lkml.org 
[lkml]   [2006]   [Jan]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [patch 3/4] net: Percpufy frequently used variables -- proto.sockets_allocated
    Ravikiran G Thirumalai a écrit :
    > Change the atomic_t sockets_allocated member of struct proto to a
    > per-cpu counter.
    >
    > Signed-off-by: Pravin B. Shelar <pravins@calsoftinc.com>
    > Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org>
    > Signed-off-by: Shai Fultheim <shai@scalex86.org>
    >
    Hi Ravikiran

    If I correctly read this patch, I think there is a scalability problem.

    On a big SMP machine, read_sockets_allocated() is going to be a real killer.

    Say we have 128 Opterons CPUS in a box.

    You'll need to bring 128 cache lines (plus 8*128 bytes to read the 128
    pointers inside percpu structure)

    I think a solution 'a la percpu_counter' is preferable, or even better a
    dedicated per_cpu with a threshold management (see mm/swap.c , function
    vm_acct_memory() to see how vm_committed_space is updated without too bad SMP
    scalability)

    Thank you

    Eric

    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2006-01-27 09:57    [W:0.037 / U:158.720 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site