On Wed, 4 May 2016 09:50:57 +0200
Christian Borntraeger <borntraeger@xxxxxxxxxx> wrote:
> The feedback about the logic triggered some more experiments on my side.
> So I was experimenting with some different workloads/heuristics and it
> seems that even more aggressive shrinking (basically resetting to 0 as soon
> as an invalid poll comes along) does improve the cpu usage even more.
Do we still keep the shrink instead of resetting to 0 explicitly? (In
case the default shrink factor was set to != 0.) We'd lose a tuneable,
but it seems the aggressiveness is warranted.
> (So the new diff looks like)
> @@ -2034,7 +2036,9 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
> out:
> block_ns = ktime_to_ns(cur) - ktime_to_ns(start);
>
> - if (halt_poll_ns) {
> + if (!vcpu_valid_wakeup(vcpu))
> + shrink_halt_poll_ns(vcpu);
> + else if (halt_poll_ns) {
> if (block_ns <= vcpu->halt_poll_ns)
> ;
...making this
if (halt_poll_ns && vcpu_valid_wakeup(vcpu)) {
--
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