From: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
To: Gleb Natapov <gleb@redhat.com>
Cc: Avi Kivity <avi@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
LKML <linux-kernel@vger.kernel.org>, KVM <kvm@vger.kernel.org>
Subject: Re: [PATCH 4/8] KVM: avoid unnecessary wait for a async pf
Date: Thu, 28 Oct 2010 15:06:26 +0800 [thread overview]
Message-ID: <4CC920F2.4080008@cn.fujitsu.com> (raw)
In-Reply-To: <20101027104210.GN26191@redhat.com>
On 10/27/2010 06:42 PM, Gleb Natapov wrote:
> On Wed, Oct 27, 2010 at 05:04:58PM +0800, Xiao Guangrong wrote:
>> In current code, it checks async pf completion out of the wait context,
>> like this:
>>
>> if (vcpu->arch.mp_state == KVM_MP_STATE_RUNNABLE &&
>> !vcpu->arch.apf.halted)
>> r = vcpu_enter_guest(vcpu);
>> else {
>> ......
>> kvm_vcpu_block(vcpu)
>> ^- waiting until 'async_pf.done' is not empty
>> }
>>
>> kvm_check_async_pf_completion(vcpu)
>> ^- delete list from async_pf.done
>>
>> So, if we check aysnc pf completion first, it can be blocked at
>> kvm_vcpu_block
>>
> Correct, but it can be fixed by adding vcpu->arch.apf.halted = false; to
> kvm_arch_async_page_present(), no?
> Adding kvm_check_async_pf_completion() to arch independent kvm_vcpu_block()
> constrains how other archs may implement async pf support IMO.
>
Um, i think it's reasonable, will fix it address your comment.
next prev parent reply other threads:[~2010-10-28 7:02 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-27 9:01 [PATCH 1/8] KVM: fix tracing kvm_try_async_get_page Xiao Guangrong
2010-10-27 9:02 ` [PATCH 2/8] KVM: cleanup aysnc_pf tracepoints Xiao Guangrong
2010-10-27 10:10 ` Gleb Natapov
2010-10-27 9:03 ` [PATCH 3/8] KVM: fix searching async gfn in kvm_async_pf_gfn_slot Xiao Guangrong
2010-10-27 10:29 ` Gleb Natapov
2010-10-27 9:04 ` [PATCH 4/8] KVM: avoid unnecessary wait for a async pf Xiao Guangrong
2010-10-27 10:42 ` Gleb Natapov
2010-10-28 7:06 ` Xiao Guangrong [this message]
2010-10-27 9:05 ` [PATCH 5/8] KVM: don't touch vcpu stat after async pf is complete Xiao Guangrong
2010-10-27 10:44 ` Gleb Natapov
2010-10-28 7:35 ` Xiao Guangrong
2010-10-28 7:41 ` Gleb Natapov
2010-10-27 9:07 ` [PATCH 6/8] KVM: simply wakup async pf Xiao Guangrong
2010-10-27 10:50 ` Gleb Natapov
2010-10-28 7:59 ` Xiao Guangrong
2010-10-27 9:09 ` [PATCH 7/8] KVM: make async_pf work queue lockless Xiao Guangrong
2010-10-27 11:41 ` Gleb Natapov
2010-10-28 9:08 ` Xiao Guangrong
2010-10-28 9:14 ` Gleb Natapov
2010-10-27 9:10 ` [PATCH 8/8] KVM: add debugfs file to show the number of async pf Xiao Guangrong
2010-10-27 10:58 ` Gleb Natapov
2010-10-28 9:09 ` Xiao Guangrong
2010-10-27 9:59 ` [PATCH 1/8] KVM: fix tracing kvm_try_async_get_page Gleb Natapov
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