Re: [PATCH v5] KVM: halt-polling: poll for the upcoming fire timers

From: Paolo Bonzini
Date: Fri May 27 2016 - 05:49:36 EST

On 26/05/2016 22:33, yunhong jiang wrote:
> On Thu, 26 May 2016 12:26:27 +0200
> Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote:
>> On 25/05/2016 04:47, Wanpeng Li wrote:
>>> From: Wanpeng Li <>
>>> If an emulated lapic timer will fire soon(in the scope of 10us the
>>> base of dynamic halt-polling, lower-end of message passing workload
>>> latency TCP_RR's poll time < 10us) we can treat it as a short halt,
>>> and poll to wait it fire, the fire callback apic_timer_fn() will set
>>> KVM_REQ_PENDING_TIMER, and this flag will be check during busy poll.
>>> This can avoid context switch overhead and the latency which we wake
>>> up vCPU.
>> As discussed on IRC, I would like to understand why the adaptive
> Glad to know the IRC channel. Is #kvm channel on freenode the IRC you are
> talking about?

No, it's #qemu on