linux-kernel - Re: [PATCH 5/6] KVM MMU: reduce kvm_mmu

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Date:	Mon, 12 Apr 2010 19:11:44 +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 5/6] KVM MMU: reduce kvm_mmu_page size



Avi Kivity wrote:
> On 04/12/2010 11:05 AM, Xiao Guangrong wrote:
>> 'multimapped' and 'unsync' in 'struct kvm_mmu_page' are just indication
>> field, we can use flag bits instand of them
>>
>> @@ -202,9 +202,10 @@ struct kvm_mmu_page {
>>        * in this shadow page.
>>        */
>>       DECLARE_BITMAP(slot_bitmap, KVM_MEMORY_SLOTS +
>> KVM_PRIVATE_MEM_SLOTS);
>> -    int multimapped;         /* More than one parent_pte? */
>>       int root_count;          /* Currently serving as active root */
>> -    bool unsync;
>> +    #define MMU_PAGE_MULTIMAPPED 0x1        /* More than one
>> parent_pte? */
>> +    #define MMU_PAGE_UNSYNC 0x2
>> +    unsigned int flags;
>>       unsigned int unsync_children;
>>       union {
>>    
> 
> Please just use bool for multimapped.  If we grow more than 4 flags, we
> can use 'bool flag : 1;' to reduce space while retaining readability.
> 

Yeah, good idea, i'll fix it in the next version

Thanks,
Xiao
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