From mboxrd@z Thu Jan  1 00:00:00 1970
From: Pavel Machek <pavel@ucw.cz>
Subject: Re: [RFC][PATCH -mm 2/2] Freezer: Use wait queue instead
	of busy looping
Date: Tue, 31 Jul 2007 12:00:31 +0200
Message-ID: <20070731100031.GA3462@elf.ucw.cz>
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To: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Nigel Cunningham <nigel@nigel.suspend2.net>, Andres Salomon <dilinger@debian.org>, pm list <linux-pm@lists.linux-foundation.org>, Chris Ball <cjb@laptop.org>, David Woodhouse <dwmw2@infradead.org>, Oleg Nesterov <oleg@tv-sign.ru>
List-Id: linux-pm@vger.kernel.org

Hi!

> > Ok, could we just do schedule_timeout(HZ/10) or something, but when we
> > _know_ we woke someone, wakeup() that task? No new variables, keep
> > existing logic.
> 
> The logic doesn't change that much. :-)
> 
> > That should still get most of the benefits, and be two liner, no?
> 
> Well, I think we can avoid using refrigerator_called, if this is a problem, but
> the patch won't be a two liner.

Sure? The current process is ineffective because it polls. If we add
schedule_timeout(HZ/10), we'll have still correct freezer (and it will
not waste power any more), but it will delay freezing by HZ/20 on
average.

If we add wakeup() at strategic place, we should get rid of that delay...

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html