From: Florian Westphal <fw@strlen.de>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Florian Westphal <fw@strlen.de>, Changli Gao <xiaosuo@gmail.com>,
Patrick McHardy <kaber@trash.net>,
netfilter-devel@vger.kernel.org
Subject: Re: [PATCH] netfilter: remove modulo operations
Date: Sun, 24 Oct 2010 22:44:12 +0200 [thread overview]
Message-ID: <20101024204412.GN15247@Chamillionaire.breakpoint.cc> (raw)
In-Reply-To: <1287947511.2658.1678.camel@edumazet-laptop>
Eric Dumazet <eric.dumazet@gmail.com> wrote:
> Le dimanche 24 octobre 2010 à 20:25 +0200, Florian Westphal a écrit :
> > I'd imagine that the result of ((hash * total) >> 32) is (almost)
> > always zero, especially if total is small (which it is usually).
> >
>
> Absolutely not. total is a 32bit number, using full range.
>
> > Did you test that this change does not affect distribution average?
>
> That would be shocking actually, given we use jhash()
>
> I did same tricks in various parts of network stack in the past, and its
> fine.
Yes, you are right. I tested this change and it is OK.
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next prev parent reply other threads:[~2010-10-24 20:44 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-24 3:40 [PATCH] netfilter: remove modulo operations Changli Gao
2010-10-24 18:25 ` Florian Westphal
2010-10-24 19:11 ` Eric Dumazet
2010-10-24 20:44 ` Florian Westphal [this message]
2010-10-24 21:49 ` Maciej Żenczykowski
2010-10-25 3:02 ` Jan Engelhardt
2010-10-25 3:19 ` Maciej Żenczykowski
2010-10-25 9:13 ` Jan Engelhardt
2010-10-25 9:28 ` Jan Engelhardt
2010-10-25 9:26 ` Eric Dumazet
2010-10-25 15:39 ` Patrick McHardy
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