Re: pvops domu soft lockup under load (more logs)

[Jeremy Fitzhardinge <jeremy@goop.org>]

On 04/15/2010 03:56 AM, Pim van Riezen wrote:
> On Apr 14, 2010, at 19:48 , Jeremy Fitzhardinge wrote:
>
>   
>> Does it appear on the Xen console (visible with "xm dmesg")?  You may
>> need to do a sysrq '9' first to get it to output all messages.
>>     
> Does that sysrq have to go to dom0 or to the domU?
>   

To the locked-up domU.

> I also got the tip from someone on xen-users to take a look at the clock source, and setting /sys/devices/system/clocksource/clocksource0/current_clocksource to 'jiffies' does seem to stop the lockups from happening. The fact that I've witnessed other kernel timekeeping going wonky on these guests, the fact that this helps does seem intuitively right, but I don't know if it gives you enough to work with.
>   

I've seen similar lockups at a very low rate.  The clocksource
workaround just confuses me; the whole thing stumps me.  The main piece
of evidence I haven't managed to get yet is a complete process dump
(sysrq-t) to see who's waiting on what.

Also, could you try 2.6.32.11, which has some timer-related fixes in it,
that may or may not help.

    J