Re: virtio_net hang

[Emmanuel Lacour <elacour@easter-eggs.com>]

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 :(

Like answered a few minutes ago, I will try a 2.6.27.6 in the guest
today and let you know on the first problem I encounter if any ;)