Re: cp file /dev/zero <-> cache [was Re: increasing page size]

Rik van Riel (
Tue, 7 Jul 1998 18:00:29 +0200 (CEST)

On Tue, 7 Jul 1998, Stephen C. Tweedie wrote:

> > I have a better idea. The RSS for an inode shouldn't be
> > allowed to grow larger than 50% of the size of the page
> > cache when:
> Oh dear. More arbitrary rules in the VM --- just what we need! And
> if we have more than one file trying to consume all of cache, what
> then? Each one gets 50%, bang, the rule falls over. And the 25%
> memory rule --- we expect that to work on 8MB machines as well as
> 512MB?

Eurhmm, what I _meant_ to say was:

When a file consumes more than a certain percentage
of the page cache and the page cache is larger than
a certain percentage of memory, we must grab a page
from the page cache instead of getting a new page...

This will give the intended behaviour; the page cache
doesn't grow, the inode's RSS _can_ grow, but after
a certain point it will just start consuming it's own
pages (since the other non-busy pages have left the
cache long ago)...
(in DU the percentages are 10% and 50%, but I think
they should be 10% and 25% for Linux)

I think this might actually work :-) I'll code something
up this evening...

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