Thread (32 messages) 32 messages, 10 authors, 2011-11-11

Re: [rfc 3/3] mm: vmscan: revert file list boost on lru addition

From: KAMEZAWA Hiroyuki <hidden>
Date: 2011-11-07 02:46:27
Also in: lkml

On Wed, 2 Nov 2011 17:32:47 +0100
Johannes Weiner [off-list ref] wrote:
The idea in 9ff473b 'vmscan: evict streaming IO first' was to steer
reclaim focus onto file pages with every new file page that hits the
lru list, so that an influx of used-once file pages does not lead to
swapping of anonymous pages.

The problem is that nobody is fixing up the balance if the pages in
fact become part of the resident set.

Anonymous page creation is neutral to the inter-lru balance, so even a
comparably tiny number of heavily used file pages tip the balance in
favor of the file list.

In addition, there is no refault detection, and every refault will
bias the balance even more.  A thrashing file working set will be
mistaken for a very lucrative source of reclaimable pages.

As anonymous pages are no longer swapped above a certain priority
level, this mechanism is no longer needed.  Used-once file pages
should get reclaimed before the VM even considers swapping.

Signed-off-by: Johannes Weiner <redacted>
Do you have some results ?

Thanks,
-Kame

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