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Date: Fri, 27 Feb 2009 21:40:53 +0100
From: Pavel Machek <pavel@ucw.cz>
To: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Arve Hj?nnev?g <arve@android.com>, Alan Stern <stern@rowland.harvard.edu>,
       "Woodruff, Richard" <r-woodruff2@ti.com>,
       Arjan van de Ven <arjan@infradead.org>,
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       Igor Stoppa <igor.stoppa@nokia.com>,
       Brian Swetland <swetland@google.com>, Len Brown <lenb@kernel.org>
Subject: Re: [RFD] Automatic suspend
Message-ID: <20090227204053.GB1387@ucw.cz>
References: <200902192215.18365.rjw@sisk.pl> <200902210057.27781.rjw@sisk.pl> <20090227100941.GE4582@elf.ucw.cz> <200902271522.41915.rjw@sisk.pl>
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On Fri 2009-02-27 15:22:39, Rafael J. Wysocki wrote:
> On Friday 27 February 2009, Pavel Machek wrote:
> > Hi!
> > 
> > > > > Then, the decision making logic will be able to use /sys/power/sleep whenever
> > > > > it wishes to and the kernel will be able to refuse to suspend if it's not
> > > > > desirable at the moment.
> > > > >
> > > > > It seems to be flexible enough to me.
> > > > 
> > > > This seems flexible enough to avoid race conditions, but it forces the
> > > > user space power manager to poll when the kernel refuse suspend.
> > > 
> > > And if the kernel is supposed to start automatic suspend, it has to monitor
> > > all of the wakelocks.  IMO, it's better to allow the power manager to poll the
> > > kernel if it refuses to suspend.
> > 
> > polling is evil -- it keeps CPU wake up => wastes power.
> > 
> > Wakelocks done right are single atomic_t... and if you set it to 0,
> > you just unblock "sleeper" thread or something. Zero polling and very
> > simple...
> 
> Except that you have to check all of the wakelocks periodically in a loop =>
> polling.  So?

No. I want to have single atomic_t for all the wakelocks... at least
in non-debug version. Debug version will be slower. I believe you
originally suggested that.
								Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
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