Re: [Xen-users] i/o scheduler deadlocks with loopback devices

[Nathan Gamber <ngamber@xxxxxxxxxxxxx>]

 Thomas,

2.6.18-164.6.1.el5xen on CentOS 5.


Nathan

On 11/05/10 13:48, Thomas Halinka wrote:
> Hi Natham,
>
> which kernel is ur dom0 running?
>
> cu,
>
> thomas
>
>
> Am Freitag, den 05.11.2010, 13:30 -0400 schrieb Nathan Gamber:
> > This was an email I sent to xen-devel a while ago without getting a
> > response. I'm reposting it here in case someone knows more.
> >
> >    Hello all,
> >
> > I'm able to consistently reproduce lockups in my domU with heavy I/O
> > with the following error:
> >
> > 36841.420662] INFO: task rsyslogd:15014
> > blocked for more than 120 seconds. [36841.420843] "echo 0>
> > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> >
> > The task varies between any of the tasks that might be active
> > (kjournald, loop0, etc.)
> >
> > My setup is:
> > Xen dom0  version 3.4.2.
> > domU: Ubuntu 10.04, 2.6.36-rc6 based on Stefano Stabellini's
> > v2.6.36-rc6-urgent-fixes tree.
> > Paravirtual disks and network interfaces.
> > Root filesystem on /dev/xvda3, formatted ext3, mounted with default options.
> > Both dom0 and domU are using the CFQ i/o scheduler.
> >
> > The xvbd is based on LVM, on top of a local SATA RAID array.
> >
> >
> > To produce this, I can do one of the following:
> >
> > Set up domU as a primary drbd node, with my drbd volume on top of a
> > local loopback device, and then rsync many files to the volume, delete
> > them, and repeat until the crash.
> >
> > Mount a linux iso via loopback on a /mnt/test, rsync /mnt/test/ to
> > another directory on xvda3, delete the files, and then repeat until the
> > crash.
> >
> > This is very similar to the following situation:
> >
> > http://www.amailbox.org/mailarchive/linux-kernel/2010/9/1/4614107
> >
> > Jeremy Fitzhardinge replied to that thread, indicating that his "xen:
> > use percpu interrupts for IPIs and VIRQs" and "xen: handle events as
> > edge-triggered" patches should fix the issue. These were introduced into
> > 2.6.36-rc3, I believe, and the issue persists. Disabling irqbalanced in
> > dom0, as he suggested as a workaround, has no effect. I've also tried
> > changing the scheduler, and reducing the number of vcpus from 4 to 1,
> > which also had no effect.
> >
> > Regards,
> >
> > Nathan Gamber
> >
> > _______________________________________________
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> > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-devel
> >
> >
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>
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