Re: [Question] How to understand Clock-Pro algorithm?

[liyu <liyu@ccoss.com.cn>]

Hi, All.
   
    In my words, pages in memory is either resident or non-resident.
In linux internal, mapped or unmapped.
   
    So number of non-resident pages is alway less than total number
of pages in memory.

    Is your pages physics pages? or, it is Logical pages?   However,
I think both is same here.

    Waitting for your answer.
   
    Thanks.


                                                 liyu


Song Jiang Wrote:

>On Mon, 2005-09-19 at 23:02, liyu wrote:
>
>  
>
>>    Let's assume Mn is the total number of non-resident pages in follow 
>>words.
>>
>>    Nod, 'M=Mh+Mc' and 'Mc+Mn' < 2M are always true.
>>
>>    Have this implied that Mn is alway less than M? I think so.
>>    
>>
>    Yes.
>
>  
>
>>    but if "Once the number exceeds M the memory size in number of pages,
>>we terminted the test period of the cold page pointed to by HAND-test."
>>
>>    If Mn is alway less than M, when we move to HAND-test?
>>    
>>
>
>The algorithm tries to ensure that Mn <= M holds. 
>Once Mn == M+1 is detected, run HAND-test to bring it
>back to Mn == M. That is, only during the transition period, 
>Mn <= M might not hold, and we make a correction quickly.
>
>So there is no contradiction here.
>   Song
>
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