Re: Page replacement algorithm in buffer cache

>
>> I think that if the initialization of USAGE_COUNT starts at the maximum
>> allowed value instead of one, we can have a better solution to this
>> problem.
>
> So what is your idea, if you start at maximum, what we will do for further
> accesses to it?

I havent chalked out a detailed plan yet, but I think the idea of
initializing USAGE_COUNT to maximum value is not at all good. I was
just thinking off the top of my head.

> Why do you want to give more priority to just loaded page?

I just want it to have more chances to stay, rather than being
replaced pretty early. This is because, as I said earlier, a new page
could be in high demand in near future, which would lead to repeated
replacement-bringing in of page and hence cause overheads.

>> Another,more complex solution could be to introduce an aging factor

This is the one I think would work out best, add an age factor as to
the time duration which an entry has spent in the cache along with its
usage count.

So, what I am proposing here is to add another factor in the
clocksweep algorithm when it selects victim pages for replacement.
Specifically, the selection of victim pages should be done with the
usage_count AND the time spent by the entry in the cache. This would
give priority to pages with high accesses and not ignore relatively
young pages as well. If a page is not accessed for a long time after
it was allocated, it would be the ideal victim for replacement both in
terms of USAGE_COUNT as well as age.

Regards,

Atri

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Regards,

Atri
l'apprenant