linux-kernel - Re: [PATCH 4/4] KVM MMU: do not intercept invlpg if 'oos

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Date:	Wed, 05 May 2010 20:54:26 +0800
From:	Xiao Guangrong <xiaoguangrong@...fujitsu.com>
To:	Avi Kivity <avi@...hat.com>
CC:	Marcelo Tosatti <mtosatti@...hat.com>,
	KVM list <kvm@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/4] KVM MMU: do not intercept invlpg if 'oos_shadow'
 is disabled



Avi Kivity wrote:
> On 04/30/2010 12:05 PM, Xiao Guangrong wrote:
>> If 'oos_shadow' == 0, intercepting invlpg command is really
>> unnecessary.
>>
>> And it's good for us to compare the performance between enable
>> 'oos_shadow'
>> and disable 'oos_shadow'
>>
>> @@ -74,8 +74,9 @@ static int dbg = 0;
>>   module_param(dbg, bool, 0644);
>>   #endif
>>
>> -static int oos_shadow = 1;
>> +int __read_mostly oos_shadow = 1;
>>   module_param(oos_shadow, bool, 0644);
>> +EXPORT_SYMBOL_GPL(oos_shadow);
>>    
> 
> Please rename to kvm_oos_shadow to reduce potential for conflict with
> other global names.
> 
> But really, this is a debug option, I don't expect people to run with
> oos_shadow=0, so there's not much motivation to optimize it.

Agreed, but, 'oos_shadow' option is document in Documentation/kernel-parameters.txt,
if it's just a debug option, i think we do better not document it.

Thanks,
Xiao

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