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

Song Jiang
2005-09-20T05:16:45Z

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

>