Messages in this thread | | | Date | Thu, 13 Dec 2012 10:34:20 +0000 | From | Mel Gorman <> | Subject | Re: [patch 2/8] mm: vmscan: disregard swappiness shortly before going OOM |
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On Wed, Dec 12, 2012 at 04:43:34PM -0500, Johannes Weiner wrote: > When a reclaim scanner is doing its final scan before giving up and > there is swap space available, pay no attention to swappiness > preference anymore. Just swap. > > Note that this change won't make too big of a difference for general > reclaim: anonymous pages are already force-scanned when there is only > very little file cache left, and there very likely isn't when the > reclaimer enters this final cycle. > > Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Ok, I see the motivation for your patch but is the block inside still wrong for what you want? After your patch the block looks like this
if (sc->priority || noswap) { scan >>= sc->priority; if (!scan && force_scan) scan = SWAP_CLUSTER_MAX; scan = div64_u64(scan * fraction[file], denominator); }
if sc->priority == 0 and swappiness==0 then you enter this block but fraction[0] for anonymous pages will also be 0 and because of the ordering of statements there, scan will be
scan = scan * 0 / denominator
so you are still not reclaiming anonymous pages in the swappiness=0 case. What did I miss?
-- Mel Gorman SUSE Labs
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