From: Pierre Ossman <drzeus-list@drzeus.cx>
To: Len Brown <lenb@kernel.org>
Cc: linux-pm@lists.linux-foundation.org, Pavel Machek <pavel@ucw.cz>,
LKML <linux-kernel@vger.kernel.org>,
Adam Belay <abelay@novell.com>, Andi Kleen <andi@firstfloor.org>,
Lee Revell <rlrevell@joe-job.com>
Subject: Re: [linux-pm] [PATCH] cpuidle: avoid singing capacitors
Date: Thu, 13 Mar 2008 17:34:37 +0100 [thread overview]
Message-ID: <20080313173437.5f00f70e@mjolnir.drzeus.cx> (raw)
In-Reply-To: <200803121511.17389.lenb@kernel.org>
On Wed, 12 Mar 2008 15:11:17 -0400
Len Brown <lenb@kernel.org> wrote:
> > I guess the only way to find out is to disassemble the DSDT. Exposing myself to such concentrations of ACPI is not an appealing project. :/
>
> the latest cpuidle code actually publishes the details of the C-states being used.
>
> $ pwd
> /sys/devices/system/cpu/cpu0/cpuidle/state3
> $ grep . *
> desc:ACPI FFH INTEL MWAIT 0x20
> latency:17
> name:C3
> power:250
> time:1862590932
> usage:9028970
>
> You'll see "desc" change if ACPI pulls a _CST change on you.
>
It does not. But my C3 desc looks like this:
state3/desc:ACPI FFH INTEL MWAIT 0x50
What's the meaning of the last number?
I also have different latency and power:
state3/latency:162
state3/power:100
> > Disabling the second core makes the noise go away. This might be a subset of 1., as I've been told that a stopped core enters C1.
>
> if you disable it at run-time, Linux puts it in C1.
> If you never boot it in the first place (eg. maxcpusp=1), the BIOS leaves it in the deepest available C-sate.
>
Ah. Didn't know that. I've confirmed this as the noise is there when booting with maxcpus.
> >
> > So for now, the only viable workaround is processor.max_cstate....
>
> yup, that's why we put it in. Is it insufficient?
>
For some value of insufficient. It is sub-optimal. I'm hoping there is a way to enter C3 in a pattern that avoids the noise and still gives a reduced power usage.
Rgds
--
-- Pierre Ossman
Linux kernel, MMC maintainer http://www.kernel.org
PulseAudio, core developer http://pulseaudio.org
rdesktop, core developer http://www.rdesktop.org
next prev parent reply other threads:[~2008-03-13 16:35 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-02-29 18:38 [RFC][PATCH] cpuidle: avoid singing capacitors Pierre Ossman
2008-02-29 21:44 ` Lennart Sorensen
2008-03-01 12:31 ` Pierre Ossman
2008-03-01 13:40 ` Pierre Ossman
2008-03-02 2:27 ` Lee Revell
2008-03-02 14:17 ` Pierre Ossman
2008-03-03 12:36 ` Andi Kleen
2008-03-03 20:18 ` [PATCH] " Pierre Ossman
2008-03-03 20:46 ` Pavel Machek
2008-03-03 21:03 ` Pierre Ossman
2008-03-03 21:08 ` Pavel Machek
2008-03-03 21:14 ` Pallipadi, Venkatesh
2008-03-03 21:17 ` Pierre Ossman
2008-03-03 22:04 ` Pallipadi, Venkatesh
2008-03-03 23:05 ` [linux-pm] " Alan Stern
2008-03-03 23:10 ` Andi Kleen
2008-03-04 4:00 ` Dave Jones
2008-03-04 6:14 ` Pierre Ossman
2008-03-04 17:19 ` Pierre Ossman
2008-03-04 17:29 ` Andi Kleen
2008-03-04 17:30 ` Pierre Ossman
2008-03-04 17:43 ` Andi Kleen
2008-03-04 18:04 ` Pierre Ossman
2008-03-04 18:34 ` Andi Kleen
2008-03-05 6:04 ` Pierre Ossman
2008-03-05 15:48 ` Andi Kleen
2008-03-05 16:53 ` Pierre Ossman
2008-03-05 17:32 ` Andi Kleen
2008-03-04 19:01 ` Pallipadi, Venkatesh
2008-03-05 6:02 ` Pierre Ossman
2008-03-05 8:40 ` Pierre Ossman
2008-03-05 9:03 ` Pavel Machek
2008-03-05 13:42 ` Pierre Ossman
2008-03-05 13:47 ` Pavel Machek
2008-03-05 13:52 ` Pierre Ossman
2008-03-06 8:27 ` Pierre Ossman
2008-03-09 14:16 ` Pierre Ossman
2008-03-09 18:19 ` Rafael J. Wysocki
2008-03-09 18:50 ` Alan Stern
2008-03-09 19:30 ` Henrique de Moraes Holschuh
2008-03-09 20:14 ` Pierre Ossman
2008-03-09 20:41 ` Henrique de Moraes Holschuh
2008-03-09 20:54 ` Henrique de Moraes Holschuh
2008-03-10 10:00 ` Pavel Machek
2008-03-10 12:49 ` Pierre Ossman
2008-03-10 13:04 ` Andi Kleen
2008-03-10 13:29 ` Pierre Ossman
2008-03-12 19:11 ` Len Brown
2008-03-13 8:10 ` Pavel Machek
2008-03-13 10:42 ` Andi Kleen
2008-03-14 4:13 ` Len Brown
2008-03-13 16:34 ` Pierre Ossman [this message]
2008-03-13 16:47 ` Pallipadi, Venkatesh
2008-03-13 17:44 ` Pierre Ossman
2008-03-13 17:49 ` Pierre Ossman
2008-03-14 19:40 ` Pierre Ossman
2008-03-14 21:15 ` Pallipadi, Venkatesh
2008-03-15 0:41 ` Pierre Ossman
2008-03-11 7:51 ` Pierre Ossman
2008-03-11 10:48 ` Andi Kleen
2008-03-11 15:20 ` Pierre Ossman
2008-03-11 17:31 ` Pierre Ossman
2008-03-12 19:17 ` Len Brown
2008-03-12 20:31 ` Len Brown
2008-03-04 9:40 ` Andi Kleen
2008-03-03 23:09 ` Andi Kleen
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