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

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Date:	Fri, 2 Oct 2009 13:44:37 -0400
From:	Andrew Lutomirski <luto@....edu>
To:	linux-kernel@...r.kernel.org, linux-thinkpad@...ux-thinkpad.org
Subject: High power consumption after suspend/resume cycle

Hi all-

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?

I'm running Fedora 11 if that makes any difference.

Thanks,
Andy
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