linux-kernel - Re: [PATCH 01/19] freezer: don't get over-anxious while waiting

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Date:	Fri, 02 Oct 2009 19:56:33 +0900
From:	Tejun Heo <tj@...nel.org>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
CC:	Pavel Machek <pavel@....cz>, jeff@...zik.org, mingo@...e.hu,
	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
	jens.axboe@...cle.com, rusty@...tcorp.com.au,
	cl@...ux-foundation.org, dhowells@...hat.com,
	arjan@...ux.intel.com,
	pm list <linux-pm@...ts.linux-foundation.org>,
	Oren Laadan <orenl@...rato.com>
Subject: Re: [PATCH 01/19] freezer: don't get over-anxious while waiting

Hello, Pavel, Rafael.

Rafael J. Wysocki wrote:
> On Thursday 01 October 2009, Pavel Machek wrote:
>>> Freezing isn't exactly the most latency sensitive operation and
>>> there's no reason to burn cpu cycles and power waiting for it to
>>> complete.  msleep(10) instead of yield().  This should improve
>>> reliability of emergency hibernation.
>> i don't see how it improves reliability, but its probably ok.

It's about battery.  When emergency hibernation kicks in and something
is taking a while to freeze (usually nfs does this for me) burning
power waiting for it to finish is a pretty bad idea.

>> Well... for hibernation anyway. I can imagine cgroup users where
>> freeze is so fast that this matters. rjw cc-ed.		pavel
> 
> Thanks.  I'd like to hear from the cgroup freezer people about that.

Oh... didn't know that.  10ms sleeps really matter there?

-- 
tejun
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