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    SubjectRe: [PATCH 0/6] fs: Scalability of sockets/pipes allocation/deallocation on SMP
    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)
    >> 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
    # time ./socket8
    real 0m1.725s
    user 0m0.685s
    sys 0m12.955s

    with slub_min_objects=45 :

    # cat /sys/kernel/slab/filp/order
    # time ./socket8
    real 0m1.652s
    user 0m0.694s
    sys 0m12.367s

    with slub_min_objects=80 :

    # cat /sys/kernel/slab/filp/order
    # 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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      Last update: 2008-11-27 07:31    [W:0.047 / U:8.556 seconds]
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