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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=476266FF.4080300@trash.net \
--to=kaber@trash.net \
--cc=dada1@cosmosbay.com \
--cc=netdev@vger.kernel.org \
--cc=netfilter-devel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).