linux-kernel - Re: [PATCH] trace power_frequency events on the correct cpu (for Intel x86 CPUs)

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Date:	Sat, 20 Mar 2010 22:37:56 +0100
From:	Thomas Renninger <trenn@...e.de>
To:	Robert Schöne <robert.schoene@...dresden.de>
Cc:	Arjan van de Ven <arjan@...ux.intel.com>,
	Dave Jones <davej@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"linux-kernel" <linux-kernel@...r.kernel.org>,
	cpufreq <cpufreq@...r.kernel.org>, x86@...nel.org
Subject: Re: [PATCH] trace power_frequency events on the correct cpu  (for Intel x86 CPUs)

> This wrapper would make things easier of course, since one might add the
> same line for every driver
...
It's simply broken and can't be fixed without chaninging the whole concept.
power_frequency_events() must not only pass the cpu, but a cpumask also for 
acpi-cpufreq.
If you look at SW_ANY SW_ALL (or similar, I can't look at code right now) 
parts, acpi-cpufreq can change the frequency for several cores with one MSR 
write.
AFAIK this is for example the recommended way for Dunnington (6 cores).
So the collected data can be totally wrong.
Better remove this before others also start to use it.
It also seem to be (hopefully) a minor feature for timechart, so this should 
not hurt that much (yet).

     Thomas
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