernel@...r.kernel.org,
	Dave Jones <davej@...hat.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Len Brown <lenb@...nel.org>
Subject: Re: [PATCH] scheduler: fix x86 regression in native_sched_clock


* Michael Buesch <mb@...sch.de> wrote:

> > i cannot see how. You can verify msleep by running something like this:
> > 
> >   while :; do time usleep 111000; done
> > 
> > you should see a steady stream of:
> > 
> >  real    0m0.113s
> >  real    0m0.113s
> >  real    0m0.113s
> > 
> > (on an idle system). If it fluctuates, with occasional longer delays, 
> > there's some timer problem present.
> 
> Does the sleeping and timing use different time references?

yes. But the real paranoid can do this from another box:

  while :; do time ssh testbox usleep 111000; done

	Ingo
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