Re: shrink_mmap() change in ac-21

Rik van Riel
2000-06-19T22:10:00Z

On Mon, 19 Jun 2000, Jamie Lokier wrote:
> Zlatko Calusic wrote:
> > The shrink_mmap() change in your latest prepatch (ac12) doesn't look
> > very healthy. Removing the test for the wrong zone we effectively
> > discard lots of wrong pages before we get to the right one. That is
> > effectively flushing the page cache and we have unbalanced system.
>
> You know, there may be some sense in removing pages from the
> wrong zone, if those wrong zones are quite full.

If the zone is full, it can't be a "wrong zone". The problem
was that we kept removing pages from zones they shouldn't be
removed from. If a zone has zone->free_pages > zone->pages_high,
we should stop freeing pages from that zone.

> If the DMA zone desparately needs free pages and keeps needing
> them, isn't it good to encourage future non-DMA allocations to
> use another zone?

Ahh, but we already do this (up to zone->pages_high). It just
doesn't make sense to keep doing this infinitely ;)

Please wait a few more minutes for a patch which should fix it.
I've assembled a very conservative patch set, grabbing bits from
patches by Juan Quintela, Roger Larson and one minute snippet
from the old 2.3 code...

regards,

Rik
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