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authorDave Chinner <dchinner@redhat.com>2010-09-27 11:09:51 +1000
committerAlex Elder <aelder@sgi.com>2010-10-18 15:07:55 -0500
commit69b491c214d7fd4d4df972ae5377be99ca3753db (patch)
treeb0d022080d8da893e525ee6502878424cffbd8c2 /Documentation/fb/modedb.txt
parente3a20c0b02e1704ab115dfa9d012caf0fbc45ed0 (diff)
xfs: serialise inode reclaim within an AG
Memory reclaim via shrinkers has a terrible habit of having N+M concurrent shrinker executions (N = num CPUs, M = num kswapds) all trying to shrink the same cache. When the cache they are all working on is protected by a single spinlock, massive contention an slowdowns occur. Wrap the per-ag inode caches with a reclaim mutex to serialise reclaim access to the AG. This will block concurrent reclaim in each AG but still allow reclaim to scan multiple AGs concurrently. Allow shrinkers to move on to the next AG if it can't get the lock, and if we can't get any AG, then start blocking on locks. To prevent reclaimers from continually scanning the same inodes in each AG, add a cursor that tracks where the last reclaim got up to and start from that point on the next reclaim. This should avoid only ever scanning a small number of inodes at the satart of each AG and not making progress. If we have a non-shrinker based reclaim pass, ignore the cursor and reset it to zero once we are done. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Alex Elder <aelder@sgi.com>
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