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Date: Sat, 21 Apr 2012 12:36:21 +0800
From: Xiao Guangrong <xiaoguangrong.eric@gmail.com>
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To: Takuya Yoshikawa <takuya.yoshikawa@gmail.com>
CC: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>,
        Avi Kivity <avi@redhat.com>, Marcelo Tosatti <mtosatti@redhat.com>,
        LKML <linux-kernel@vger.kernel.org>, KVM <kvm@vger.kernel.org>
Subject: Re: [PATCH v2 07/16] KVM: MMU: introduce for_each_pte_list_spte
References: <4F87FA69.5060106@linux.vnet.ibm.com> <4F87FC19.8080404@linux.vnet.ibm.com> <20120414114422.e3fe6e2abbfdcce61e6f69c8@gmail.com> <4F8B93B9.2030801@linux.vnet.ibm.com> <20120417234731.a19f270d5701b11ce95d13d4@gmail.com> <4F8E3C7F.5040601@linux.vnet.ibm.com> <20120421100113.4040ac700af6d2b04dda613f@gmail.com>
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On 04/21/2012 09:01 AM, Takuya Yoshikawa wrote:

> Sorry for the delay.
> 
> On Wed, 18 Apr 2012 12:01:03 +0800
> Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> wrote:
> 
>>> I have checked dirty-log-perf myself with this patch [01-07].
>>>
>>> GET_DIRTY_LOG for 1GB dirty pages has become more than 15% slower.
> 
>> Thanks for your test!
>>
>> Unbelievable, i will do more test and check it more carefully.
> 
> GET_DIRTY_LOG now traverses rmap lists intensively.
> So only a small change can affect the performance when there are many
> dirty pages.
> 
>> Could you please open your tool, then i can reproduction it and find the
>> real reason?
> 
> It's already in kvm unit tests!
> 


Great, i will check that.

>> I will check whether your tool is better then kernbench/autotest after
>> review your tool.
> 
> Let's focus on "lock-less" now: so dirty-log-perf is not needed now.
> 
> I think you failed to appeal the real advantage of your "lock-less" approach!
> I will write about this on v3-threads.


Thank you very much, Takuya!