On Thu, Nov 20, 2008 at 12:36:50PM +0100, Emmanuel Lacour wrote:
> On Wed, Nov 19, 2008 at 07:03:09PM +0000, Mark McLoughlin wrote:
> >
> > I had a look at Emmanuel's strace log and it shows that qemu isn't
> > selecting on the tapfd, presumably because virtio_net_can_receive() sees
> > that we've exhausted all available receive buffers.
> >
> > When qemu does poll the tapfd (after an ifdown/ifup in the guest), there
> > are a load of packets waiting in the queue and things proceed as normal.
> >
> > That still jives with the theory that we're somehow getting into a state
> > where NAPI polling is de-scheduled while guest rx interrupts are also
> > disabled.
> >
> > > Is it possible for you to try a newer guest kernel?
> >
> > If you can try a newer kernel, or even try some debugging patches, that
> > would help a lot.
> >
>
> The difficulty is that I can not always reproduce the bug.
>
> But another interesting think is that I switched to e1000 and I had
> another lock after that with same symptoms :(
Same symptoms with the rtl8139 and kvm-userspace 78 running on 2.6.24
(kvm modules from kvm 78), I wasn't able to reproduce this with kvm 63
(nor did I find the time to do any further debugging yet).
Cheers,
-- Guido
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