linux-kernel - Re: [RFC] sleepy linux

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Message-ID: <20071226203258.GE8094@elf.ucw.cz>
Date:	Wed, 26 Dec 2007 21:32:58 +0100
From:	Pavel Machek <pavel@....cz>
To:	Oliver Neukum <oliver@...kum.org>
Cc:	kernel list <linux-kernel@...r.kernel.org>,
	Linux-pm mailing list <linux-pm@...ts.osdl.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>
Subject: Re: [RFC] sleepy linux

On Wed 2007-12-26 21:23:37, Oliver Neukum wrote:
> Am Mittwoch, 26. Dezember 2007 21:17:22 schrieb Pavel Machek:
> > On Wed 2007-12-26 18:28:04, Oliver Neukum wrote:
> > > Am Mittwoch, 26. Dezember 2007 00:07:31 schrieb Pavel Machek:
> > > > Heute 00:07:31
> > > >    
> > > > This is RFC. It does not even work for me... it sleeps but it will not
> > > > wake up, because SATA wakeup code is missing. Code attached for illustration.
> > > > 
> > > > I wonder if this is the right approach? What is right interface to the
> > > > drivers?
> > > 
> > > IMHO you are making to many special cases. The system can be "sleepy"
> > > if all devices can be runtime suspended and all CPUs are idle.
> > 
> > Is there an easy way to tell if all the devices are runtime suspended?
> 
> Do you really want to know whether they are suspended or whether they
> could be suspended?

If they are suspended.

My plan is: let the drivers autosuspend on their own. If I see all of
them are autosuspended, then it looks like great time to put whole
system into s2ram...

> > I guess I need to know from atomic context :-(.
> 
> Urgh. suspend() must be able to sleep and can fail.

That's ok.

... I also don't need to call any suspend() routines, because all the
drivers are already suspended, right?

And yes, I want device activity to prevent s2ram. If user is burning
CD, machine should not sleep. If user is actively typing, machine
should not sleep. My vision is: screen saver tells kernel keyboard
need not be very responsive, at that point keyboard driver can
autosuspend the keyboard, and if that was the last device, whole
system sleeps.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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