linux-kernel - Re: [PATCH v2 0/22] KVM: optimize for MMIO handled

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Message-ID: <4E0AEF29.7080706@redhat.com>
Date:	Wed, 29 Jun 2011 12:23:53 +0300
From:	Avi Kivity <avi@...hat.com>
To:	Xiao Guangrong <xiaoguangrong@...fujitsu.com>
CC:	Marcelo Tosatti <mtosatti@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>, KVM <kvm@...r.kernel.org>
Subject: Re: [PATCH v2 0/22] KVM: optimize for MMIO handled

On 06/22/2011 05:27 PM, Xiao Guangrong wrote:
> In this version, we fix the bugs in the v1:
> - fix broken read emulation spans a page boundary
> - fix invalid spte point is got if we walk shadow page table
>    out of the mmu lock
>
> And, we also introduce some rules to modify spte in this version,
> then it does not need to atomically clear/set spte on x86_32 host
> anymore, the performance report of x86_32 host is in the later section
>
> Avi,
>
> I have sampled the operation of lockless shadow page walking as below steps:
> - mark walk_shadow_page_get_mmio_spte as 'noinline'
> - do the netperf test, the client is on the guest(NIC is e1000) and the server
>    is on the host, it can generate large press of mmio access
> - using perf to sample it, and the result of 'perf report' is attached
>
> The ratio of walk_shadow_page_get_mmio_spte is 0.09%, the ratio of handle_ept_misconfig
> is 0.11%, the ratio of handle_mmio_page_fault_common is 0.07%
>
> I think it is acceptable, your opinion?
>

Yes.

The patchset scares me, but it is nice work!  Good optimization and good 
clean up.

-- 
error compiling committee.c: too many arguments to function

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