At 14:26 8/21/95 -0400, Jonathan Shapiro wrote:
>The competition in question is competition for memory page frames.
>There are three operations I can think of that remove a page frame
>from the free list:
>
> 1. Migration (read I/O)
> 2. Pagein (read I/O)
> 3. Revivification (discovery that an "old" page is still being
> used).
>
>Contention between the first two sources can be eliminated if there
>are always enough allocatable free page frames to satisfy all
>outstanding read requests. This should be straightforward to enforce
>if we can deal with (3).
>
>The problem, then, is that revivification can reduce the number of
>allocatable frames below the number of outstanding read requests, with
>the effect that the read requests will be unable to make progress.
>
I confess to being confused. Under what circumstances does (3) come into play?
Bill