LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
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

  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] " 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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20080313173437.5f00f70e@mjolnir.drzeus.cx \
    --to=drzeus-list@drzeus.cx \
    --cc=abelay@novell.com \
    --cc=andi@firstfloor.org \
    --cc=lenb@kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pm@lists.linux-foundation.org \
    --cc=pavel@ucw.cz \
    --cc=rlrevell@joe-job.com \
    --subject='Re: [linux-pm] [PATCH] cpuidle: avoid singing capacitors' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).