linux-kernel - Re: [BISECTED] Lots of "rescheduling IPIs" in powertop

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Message-ID: <87prrp6ri9.fsf@basil.nowhere.org>
Date:	Wed, 14 May 2008 13:42:54 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Andreas Herrmann <andreas.herrmann3@....com>
Cc:	Ingo Molnar <mingo@...e.hu>,
	Vegard Nossum <vegard.nossum@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	S.Çağlar Onur <caglar@...dus.org.tr>,
	Valdis.Kletnieks@...edu, Matt Mackall <mpm@...enic.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [BISECTED] Lots of "rescheduling IPIs" in powertop

Andreas Herrmann <andreas.herrmann3@....com> writes:
>
> It depends on the CPU. For AMD CPUs that support MWAIT this is wrong.
> Family 0x10 and 0x11 CPUs will enter C1 on HLT. Powersavings then
                                ^ not

> It might be best to switch off the mwait flag for these AMD CPU
> families like it was introduced with commit
> f039b754714a422959027cb18bb33760eb8153f0 (x86: Don't use MWAIT on AMD
> Family 10)

Then you have to special case everything again. We still need to 
work out if the P4 is even correct here or not, but if it's not
i would rather quirk the cpuid reporting on it.

-Andi
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