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authorAruna Ramakrishna <aruna.ramakrishna@oracle.com>2016-10-27 17:46:32 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-10-27 18:43:43 -0700
commit07a63c41fa1f6533f5668e5b33a295bfd63aa534 (patch)
treebaccc737b4c09ce0abdc4bb0209ab9eccb2f9612 /ipc
parent1f84a18fc010d7a62667199c9be35872bbf31526 (diff)
mm/slab: improve performance of gathering slabinfo stats
On large systems, when some slab caches grow to millions of objects (and many gigabytes), running 'cat /proc/slabinfo' can take up to 1-2 seconds. During this time, interrupts are disabled while walking the slab lists (slabs_full, slabs_partial, and slabs_free) for each node, and this sometimes causes timeouts in other drivers (for instance, Infiniband). This patch optimizes 'cat /proc/slabinfo' by maintaining a counter for total number of allocated slabs per node, per cache. This counter is updated when a slab is created or destroyed. This enables us to skip traversing the slabs_full list while gathering slabinfo statistics, and since slabs_full tends to be the biggest list when the cache is large, it results in a dramatic performance improvement. Getting slabinfo statistics now only requires walking the slabs_free and slabs_partial lists, and those lists are usually much smaller than slabs_full. We tested this after growing the dentry cache to 70GB, and the performance improved from 2s to 5ms. Link: http://lkml.kernel.org/r/1472517876-26814-1-git-send-email-aruna.ramakrishna@oracle.com Signed-off-by: Aruna Ramakrishna <aruna.ramakrishna@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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