netdev - Re: bridge: faster compare for link local addresses

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Date:	Tue, 13 Mar 2007 12:39:54 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	dada1@...mosbay.com
Cc:	andi@...stfloor.org, rick.jones2@...com,
	shemminger@...ux-foundation.org, netdev@...r.kernel.org
Subject: Re: bridge: faster compare for link local addresses

From: Eric Dumazet <dada1@...mosbay.com>
Date: Tue, 13 Mar 2007 14:38:32 +0100

> But memcmp() has a strong semantic (in libc). memcmp(a, b, 6) should
> do 6 byte compares and conditional branches, regardless of a/b
> alignment.  Or use the x86 "rep cmpsb" instruction that basically
> has the same cost.

Yep, that's the issue, gcc won't make the reductions necessary
here to get it down to one comparison and one branch.
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