🚀 go-pugleaf

lgy@newton.phys.washington.edu (Laurence Yaffe) writes:

>    A lot of current machines, such as my MIPS box, have pretty standard
>virtual memory systems: demand paging is used to allocate real memory to
>individual processes, with some sort of least-recently-used algorithm
>employed to select pages to write out.
>Severe, and unnecessary, performance degradation can occur if you have several
>processes which have very poor locality of reference when accessing their
>data, are sufficiently small that any singly process can fit in real memory,
>and yet sufficiently large that no two processes will fit in real memory.

To avoid excessive page fault rate, a good algorithm is to load in multiple
pages depending on system load.  Actually how many pages should you load in
is still a research question.  In HP's term, loading in extra pages is
called 'pre-fetching'.

HP's MPE/XL have pre-fetching.  I don't know about Unix, but my guess is
that Unix probably does not.


 -Thomas Wang ("I am, therefore I am."
                 - Akira               )

                                                     ttwang@polyslo.calpoly.edu