[Question] How to understand Clock-Pro algorithm?

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

Hi, every in LKML/linux-mm:

    I have been read CLOCK-Pro paper since last week, and am going to 
write one python demo.

    After just read , I think I can understand it, however once I begin 
implement it, I
found there are many point that not clear.
   
    First, two important parameters Mc, Mh,

    In that paper, it assume total memory size is M. (in number of page)
   
    There is a formula:
      
       M = Mc+Mh.
      
        Mc, number of cold pages in memory,
        Mh, number of hot pages in memory.
   
    So, in clock list, we can keep track 2M page metadatas at most, we 
may include M
non-resident pages.
      
    In '4.3 operationes on searching vicim pages' , the authors said

    "we keep track of the number of non-resident cold pages, 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."

    My question is out:As this paper words, the number of cold page is 
total of resident cold pages
and non-resident pages. It's the seem number of non-resident cold pages 
can not beyond M at all!
   
    I also have more questions on CLOCK-Pro. but this question is most 
doublt for me.

    Any clear word is welcome. thank in advanced.

    I suppose experience is more important than theory in 
page-replacement field, is it right?



liyu