Re: unexpected paging during large file reads in 2.1.127

Rik van Riel (H.H.vanRiel@phys.uu.nl)
Thu, 12 Nov 1998 14:39:53 +0100 (CET)

On 12 Nov 1998, Zlatko Calusic wrote:
> "David J. Fred" <djf@ic.net> writes:
>
> > Summary: When doing large file reads from disk the system pages
> > unexpectedly causing moderate to severe degradation in I/O
> > and overall system performance even though there is plenty of
> > memory.
>
> Page cache is definitely too aggressive on recent kernels. I
> developed a small patch that avoids excessive swapouts. It helps
> kswapd to have less trouble reusing pages from page cache.

Agreed, we should do something about that.

> + age_page(page);
> + age_page(page);
> age_page(page);

Do I hear "priority paging"? :))

> count_max = (limit<<2) >> (priority>>1);
> count_min = (limit<<2) >> (priority);

Maybe increasing these has the same effect but with
the advantage of keeping page aging intact.

cheers,

Rik -- slowly getting used to dvorak kbd layout...
+-------------------------------------------------------------------+
| Linux memory management tour guide. H.H.vanRiel@phys.uu.nl |
| Scouting Vries cubscout leader. http://www.phys.uu.nl/~riel/ |
+-------------------------------------------------------------------+

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/