linux-kernel - Re: does hibernate to disk try hard enough to free memory?

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Date:	Sat, 5 Mar 2011 15:41:44 +0100
From:	Martin Steigerwald <Martin@...htvoll.de>
To:	linux-kernel@...r.kernel.org
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>,
	Linux PM mailing list <linux-pm@...ts.linux-foundation.org>
Subject: Re: does hibernate to disk try hard enough to free memory?

Am Wednesday 23 February 2011 schrieb Rafael J. Wysocki:
> On Wednesday, February 23, 2011, Martin Steigerwald wrote:
> > Am Tuesday 22 February 2011 schrieb Rafael J. Wysocki:
> > > On Tuesday, February 22, 2011, Martin Steigerwald wrote:
> > > > Am Tuesday 22 February 2011 schrieb Rafael J. Wysocki:
> > > > > On Tuesday, February 22, 2011, Martin Steigerwald wrote:
> > > > > > Hi!
> > > > > > 
> > > > > > Since Radeon KMS I often have it that my ThinkPad T42 with 2
> > > > > > MiB of RAM is not able to allocate memory for the
> > > > > > hibernation image. Before KMS hibernation only very rarely
> > > > > > failed for that reason.
> > > > > > 
> > > > > > Often I run without compositing at all as I believe this
> > > > > > might spare some pages as well. But this doesn't always
> > > > > > help.
> > > > > > 
> > > > > > It complains that to less pages could be freed. For example
> > > > > > with kernel 2.6.37:
> > > > > > 
> > > > > > Feb 16 00:15:00 shambhala kernel: PM: Creating hibernation
> > > > > > image: Feb 16 00:15:00 shambhala kernel: PM: Need to copy
> > > > > > 186577 pages Feb 16 00:15:00 shambhala kernel: PM: Normal
> > > > > > pages needed: 114411 + 1024, available pages: 112767
> > > > > > Feb 16 00:15:00 shambhala kernel: PM: Not enough free memory
> > > > > > Feb 16 00:15:00 shambhala kernel: PM: Error -12 creating
> > > > > > hibernation image Feb 16 00:15:00 shambhala kernel: Extended
> > > > > > CMOS year: 2000 Feb 16 00:15:00 shambhala kernel: ACPI:
> > > > > > Waking up from system sleep state S4
> > > > > > Feb 16 00:15:00 shambhala kernel: PM: early recover of
> > > > > > devices complete after 0.376 msecs
> > > > > 
> > > > > What's the value in /sys/power/image_size?
> > > > 
> > > > shambhala:~> cat /sys/power/image_size
> > > > 844206080
> > > > 
> > > > Should I try with less?
> > > 
> > > Yes, please.  Try with 700000000 for example.
> > 
> > I replaced dropping by settings image_size to this valua and the
> > ThinkPad hibernated with KMail open. Thus seems to work, but I will
> > test a bit further.
> > 
> > Where does the higher value previously set come from? Autotuning?
> 
> Likely.  The number seems to match at least.
> 
> > Is there anything that can be improved with autotuning?
> 
> We can lower the ratio of the image size to the total RAM.
> Alternatively, we can increase SPARE_PAGES.
> 
> > If yes, I can file a bug report.
> 
> Yes, please.

Reported-as:

Bug 30482 - try harder to free enough memory / improve image size 
autotuning

> > Otherwise I just try to find a good value for image size and be
> > done with it.
> 
> It would be helpful if you could determine the greatest image size
> working for you.

I am at 710000000 at the moment. See bug report.

I got the occassional hang on hibernation that I reported somewhere else. 
You hinted at that the kernel has problems to free enough memory and takes 
long to do that. I waited for minutes. Will report this as a different bug 
and link it from there.

Thanks,
-- 
Martin 'Helios' Steigerwald - http://www.Lichtvoll.de
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