Re: journaling & VM

Hans Reiser
2000-06-07T21:52:10Z

Let me convey an aspect of its rightness.

Caches have a declining marginal utility. It is a good idea to keep at least a
little bit of each cache around. The classic problem is when you switch usage
patterns back and forth, and one of the caches has been completely flushed by,
say, a large file read. If just 3% of the amount of cache remained from when it
was being used that 3% might give you a lot of speedup when the usage pattern
flipped back.

Hans

Rik van Riel wrote:
>
> On Wed, 7 Jun 2000, Hans Reiser wrote:
>
> > The new age one 64th of your objects scheme causes pressure to
> > be proportional.....
>
> Which is wrong, unless the oldest pages from each zone happen
> to be the same age ;)
>
> Suppose a 5MB SHM segment gets deattached and not used for a
> long time. In this situation it makes little sense to round-robin
> free from the different caches if the other caches are under more
> pressure.
>
> > I am looking forward to reading the new 2.4 mm code during my
> > next aeroflot experience this sunday....
>
> I'm working on it, but I can't promise to have all of the
> active/inactive/scavenge list framework ready by then ;)
>
> regards,
>
> Rik
> --
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>
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