On Fri, Jan 21, 2005 at 03:42:38PM +0100, Manfred Koizar wrote:
> On Fri, 21 Jan 2005 02:31:40 +0200, Hannu Krosing <[EMAIL PROTECTED]> wrote:
> >2) Another simple, but nondeterministic, hack would be using randomness,
> >i.e.
> >
> > 2.1) select a random buffer in LR side half (or 30% or 60%) of
> > for replacement.
> >
> > 2.2) dont last accessed pages to top of LRU list immediately,
> > just push them uphill some amount, either random, or
> > perhaps 1/2 the way to top at each access.
>
> Sounds good, but how do find the middle of a linked list? Or the other
> way round: Given a list element, how do you find out its position in a
> linked list? So the only approach that is easily implementable is
>
> 2.3) If a sequential scan hint flag is set, put the buffer into the
> free list at a random position.
>
If we use the clock algorithm as an approximation to LRU, we can avoid
a lot of the MRU/LRU churn. Then the seq. scan hint could just be another
type of clock bit.
Ken
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