Messages in this thread | | | Subject | Re: [PATCH v4 resend] mm/slab: Improve performance of gathering slabinfo stats | From | Aruna Ramakrishna <> | Date | Mon, 29 Aug 2016 17:48:25 -0700 |
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On 08/29/2016 05:44 PM, Aruna Ramakrishna wrote: > 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. > > Signed-off-by: Aruna Ramakrishna <aruna.ramakrishna@oracle.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> > Cc: Andrew Morton <akpm@linux-foundation.org> > --- > Note: this has been tested only on x86_64. >
This patch has spawned off a very interesting discussion in a older thread, and I guess the latest incarnation of this patch got buried. I'm resending it for review/approval.
Thanks, Aruna
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