Message-ID: <4FA6460C.8020702@redhat.com>
Date: Sun, 06 May 2012 12:36:12 +0300
From: Avi Kivity <avi@redhat.com>
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To: Marcelo Tosatti <mtosatti@redhat.com>
CC: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>,
        LKML <linux-kernel@vger.kernel.org>, KVM <kvm@vger.kernel.org>
Subject: Re: [PATCH v4 06/10] KVM: MMU: fast path of handling guest page fault
References: <4F9776D2.7020506@linux.vnet.ibm.com> <4F9777A4.208@linux.vnet.ibm.com> <20120426234535.GA5057@amt.cnet> <4F9A3445.2060305@linux.vnet.ibm.com> <20120427145213.GB28796@amt.cnet> <4F9B89D9.9060307@linux.vnet.ibm.com> <20120501013459.GB10142@amt.cnet> <4FA0C607.5010002@linux.vnet.ibm.com> <20120502210701.GA12604@amt.cnet> <4FA26B6E.408@linux.vnet.ibm.com> <20120505140836.GC11842@amt.cnet>
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On 05/05/2012 05:08 PM, Marcelo Tosatti wrote:
> It would be better if all these complications introduced by lockless
> updates can be avoided, say using A/D bits as Avi suggested.

Note that using A/D bits introduces new tradeoffs (when just a few bits
are dirtied per iteration, we reduce guest overhead, but increase host
overhead, since it has to scan a large number of sptes), and also a
large fraction of deployed systems don't have A/D bits support.  But it
should affect our thinking - since in the long term all hosts will have it.

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

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