Subject: Re: [PATCH next-next-2.6] netdev: better dev_name_hash

From: Hagen Paul Pfeifer <[email-masked]>
Date: Sun, 25 Oct 2009 21:17:14 +0100

* Octavian Purdila | 2009-10-25 21:58:53 [+0200]:

>
>The current dev_name_hash is not very good at spreading entries when a
>large number of interfaces of the same type (e.g. ethXXXXX) are used.
>
>Here are some performance numbers for creating 16000 dummy interfaces with
>and without the patch (with per device sysctl entries disabled)
>
>    With patch                      Without patch
>
>    real    0m 2.27s                real    0m 4.32s
>    user    0m 0.00s                user    0m 0.00s
>    sys     0m 1.13s                sys     0m 2.16s

Can you rerun the test with jhash() as the hash function? Just for clearness -
the spreading of jhash should be more uniformly distributed. At the end: where
is the threshold where a more accurate hash function is superior.

HGN

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