On 02/07/2011 06:34 AM, Avi Kivity wrote:
On 02/04/2011 10:56 AM, Jan Kiszka wrote:
>
> This should be a rare event. If you are missing 50% of your
> notifications, not amount of gradual catchup is going to help you
out.
But that's the only thing this patch is after: lost ticks at QEMU level.
Most lost ticks will happen at the vcpu level. The iothread has low
utilization and will therefore be scheduled promptly, whereas the vcpu
thread may have high utilization and will thus be preempted. When it
is preempted for longer than the timer tick, we will see vcpu-level
coalescing. All it takes is 2:1 overcommit to see time go half as
fast; I don't think you'll ever see that on bare metal.
But that's not to say that doing something about lost ticks in QEMU
isn't still useful.
Regards,
Anthony Liguori
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