Message-Id: <201009281006.49727.Martin@lichtvoll.de>
Date:	Tue, 28 Sep 2010 10:06:40 +0200
From:	Martin Steigerwald <Martin@...htvoll.de>
To:	Nigel Cunningham <nigel@...onice.net>
Cc:	linux-pm@...ts.linux-foundation.org,
	LKML <linux-kernel@...r.kernel.org>,
	"TuxOnIce-devel" <tuxonice-devel@...onice.net>
Subject: Re: [TuxOnIce-devel] [linux-pm] [PATCH] Hibernate:  Implement readahead when resuming

Am Sonntag 26 September 2010 schrieb Nigel Cunningham:
> Hi.
> 
> On 26/09/10 08:10, Martin Steigerwald wrote:
> > Hi Nigel.
> > 
> > Am Samstag 25 September 2010 schrieb Nigel Cunningham:
> >> On 26/09/10 05:58, Martin Steigerwald wrote:
> >>> Am Samstag 25 September 2010 schrieb Martin Steigerwald:
> >>>> Hi Nigel and Rafael,
> >>>> 
> >>>> Am Samstag 25 September 2010 schrieb Nigel Cunningham:
> >>>>> Add support for submitting reads before they're needed. This
> >>>>> greatly improves the speed of resuming:
> >>>>> 
> >>>>> From
> >>>>> 
> >>>>> PM: Image read at 66 MB/s.
> >>>>> 
> >>>>> to
> >>>>> 
> >>>>> PM: Image read at 229 MB/s.
> >>>>> 
> >>>>> ...and removes the need for the sync_read flag.
> >>>> 
> >>>> So
> >>>> 
> >>>> martin@...mbhala:~/Computer/Shambhala/Kernel/2.6.36/tuxonice-head>
> >>>> git branch -av | grep for-rafael
> >>>> * for-rafael                      d4e7490 Hibernate: Implement
> >>>> readahead when resuming
> >>>> 
> >>>>     remotes/origin/for-rafael       d4e7490 Hibernate: Implement
> >>>> 
> >>>> readahead when resuming
> >>> 
> >>> [...]
> >>> 
> >>>> basically seems to work.
> >>> 
> >>> [...]
> >>> 
> >>>> I tried 5 times:
> >>>> 
> >>>> - one with just kdm started worked nicely and really rather fast!
> >>>> 
> >>>> - four with a full blown KDE 4.5.1 session with OpenGL compositing
> >>>> 
> >>>>     - one seemed to hang prior to reinitializing the Radeon KMS
> >>>>     DRM setup - three other worked just fine
> >>>> 
> >>>> I do not think that the hang is related to your changes, Nigel.
> >>>> The kernel remained stuck at the lower initial resolution and
> >>>> didn't seem to initialize the radeon KMS framebuffers at
> >>>> 1400x1050 properly. I didn't see this with 2.6.35 and userspace
> >>>> software suspend.
> >>> 
> >>> I am not so sure anymore.
> >>> 
> >>> I got another one of these hangs with the 2.6.36-rc5 mentioned
> >>> above. See IMG_3871.jpg for the exact display were it hung. I was
> >>> able to switch view with Alt-F1 or something like that. And then
> >>> got IMG_3873.jpg. But nothing happened anymore. Find these on:
> >>> 
> >>> http://martin-steigerwald.de/tmp/tuxonice/hang-after-resume-with-pm
> >>> - patches-for-rafael/
> >>> 
> >>> I now tried in kernel suspend to disk with
> >>> 
> >>> martin@...mbhala:~>   cat /proc/version
> >>> Linux version 2.6.35.5-tp42-vmembase-0-pm-avoid-oom-dirty
> >>> (martin@...mbhala) (gcc version 4.4.5 20100728 (prerelease) (Debian
> >>> 4.4.4-8) ) #4 PREEMPT Sat Sep 25 13:29:53 CEST 2010
> >>> 
> >>> which doesn't contain your patches, Nigel, for about 5 or 6 times
> >>> and I did not see that hang.
> >>> 
> >>> So maybe something in your patches, even if just the debug output I
> >>> mentioned, or something in 2.6.36-rc5 triggers that hang.
> >>> 
> >>> I will test 2.6.35.5 for a bit longer to make sure that there is no
> >>> hang on resume prior to loading. I need to reboot this one now too,
> >>> cause after one of the resume attempts USB stopped working with:
> >>> 
> >>> Sep 25 21:36:47 shambhala kernel: usb 1-3: New USB device found,
> >>> idVendor=1307, idProduct=0330
