Re: [PATCH v6 2/3] KVM: dynamic halt_poll_ns adjustment

From: David Matlack
Date: Thu Sep 03 2015 - 12:08:07 EST


On Thu, Sep 3, 2015 at 2:23 AM, Wanpeng Li <wanpeng.li@xxxxxxxxxxx> wrote:
>
> How about something like:
>
> @@ -1941,10 +1976,14 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
> */
> if (kvm_vcpu_check_block(vcpu) < 0) {
> ++vcpu->stat.halt_successful_poll;
> - goto out;
> + break;
> }
> cur = ktime_get();
> } while (single_task_running() && ktime_before(cur, stop));
> +
> + poll_ns = ktime_to_ns(cur) - ktime_to_ns(start);
> + if (ktime_before(cur, stop) && single_task_running())
> + goto out;

I would prefer an explicit signal (e.g. set a bool to true before breaking out
of the loop, and check it here) to avoid duplicating the loop exit condition.
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