LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Pierre Ossman <drzeus-list@drzeus.cx>
To: Andi Kleen <andi@firstfloor.org>
Cc: Andi Kleen <andi@firstfloor.org>,
	"Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>,
	Dave Jones <davej@codemonkey.org.uk>,
	Alan Stern <stern@rowland.harvard.edu>,
	LKML <linux-kernel@vger.kernel.org>,
	Adam Belay <abelay@novell.com>, Lee Revell <rlrevell@joe-job.com>,
	linux-pm@lists.linux-foundation.org, Pavel Machek <pavel@ucw.cz>
Subject: Re: [linux-pm] [PATCH] cpuidle: avoid singing capacitors
Date: Wed, 5 Mar 2008 17:53:39 +0100	[thread overview]
Message-ID: <20080305175339.2059226b@mjolnir.drzeus.cx> (raw)
In-Reply-To: <20080305154856.GC553@one.firstfloor.org>

On Wed, 5 Mar 2008 16:48:56 +0100
Andi Kleen <andi@firstfloor.org> wrote:

> 
> Start: You discovered at some point where you currently have code a variable 
> is not updated yet.
> Fact: You have some new code that runs before that point
> Information: The variable is updated later eventually in the idle exit path.
> Fact II: You require the variable to be updated in your new code

For some value of "require". The code will do what it's supposed to do anyway, just in a sub-optimal way (it will avoid a deep sleep even though it didn't need to).

> Possible solutions: 
> (1) you move your new code in a point of the idle exit path after the variable 
> is updated 

But I don't use jiffies in the idle exit path, only the entry path.

> (2) you move the code that updates the variable earlier before your code

Which basically leaves this option. I.e. guarantee that jiffies are updated between one cpuidle reflect and the subsequent select.

> Solution: I described the first variant which is likely easier.
> How: I told you where it is updated, so that shouldn't be too difficult. 
> Action: Implement solution (1) or (2) 
> Action: Test if it works
> Check: If test succeeded exit 
> Otherwise: Restart at Start
> 

Now you're just being a smart-ass. :)

-- 
     -- Pierre Ossman

  Linux kernel, MMC maintainer        http://www.kernel.org
  PulseAudio, core developer          http://pulseaudio.org
  rdesktop, core developer          http://www.rdesktop.org

  reply	other threads:[~2008-03-05 16:55 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 [this message]
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
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=20080305175339.2059226b@mjolnir.drzeus.cx \
    --to=drzeus-list@drzeus.cx \
    --cc=abelay@novell.com \
    --cc=andi@firstfloor.org \
    --cc=davej@codemonkey.org.uk \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pm@lists.linux-foundation.org \
    --cc=pavel@ucw.cz \
    --cc=rlrevell@joe-job.com \
    --cc=stern@rowland.harvard.edu \
    --cc=venkatesh.pallipadi@intel.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).