On Fri, Apr 29, 2011 at 1:32 PM, Ingo Molnar <mingo@xxxxxxx> wrote:
>>> Without the mutex around the kvm__irq_line, I am still seeing the
>>> hangs(with the irq assertion movement patch).
>>
>> since the mutex has no effect on the other party that modifies the virtual
>> queue (the guest OS), this at best only changes timings and hides the bug.
On Fri, Apr 29, 2011 at 1:42 PM, Pekka Enberg <penberg@xxxxxxxxxx> wrote:
> Yes, I don't think it has anything to do with the queues - it's simply
> a bug in the RX path which requires other work to happen to raise the
> IRQ.
Turns out thread pool isn't related to the problem. Asias and Sasha
reported that the problem triggers even with all the thread pool code
reverted. I'm guessing it's a latent bug in the virtio network driver
that got exposed by Cyrill's patch. It seems to be related to IRQ
handling and I still think it's related to assuming
VIRTIO_PCI_QUEUE_NOTIFY will be triggered for the RX path.
Pekka
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