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

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Message-ID: <1269414437.3355.6.camel@localhost>
Date:	Wed, 24 Mar 2010 08:07:17 +0100
From:	Robert Schöne <robert.schoene@...dresden.de>
To:	Arjan van de Ven <arjan@...ux.intel.com>
Cc:	Thomas Renninger <trenn@...e.de>, 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)

Am Dienstag, den 23.03.2010, 09:58 -0700 schrieb Arjan van de Ven:
> On 3/23/2010 9:57, Thomas Renninger wrote:
> > On Tuesday 23 March 2010 17:28:36 Robert SchÃ¶ne wrote:
> >> Am Montag, den 22.03.2010, 06:57 -0700 schrieb Arjan van de Ven:
> >>> On 3/22/2010 0:04, Robert SchÃ¶ne wrote:
> >>>> Am Sonntag, den 21.03.2010, 17:42 -0700 schrieb Arjan van de Ven:
> >>>>> On 3/20/2010 14:37, Thomas Renninger wrote:
> >>>>>
> >>>>>> It also seem to be (hopefully) a minor feature for timechart, so this should
> >>>>>> not hurt that much (yet).
> >>>>>
> >>>>> It's actually a major feature for timechart, and one of the key things I and a bunch of others
> >>>>> inside Intel use timechart for.
> >>>>>
> >>>> It's a major feature for us too.
> >>>> I suppose, the cpufreq_notify_transition calls are correct (meaning
> >>>> being called for all related cpus) for every driver. So there's still
> >>>> the option to include it in the POST_CHANGE section of this function.
> >>>> Could this be okay for the both of you?
> >>>
> >>> post change would work... that gets frequency afaik..
> >> Are you ok with this too, Thomas?
> > You mean hooking it into cpufreq_stat_notifier_trans() in
> > drivers/cpufreq/cpufreq_stats.c?
> 
> no
> 
> 
> hooking into the post frequency change callback that gets done..
> which is guaranteed to be on the right cpu afaics.
> 
I don't see where this would be guaranteed. So I'd be fine with
a) adding it to
cpufreq.c/cpufreq_notify_transition/cpufreq_notify_transition

b) adding an item to the cpufreq_transition_notifier_list

c) adding it to cpufreq_stats.c/cpufreq_stat_notifier_trans

which would imply the usage of smp_call_function_single(...)


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