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    SubjectRe: [PATCH] improved locking performance in rt_run_flush()
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    From: Dave Johnson <djohnson+linux-kernel@sw.starentnetworks.com>
    Date: Sat, 12 May 2007 12:36:47 -0400

    >
    > While testing adding/deleting large numbers of interfaces, I found
    > rt_run_flush() was the #1 cpu user in a kernel profile by far.
    >
    > The below patch changes rt_run_flush() to only take each spinlock
    > protecting the rt_hash_table once instead of taking a spinlock for
    > every hash table bucket (and ending up taking the same small set
    > of locks over and over).
    >
    > Deleting 256 interfaces on a 4-way SMP system with 16K buckets reduced
    > overall cpu-time more than 50% and reduced wall-time about 33%. I
    > suspect systems with large amounts of memory (and more buckets) will
    > see an even greater benefit.
    >
    > Note there is a small change in that rt_free() is called while the
    > lock is held where before it was called without the lock held. I
    > don't think this should be an issue.
    >
    > Signed-off-by: Dave Johnson <djohnson+linux-kernel@sw.starentnetworks.com>

    Thanks for this patch.

    I'm not ignoring it I'm just trying to brainstorm whether there
    is a better way to resolve this inefficiency. :-)
    -
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