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    SubjectRe: [PATCH 05/15] RDS: increase size of hash-table to 8K
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    Hi Dave,

    On 9/21/2015 4:55 PM, santosh shilimkar wrote:
    > On 9/21/2015 4:05 PM, David Miller wrote:
    >> From: Santosh Shilimkar <santosh.shilimkar@oracle.com>
    >> Date: Sat, 19 Sep 2015 19:04:42 -0400
    >>
    >>> Even with per bucket locking scheme, in a massive parallel
    >>> system with active rds sockets which could be in excess of multiple
    >>> of 10K, rds_bin_lookup() workload is siginificant because of smaller
    >>> hashtable size.
    >>>
    >>> With some tests, it was found that we get modest but still nice
    >>> reduction in rds_bind_lookup with bigger bucket.
    >>>
    >>> Hashtable Baseline(1k) Delta
    >>> 2048: 8.28% -2.45%
    >>> 4096: 8.28% -4.60%
    >>> 8192: 8.28% -6.46%
    >>> 16384: 8.28% -6.75%
    >>>
    >>> Based on the data, we set 8K as the bind hash-table size.
    >>>
    >>> Signed-off-by: Santosh Shilimkar <ssantosh@kernel.org>
    >>> Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
    >>
    >> Like others I would strongly prefer that you use a dynamically sized
    >> hash table.
    >>
    >> Eating 8k just because a module just happened to get loaded is really
    >> not appropriate.
    >>
    >> And there are many other places that use such a scheme, one example is
    >> the AF_NETLINK socket hash table.
    >
    > OK. Thanks for AF_NETLINK pointer. I will look it up.
    >
    I will follow your advice on resizable hash table usage. It seems
    to be neat and fits well. But I want to make sure that the
    implementation works for all the workloads so it will take
    some time. Hopefully I can get that ready with testing for 4.5.

    So for now,lets just drop the $subject patch from this
    series. Do you want me to resend the series with the $subject
    patch dropped, or you can apply rest of the series except
    this one.

    Let me know. Thanks !!

    Regards,
    Santosh





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