Re: [Xen-devel] High Net and Disk Use == stuck domain

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

Christopher S. Aker wrote:
> 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.
Hoping it would go away by itself? ;)

I'm trying to repro it now, copying ISOs at 25 Mbytes/sec.  How long 
does it take to happen?
> 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?
Me and xen-devel are a good start, and posting in a bugzilla cc:ing me 
if it looks like its been dropped on the floor.
   J

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