> >>> Sep 25 21:36:47 shambhala kernel: usb 1-3: New USB device strings:
> >>> Mfr=1, Product=2, SerialNumber=3
> >>> Sep 25 21:36:47 shambhala kernel: usb 1-3: Product: Mass Storage
> >>> Device Sep 25 21:36:47 shambhala kernel: usb 1-3: Manufacturer:
> >>> Generic Sep 25 21:36:47 shambhala kernel: usb 1-3: SerialNumber:
> >>> 00000000000006 Sep 25 21:36:47 shambhala kernel: scsi3 :
> >>> usb-storage 1-3:1.0 Sep 25 21:36:48 shambhala kernel: BUG: unable
> >>> to handle kernel NULL pointer dereference at 0000002c
> >>> Sep 25 21:36:48 shambhala kernel: IP: [<c125b5de>]
> >>> cfq_get_queue+0x33e/0x550
> >>> Sep 25 21:36:48 shambhala kernel: *pde = 00000000
> >>> Sep 25 21:36:48 shambhala kernel: Oops: 0000 [#1] PREEMPT
> > 
> > [...]
> > 
> >>> exited with preempt_count 1
> >>> 
> >>> Maybe the USB system has an powermanagement related issue that in
> >>> kernel suspend triggers more easily than userspace software
> >>> suspend? I didn't see this one before. But well, this is a bug I
> >>> will report in
> >>> bugzilla.kernel.org.
> >>> 
> >>> Ciao,
> >> 
> >> Okay. Can you try without the last patch, and confirm that it's
> >> reliable (albeit slower) then?
> > 
> > Well as I told already (later on) the USB problem seems to be related
> > to my testing of systemd in Debian - I do not get how this could be
> > the case, but it works, when I remove init=/bin/systemd. I think I
> > will report this as a kernel bug nonetheless, cause when I apply
> > that "userspace shouldn't be able to let the kernel oops" paradigm
> > then its a kernel bug.
> > 
> > Should I test without the readahead patch regarding whether that hang
> > after resume, prior to activating Radeon KMS framebuffer is fixed as
> > well?
> 
> Yes, please. I only whipped up the readahead patch last night. Since
> it's single threaded, there's a lot less to go wrong compared to
> TuxOnIce, but it's still possible that there's some bug I haven't
> noticed yet. It would be good to be able to see it's definitely that
> patch.
> 
> > I am a bit unsure on what to test next. My current thoughts are:
> > 
> > - Test whether 2.6.35.5 is stable with unpatched in kernel suspend.
> > Currently in progress. Cause before that I only know its stable with
> > userspace software suspend.
> > 
> > - Apply your patches on top of 2.6.35.5 and test that.
> > 
> >    - If that works, it appears to be a problem introduced by
> >    2.6.36-rc5
> >    
> >      - Then I'd possibly test 2.6.36-rc5 with unpatched in kernel
> >      suspend.
> >    
> >    - If that doesn't work, it appears to be an issue with your
> >    patches
> >    
> >      - Then I test without readahead patch.
> > 
> > Tell me when you have any different suggestions.
> > 
> > Ciao,
> 
> I'd start with 2.6.36-rc5 unpatched, and only fall back to 2.6.35 if
> that's unreliable.

Done so. 2.6.36-rc5-tp42-vmembase-0-dirty without your pm patches is 
stable. So these hangs on resume seem somehow related to your patches or 
to the debug output that you left in.

Now compiling

martin@...mbhala:~/Computer/Shambhala/Kernel/2.6.36/tuxonice-head> git 
branch -v 
* (no branch) 3394a84 Hibernation: Remove now-empty routines.
[...]

Which is one commit before

  for-rafael  14c1209 Hibernate: Implement readahead when resuming

I also enabled CONFIG_PM_DEBUG and CONFIG_PM_ADVANCED_DEBUG.

Tell me, when I instead should try that suspend-next stuff. ;)

Ciao,
-- 
Martin 'Helios' Steigerwald - http://www.Lichtvoll.de
GPG: 03B0 0D6C 0040 0710 4AFA  B82F 991B EAAC A599 84C7

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