Messages in this thread | | | Date | Thu, 27 Nov 2008 07:27:59 +0100 | From | Eric Dumazet <> | Subject | Re: [PATCH 0/6] fs: Scalability of sockets/pipes allocation/deallocation on SMP |
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Christoph Lameter a écrit : > On Thu, 27 Nov 2008, Eric Dumazet wrote: > >> The last point is about SLUB being hit hard, unless we >> use slub_min_order=3 at boot, or we use Christoph Lameter >> patch (struct file RCU optimizations) >> http://thread.gmane.org/gmane.linux.kernel/418615 >> >> If we boot machine with slub_min_order=3, SLUB overhead disappears. > > > I'd rather not be that drastic. Did you try increasing slub_min_objects > instead? Try 40-100. If we find the right number then we should update > the tuning to make sure that it pickes the right slab page sizes. > >
4096/192 = 21
with slub_min_objects=22 :
# cat /sys/kernel/slab/filp/order 1 # time ./socket8 real 0m1.725s user 0m0.685s sys 0m12.955s
with slub_min_objects=45 :
# cat /sys/kernel/slab/filp/order 2 # time ./socket8 real 0m1.652s user 0m0.694s sys 0m12.367s
with slub_min_objects=80 :
# cat /sys/kernel/slab/filp/order 3 # time ./socket8 real 0m1.642s user 0m0.719s sys 0m12.315s
I would say slub_min_objects=45 is the optimal value on 32bit arches to get acceptable performance on this workload (order=2 for filp kmem_cache)
Note : SLAB here is disastrous, but you already knew that :)
real 0m8.128s user 0m0.748s sys 1m3.467s
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