linux-kernel - Re: [PATCH] SATA / AHCI: Do not play with the link PM during suspend to RAM

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Message-ID: <201008261815.34574.stephan.diestelhorst@amd.com>
Date:	Thu, 26 Aug 2010 18:15:34 +0200
From:	Stephan Diestelhorst <stephan.diestelhorst@....com>
To:	Tejun Heo <htejun@...il.com>
CC:	"Rafael J. Wysocki" <rjw@...k.pl>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-ide@...r.kernel.org" <linux-ide@...r.kernel.org>,
	"linux-pm@...ts.osdl.org" <linux-pm@...ts.osdl.org>,
	Stephan Diestelhorst <stephan.diestelhorst@...il.com>
Subject: Re: [PATCH] SATA / AHCI: Do not play with the link PM during suspend to RAM

On Tuesday 24 August 2010 18:11:22 Stephan Diestelhorst wrote:
> On Tuesday 24 August 2010 18:07:23 Stephan Diestelhorst wrote:
> > On Monday 23 August 2010 14:03:40 Tejun Heo wrote:
> > > On 08/19/2010 06:23 PM, Stephan Diestelhorst wrote:
> > > > It says "max_performance", I have not touched anyhting. So it has been
> > > > like that all the time. Would this explain why your patch did not show
> > > > the debug printout?
> > > 
> > > Hmm... okay.  Yeah, if you haven't been using IPM at all, there won't
> > > be any debug messages but at the same time the posted patch should
> > > have had the same effect as Rafael's patch as IPM path isn't traveled
> > > at all.  Can you please check the followings?
> > > 
[...]
> > > * Rafael's patch actually fixes the problem.  If you haven't been
> > >   using IPM at all, Rafael's patch and mine should behave exactly the
> > >   same (ie. no IPM operation at all during suspend/resume).  It could
> > >   be that you're seeing a different issue.
> > 
> > That next on my list...

Just did the following: Rebased Rafaels patch to 2.6.35 and tried it
again (with added prints to make sure I am running the right one) and
did >10 suspend to ram / resume cycles under I/O write load. All of
them worked fine (for comparison: your patch resulted in RO HDD at
first attempt).

(I had some extra prints around the suspend functions changed in
 Rafael's patch, tried with and without, no change--works flawlessly.)

What do you make of this?

Thanks,
  Stephan
-- 
Stephan Diestelhorst, AMD Operating System Research Center
stephan.diestelhorst@....com, Tel. +49 (0)351 448 356 719

Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach
General Managers: Alberto Bozzo, Andrew Bowd
Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632

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