Re: T400 suspend/resume regression -- bisected to a mystery mergecommit

From: Theodore Tso
Date: Mon Sep 28 2009 - 09:51:39 EST


On Sun, Sep 27, 2009 at 06:13:42PM +0200, Rafael J. Wysocki wrote:
>
> commit c7121843685de2bf7f3afd3ae1d6a146010bf1fc
> Author: Magnus Damm <magnus.damm@xxxxxxxxx>
> Date: Tue Jul 28 14:09:55 2009 -0700
>
> clocksource: Save mult_orig in clocksource_disable()
>
> Please try to revert it and retest.

Using Linus's suggested technique, I bisected it down to this commit:

Author: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Date: Fri Aug 14 15:47:30 2009 +0200

timekeeping: Update clocksource with stop_machine

update_wall_time calls change_clocksource HZ times per second to check
if a new clock source is available. In close to 100% of all calls
there is no new clock. Replace the tick based check by an update done
with stop_machine.

Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Acked-by: John Stultz <johnstul@xxxxxxxxxx>
Cc: Daniel Walker <dwalker@xxxxxxxxxx>
LKML-Reference: <20090814134810.711836357@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>

Unfortunately there are a bunch of patches I'm trying to get in shape
to push to Linus (the merge window coincided unfortunately with
LinuxCon/Plumbeer's so I'm a bit behind) so I haven't had a chance to
take it further. I'll try reverting each of the above two patches,
and report back in a day or two.

- Ted
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