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

Stephen C. Tweedie (sct@redhat.com)
Tue, 7 Jul 1998 13:35:46 +0100


Hi,

On 06 Jul 1998 08:37:02 -0500, ebiederm+eric@npwt.net (Eric
W. Biederman) said:

> The use of touch_page and age_page appear to be the most likely
> canidates for the page cache being more persistent than it used to
> be.

Yes., very much so.

> If I'm not mistaken shrink_mmap must be called more often now to
> remove a given page.

Indeed. Three things I think we need to do are to lower the age
ceiling for the page cache pages; perform page allocations for the
page cache with a GFP_CACHE flag which forces us to look for other
cache pages first in try_to_free_page; and try to eliminate several
pages at a time from the page cache when we can. (There's no point in
keeping only half the pages from a closed, sequentially accessed file
in cache.)

The first two of these are definitely small enough and clean enough
changes to be appropriate for 2.1.

--Stephen

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