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

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Saturday, March 05, 2011, Martin Steigerwald wrote:
> 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

I attached a patch for you to test to the bug entry.

Thanks,
Rafael