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    SubjectRe: [RFC PATCH 0/5] x86,smp: make ticket spinlock proportional backoff w/ auto tuning
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    On Wed, Jan 2, 2013 at 9:15 PM, Rik van Riel <riel@redhat.com> wrote:
    > The v2 series integrates several ideas from Michel Lespinasse
    > and Eric Dumazet, which should result in better throughput and
    > nicer behaviour in situations with contention on multiple locks.
    >
    > Please let me know if you manage to break this code in any way,
    > so I can fix it...

    I'm seeing some very weird things on my 3 test machines. Looks like
    the spinlock delay sometimes gets crazy, at which point spinlock
    performance becomes unbearable and the network driver freaks out.

    # ./spinlock_load_test
    1 spinlocks: 24159990
    2 spinlocks: 12900657
    3 spinlocks: 11547771
    4 spinlocks: 9113
    6 spinlocks: 259
    8 spinlocks: 310
    12 spinlocks: 283
    16 spinlocks:
    <seems to be stuck here; meanwhile my serial console fills up with
    network driver cries>

    Well, I take it as an incitation to pay special attention to this code review :)

    --
    Michel "Walken" Lespinasse
    A program is never fully debugged until the last user dies.


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