On Sat, May 7, 2011 at 6:01 PM, Anthony Liguori <aliguori@xxxxxxxxxx> wrote: > On 05/07/2011 09:50 AM, Pekka Enberg wrote: >> >> On Sat, 2011-05-07 at 08:14 -0500, Anthony Liguori wrote: >>> >>> It seems like this patch is simply avoiding raising the interrupt line >>> if the ISR has not been acknowledged yet. I don't think there's a >>> functional issue here but I'm surprised that it's a win. There should >>> be a very short window when the interrupt is lowered in the APIC but >>> still not acknowledged in the ISR. >>> >>> You should just be saving a pretty cheap system call. I wonder if the >>> system call is taking longer than it should.. >> >> The patch seems to fix a bug where the guest kernel breaks down under >> interrupt storm and stops doing VIRTIO_PCI_QUEUE_NOTIFY. We assumed it >> was something with our code but your comments make me wonder if there's >> a real problem in KVM_IRQ_LINE. > > Stops doing it for a short period of time or entirely? Seems to be entirely. The test case is doing "ping -f" from host to guest and vice versa and it takes 30-60 seconds to trigger for me. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
