linux-kernel - Re: [BUG] cpufreq: constant cpu

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Message-ID: <20080825175712.GA10848@elte.hu>
Date:	Mon, 25 Aug 2008 19:57:12 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Dave Jones <davej@...emonkey.org.uk>,
	Peter Zijlstra <peterz@...radead.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	cpufreq@...r.kernel.org, Alok Kataria <akataria@...are.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [BUG] cpufreq: constant cpu_khz


* Dave Jones <davej@...emonkey.org.uk> wrote:

>  > hm, that too is due to the tsc.c unification - Alok Cc:-ed. Applied 
>  > your fix to x86/urgent.
> 
> ACKed-by: Dave Jones <davej@...hat.com>
> 
> Good catch Peter.  I'm puzzled how that bug was latent on 64bit for so 
> long with no-one realising though.

i think it's the combination of these two factors:

 - bootup frequently is typically full-speed, so we calibrate things 
   right

 - cpufreq events are relatively slow-scale - and when they trigger the 
   system is definitely not under load. So how precisely the scheduler 
   functions isnt all that important in such scenarios - there's tons of
   CPU power available.

but it's indeed nice to have this fixed, and i just pushed the fix to 
Linus.

	Ingo
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