From: Arjan van de Ven <arjan@infradead.org>
To: Pavel Machek <pavel@ucw.cz>
Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
mingo@elte.hu, peterz@infradead.org, tglx@linutronix.de,
davej@redhat.com, cpufreq@vger.kernel.org
Subject: Re: [PATCH 7/7] ondemand: Solve the big performance issue with ondemand during disk IO
Date: Fri, 23 Apr 2010 09:06:48 -0700 [thread overview]
Message-ID: <20100423090648.17399f47@infradead.org> (raw)
In-Reply-To: <20100423083828.GA1573@ucw.cz>
On Fri, 23 Apr 2010 10:38:28 +0200
Pavel Machek <pavel@ucw.cz> wrote:
> On Fri 2010-04-23 06:52:48, Arjan van de Ven wrote:
> > On Fri, 23 Apr 2010 07:24:39 +0200
> > Pavel Machek <pavel@ucw.cz> wrote:
> >
> > >
> > > Well, and now, if you do something like cat /dev/<your usb1.1
> > > hdd> > /dev/null, you'll keep cpu on max frequency. Not a problem
> > > hdd> > for new
> > > core i7, but probably big deal for athlon 64.
> >
> > do you have facts not speculation for this? Does the athlon 64
> > really
>
> You want the patch applied, you should be able to justify it.
You make a claim... all I am asking if you are doing just random guess
or basing this on facts.
The machines I have access to don't show any impact during actual idle,
because they stop clocks and generally even lower the voltage.
You make a claim that a certain machine does not do either... all I'm
asking if that claim is based on data or on speculation.
>
> > keep its voltage high during idle? That would surprise me greatly...
> > (and if it does, does it matter? the clock is stopped anyway there)
>
> Yes, I believe it keeps voltage up, and as a leakage is big part of
> power consumption there, stopped clocks will not help much.
again do you have actual data?
> I believe you are developing on wrong machine. Seems like core i7 just
> wants max frequency, all the time. Older designs were not like that.
>
> Do you have early intel speedstep machine near you?
oh I use many different machines. the intel machines at least stop the
clocks, and for a really long time also lower the frequency in idle.
(especially during deeper C states, but even during C1)
>
> > the only place where my patch makes a real difference is when the
> > cpu is idle due to blocking IO! So do you have data that the athlon
> > 64 gets too hot if you select a high frequency during an idle
> > period, where the clock is already stopped?
>
> iirc even idle power consumption was much higher when on max
> voltage... I'll get some numbers from my old notes; I no longer have
> the hw.
make sure it's data based on tickless... without tickless we were never
really idle ;-(
--
Arjan van de Ven Intel Open Source Technology Centre
For development, discussion and tips for power savings,
visit http://www.lesswatts.org
next prev parent reply other threads:[~2010-04-23 16:04 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-18 18:59 [PATCH 0/7] Fix performance issue with ondemand governor Arjan van de Ven
2010-04-18 19:00 ` [PATCH 1/7] sched: add a comment to get_cpu_idle_time_us() Arjan van de Ven
2010-04-26 19:25 ` Rik van Riel
2010-04-18 19:01 ` [PATCH 2/7] sched: introduce a function to update the idle statistics Arjan van de Ven
2010-04-26 20:11 ` Rik van Riel
2010-04-18 19:01 ` [PATCH 3/7] sched: update the idle statistics in get_cpu_idle_time_us() Arjan van de Ven
2010-04-26 20:36 ` Rik van Riel
2010-04-18 19:02 ` [PATCH 4/7] sched: fold updating of the last update time into update_ts_time_stats() Arjan van de Ven
2010-04-26 20:58 ` Rik van Riel
2010-04-18 19:02 ` [PATCH 5/7] sched: eliminate the ts->idle_lastupdate field Arjan van de Ven
2010-04-26 21:00 ` Rik van Riel
2010-04-18 19:03 ` [PATCH 6/7] sched: introduce get_cpu_iowait_time_us() Arjan van de Ven
2010-04-26 21:05 ` Rik van Riel
2010-04-18 19:03 ` [PATCH 7/7] ondemand: Solve the big performance issue with ondemand during disk IO Arjan van de Ven
2010-04-19 8:29 ` Éric Piel
2010-04-19 13:43 ` Arjan van de Ven
2010-04-19 14:30 ` Éric Piel
2010-04-19 14:47 ` Arjan van de Ven
2010-04-20 9:24 ` Thomas Renninger
2010-04-27 0:29 ` Mike Chan
2010-04-27 13:01 ` Pavel Machek
2010-04-27 18:10 ` Mike Chan
2010-04-19 9:09 ` Tvrtko Ursulin
2010-04-19 13:46 ` Arjan van de Ven
2010-04-19 15:29 ` Tvrtko Ursulin
2010-04-20 0:47 ` Arjan van de Ven
2010-04-20 9:10 ` Tvrtko Ursulin
2010-04-20 11:02 ` Arjan van de Ven
2010-04-28 8:57 ` Tvrtko Ursulin
2010-04-23 5:26 ` Pavel Machek
2010-04-20 9:29 ` Thomas Renninger
2010-04-20 11:07 ` Arjan van de Ven
2010-04-23 5:24 ` Pavel Machek
2010-04-23 5:38 ` Willy Tarreau
2010-04-23 8:50 ` Thomas Renninger
2010-04-23 16:08 ` Arjan van de Ven
2010-04-27 11:39 ` Thomas Renninger
2010-05-04 3:48 ` [PATCH 8/7] cpufreq: make the iowait-is-busy-time a sysfs tunable Arjan van de Ven
2010-05-04 4:16 ` Willy Tarreau
2010-05-04 5:43 ` Pavel Machek
2010-05-04 13:51 ` Rik van Riel
2010-04-23 14:10 ` [PATCH 7/7] ondemand: Solve the big performance issue with ondemand during disk IO Arjan van de Ven
2010-04-23 15:35 ` Willy Tarreau
2010-04-23 13:52 ` Arjan van de Ven
2010-04-23 8:38 ` Pavel Machek
2010-04-23 16:06 ` Arjan van de Ven [this message]
2010-04-24 4:56 ` Pavel Machek
2010-05-01 23:29 ` Arjan van de Ven
2010-04-26 21:30 ` Rik van Riel
2010-04-26 21:41 ` [PATCH 0/7] Fix performance issue with ondemand governor Dave Jones
2010-04-26 21:45 ` Dominik Brodowski
2010-04-26 21:59 ` Rik van Riel
2010-04-26 22:05 ` Dominik Brodowski
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