Re: High Net and Disk Use == stuck domain

["Christopher S. Aker" <caker@theshore.net>]

Christopher S. Aker wrote:
> For the past year or so we've been seeing a bug whereby a domU's CPU 
> would spin up to a steady 100, 200, 300 or 400% (4 vcpus), console would 
> freeze, and some or all of the network-facing services within the domU 
> would connect but block without any output.  Disk IO would flatline. The 
> domU would never recover and required rebooting.
> 
> Since pv_ops hasn't always been around, we previously had only seen this 
> behavior with xen-patched domUs (2.6.18.x), but now we're seeing it with 
> pv_ops.  Identical symptoms.  And, I have a user that is able to 
> reliable reproduce it on 2.6.27.4!
> 
> His recipe is downloading an ISO from a very fast and close-by news 
> server using nzbget.  The trigger appears to be a combination of high 
> network use and high disk use (like download from a very fast mirror) -- 
> because we weren't able to reproduce the problem when saving to a tmpfs 
> mount.
> 
> I was able to grab the output of sysrq t while it was in the bad state:
> 
> http://theshore.net/~caker/xen/BUGS/D-state/console.log
> 
> The number of processes in D state (39) is quite suspicious.
> 
> Let me know if there's anything else I can provide.
> 
> -Chris

Jeremy,

Did this one slip by you?  I figured a reproducible bug would be just 
too tantalizing to resist.

What's the correct venue for these issues that overlap xen-devel, lkml, 
and virtualization/pv_ops stuff -- should I be blasting these to everybody?

-Chris