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

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Date:	Fri, 12 Mar 2010 16:41:46 +0100
From:	Robert Schöne <robert.schoene@...dresden.de>
To:	Arjan van de Ven <arjan@...ux.intel.com>
Cc:	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 Freitag, den 12.03.2010, 06:52 -0800 schrieb Arjan van de Ven:
> On 3/12/2010 5:17, Robert Schöne wrote:
> > This patch fixes the following behaviour:
> > Currently, the power_frequency event is reported for the cpu (core) which initiated the frequency change.
> > It should be reported for the cpu that actually changes its frequency.
> >
> > Example: when using
> >   taskset -c 0 echo<new_frequency>  >  /sys/devices/system/cpu/cpu1/cpufreq/scaling_setspeed
> > cpu 0 is traced, instead of cpu 1
> >
> > Signed of by Robert Schoene<robert.schoene@...dresden.de>
> >
> >
> > diff --git a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c b/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
> > index 1b1920f..0a47f10 100644
> > --- a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
> > +++ b/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
> > @@ -174,6 +174,7 @@ static void do_drv_write(void *_cmd)
> >
> >          switch (cmd->type) {
> >          case SYSTEM_INTEL_MSR_CAPABLE:
> > +               trace_power_frequency(POWER_PSTATE, cmd->val);
> >                  rdmsr(cmd->addr.msr.reg, lo, hi);
> >                  lo = (lo&  ~INTEL_MSR_RANGE) | (cmd->val&  INTEL_MSR_RANGE);
> >                  wrmsr(cmd->addr.msr.reg, lo, hi);
> > @@ -363,7 +364,6 @@ static int acpi_cpufreq_target(struct cpufreq_policy *policy,
> >                  }
> >          }
> >
> > -       trace_power_frequency(POWER_PSTATE, data->freq_table[next_state].frequency);
> >
> >          switch (data->cpu_feature) {
> >          case SYSTEM_INTEL_MSR_CAPABLE:
> >
> >
> 
> are you sure this is right?
> it's moving something from outside a switch statement to inside only one prong of a switch statement...

I'm pretty sure, since I'm moving it from function acpi_cpufreq_target(...) to do_drv_write(...)

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-- 
Robert Schoene
Technische Universitaet Dresden
Zentrum fuer Informationsdienste und Hochleistungsrechnen
01062 Dresden

Tel.: (0351) 463-42483, Fax: (0351) 463-37773
E-Mail: Robert.Schoene@...dresden.de

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