From: a.p.zijlstra@chello.nl (Peter Zijlstra)
To: linux-arm-kernel@lists.infradead.org
Subject: sched: ARM: arch_scale_freq_power
Date: Tue, 11 Oct 2011 18:21:15 +0200 [thread overview]
Message-ID: <1318350075.14615.9.camel@twins> (raw)
In-Reply-To: <CAKfTPtDgKcTucAR-YW27boAeUu1Ur6Txw6hLm3B48jw+sgEUOw@mail.gmail.com>
On Tue, 2011-10-11 at 18:03 +0200, Vincent Guittot wrote:
> > How do you know the task is 'small' ?
> >
>
> I want to use cpufreq to be notified that we have a large/small cpu
> load. If we have several tasks but the cpu uses the lowest frequency,
> it "should" mean that we have small tasks that are running (less than
> 20ms*95% of added duration) and we could gather them on one cpu (by
> increasing the cpu_power on a dual core).
>
> > For that you would need to track a time-weighted effective load average
> > of the task and we don't have that.
> >
>
> yes, that's why I use cpufreq until better option, like a
> time-weighted load average, is available
Egads... so basically you're (ab)using the ondemand cpufreq stats to get
a guestimate of the time-weighted load of the cpu, and then (ab)use the
scheduler cpufreq hook to pump its capacity numbers.
No cookies for you.
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Amit Kucheria <amit.kucheria@linaro.org>,
linux-kernel@vger.kernel.org,
LAK <linux-arm-kernel@lists.infradead.org>,
linaro-dev@lists.linaro.org,
Srivatsa Vaddagiri <vatsa@in.ibm.com>,
Venkatesh Pallipadi <venki@google.com>,
Suresh Siddha <suresh.b.siddha@intel.com>,
Ingo Molnar <mingo@elte.hu>, Paul Turner <pjt@google.com>
Subject: Re: sched: ARM: arch_scale_freq_power
Date: Tue, 11 Oct 2011 18:21:15 +0200 [thread overview]
Message-ID: <1318350075.14615.9.camel@twins> (raw)
In-Reply-To: <CAKfTPtDgKcTucAR-YW27boAeUu1Ur6Txw6hLm3B48jw+sgEUOw@mail.gmail.com>
On Tue, 2011-10-11 at 18:03 +0200, Vincent Guittot wrote:
> > How do you know the task is 'small' ?
> >
>
> I want to use cpufreq to be notified that we have a large/small cpu
> load. If we have several tasks but the cpu uses the lowest frequency,
> it "should" mean that we have small tasks that are running (less than
> 20ms*95% of added duration) and we could gather them on one cpu (by
> increasing the cpu_power on a dual core).
>
> > For that you would need to track a time-weighted effective load average
> > of the task and we don't have that.
> >
>
> yes, that's why I use cpufreq until better option, like a
> time-weighted load average, is available
Egads... so basically you're (ab)using the ondemand cpufreq stats to get
a guestimate of the time-weighted load of the cpu, and then (ab)use the
scheduler cpufreq hook to pump its capacity numbers.
No cookies for you.
next prev parent reply other threads:[~2011-10-11 16:21 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-06 11:36 sched: ARM: arch_scale_freq_power Vincent Guittot
2011-10-06 11:36 ` Vincent Guittot
2011-10-11 7:16 ` Amit Kucheria
2011-10-11 7:16 ` Amit Kucheria
2011-10-11 7:57 ` Peter Zijlstra
2011-10-11 7:57 ` Peter Zijlstra
2011-10-11 8:51 ` Vincent Guittot
2011-10-11 8:51 ` Vincent Guittot
2011-10-11 9:13 ` Peter Zijlstra
2011-10-11 9:13 ` Peter Zijlstra
2011-10-11 9:38 ` Amit Kucheria
2011-10-11 9:38 ` Amit Kucheria
2011-10-11 10:03 ` Peter Zijlstra
2011-10-11 10:03 ` Peter Zijlstra
2011-10-11 9:40 ` Vincent Guittot
2011-10-11 9:40 ` Vincent Guittot
2011-10-11 10:27 ` Peter Zijlstra
2011-10-11 10:27 ` Peter Zijlstra
2011-10-11 16:03 ` Vincent Guittot
2011-10-11 16:03 ` Vincent Guittot
2011-10-11 16:21 ` Peter Zijlstra [this message]
2011-10-11 16:21 ` Peter Zijlstra
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