linux-kernel - Re: [RFC][PATCH] KVM: perf: a smart tool to analyse kvm events

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Message-ID: <4F14DD63.3010901@linux.vnet.ibm.com>
Date:	Tue, 17 Jan 2012 10:30:59 +0800
From:	Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>
To:	Avi Kivity <avi@...hat.com>
CC:	Marcelo Tosatti <mtosatti@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>, KVM <kvm@...r.kernel.org>
Subject: Re: [RFC][PATCH] KVM: perf: a smart tool to analyse kvm events

On 01/16/2012 06:11 PM, Avi Kivity wrote:


>> Total Samples:975981, Total events handled time:126502464.88us.
> 
> Nice!  If we can have a live version as well, this can replace kvm_stat.
> 
> The average numbers are really high.  Like a factor of 3x-4x off.  Would
> be good to print the standard deviation and see why.  Maybe it's due to
> the tracing overhead.
> 


It is a good suggestion, i will print stddev in the next version.

>> The default event to be analysed is vmexit, we can use --event to specify it,
>> for example, if we want to trace mmio event:
>> # ./perf kvm-events report --event mmio
>>   Warning: Error: expected type 5 but read 4
>>   Warning: Error: expected type 5 but read 0
>>   Warning: unknown op '}'
>>
>>
>> Analyze events for all VCPUs:
>>
>>          MMIO Access    Samples      Samples%         Time%        Avg time
>>
>>         0xfee00380:W     196589        64.95%        70.01%         3.83us
>>         0xfee00310:W      35356        11.68%         6.48%         1.97us
>>         0xfee00300:W      35356        11.68%        16.37%         4.97us
>>         0xfee00300:R      35356        11.68%         7.14%         2.17us
> 
> These are more reasonable (though still high - 5us for an ICR write?)
> 


Hmm, maybe i need look into it...

>> Total Samples:975981, Total events handled time:126502464.88us.
>>
>> I hope guys will like it and any comments are welcome! :)
> 
> I think it's great!  A live version would be a nice addition too.
> 
> Please copy the perf userspace maintainers to get more detailed review
> in the next version.
> 


Okay, Thanks!

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