linux-kernel - Re: High power consumption after suspend/resume cycle

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Message-ID: <20091121190520.GB2444@ucw.cz>
Date:	Sat, 21 Nov 2009 20:05:20 +0100
From:	Pavel Machek <pavel@....cz>
To:	Andrew Lutomirski <luto@....edu>
Cc:	linux-kernel@...r.kernel.org, linux-thinkpad@...ux-thinkpad.org
Subject: Re: High power consumption after suspend/resume cycle

Hi!

> I'm running a git kernel that's slightly newer than 2.6.32-rc1.
> 
> First, thanks for all the great work everywhere on laptop power
> consumption -- on my Lenovo X200s, it looks like Linux is getting
> close to Windows (Windows wins by about 0.7W, except that its power
> usage frequently spikes since Windows apparently still doesn't know
> how to sit still and do nothing, whereas Linux's seems more stable.).
> Windows after a reboot, even running KDE with compositing enabled and
> while connected to wifi, at least after some tweaking.
> 
> There's a catch, though: after a suspend/resume cycle, power
> consumption goes up by over well over a watt.  (On a system that draws
> about 7 watts before suspending, that's a big deal.)  I've tried
> turning off X, suspending with 'echo mem > /sys/power/state' to avoid
> any distro scripts running, and manually restoring SATA power saving
> settings, but it still happens.  I even tried unbinding e1000e and
> both USB drivers, unloading the i2400 (wimax) driver, iwlagn, and
> iwlcore, and it still happens.  This is 100% reproducible, and I'd be
> happy to test things.
> 
> This could be a BIOS bug I suppose (although I'm running the latest
> BIOS), but Windows 7 does not have this problem at all.
> 
> Any ideas about what to try or what subsystem to blame?

Well, on thinkpad x60 power consumption is .3W *lower*.

You could try comparing lspci -vvv before and after... but this is
deep magic and hard to debug. 

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