From: Patrick McHardy <kaber@trash.net>
To: Eric Dumazet <dada1@cosmosbay.com>
Cc: netfilter-devel@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: [NETFILTER] xt_hashlimit : speedups hash_dst()
Date: Fri, 14 Dec 2007 12:20:31 +0100 [thread overview]
Message-ID: <476266FF.4080300@trash.net> (raw)
In-Reply-To: <4762646B.30207@cosmosbay.com>
Eric Dumazet wrote:
> 1) Using jhash2() instead of jhash() is a litle bit faster if applicable.
>
> 2) Thanks to jhash, hash value uses full 32 bits.
> Instead of returning hash % size (implying a divide)
> we return the high 32 bits of the (hash * size) that will
> give results between [0 and size-1] and same hash distribution.
>
> On most cpus, a multiply is less expensive than a divide, by an order
> of magnitude.
Clever :) Applied, thanks Eric.
next prev parent reply other threads:[~2007-12-14 11:20 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-12-14 11:09 [NETFILTER] xt_hashlimit : speedups hash_dst() Eric Dumazet
2007-12-14 11:20 ` Patrick McHardy [this message]
2007-12-14 18:30 ` David Miller
2007-12-14 20:59 ` Jarek Poplawski
2007-12-14 21:37 ` Eric Dumazet
2007-12-15 10:41 ` Jarek Poplawski
2007-12-15 11:04 ` Eric Dumazet
2007-12-16 5:42 ` David Miller
2007-12-17 12:38 ` Patrick McHardy
2007-12-17 14:04 ` Sami Farin
2007-12-17 14:15 ` Patrick McHardy
2007-12-14 21:40 ` Jarek Poplawski
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