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?
Regards,
Anthony Liguori
Pekka
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