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Subject: Re: [PATCH v5] KVM: halt-polling: poll for the upcoming fire timers
To: yunhong jiang <yunhong.jiang@linux.intel.com>
References: <1464144467-6714-1-git-send-email-wanpeng.li@hotmail.com>
 <c66b94e0-45db-b8bd-1d63-c3d781afd5ce@redhat.com>
 <20160526133331.5aadf122@jnakajim-build>
Cc: Wanpeng Li <kernellwp@gmail.com>, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org, Wanpeng Li <wanpeng.li@hotmail.com>,
        =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        David Matlack <dmatlack@google.com>,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        Yang Zhang <yang.zhang.wz@gmail.com>
From: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <0c7c9b5a-ce15-196b-e83e-627348f04d55@redhat.com>
Date: Fri, 27 May 2016 11:49:26 +0200
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On 26/05/2016 22:33, yunhong jiang wrote:
> On Thu, 26 May 2016 12:26:27 +0200
> Paolo Bonzini <pbonzini@redhat.com> wrote:
> 
>>
>>
>> On 25/05/2016 04:47, Wanpeng Li wrote:
>>> From: Wanpeng Li <wanpeng.li@hotmail.com>
>>>
>>> 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 irc.oftc.net.

Thanks,

Paolo