From: David Miller <davem@davemloft.net>
To: dada1@cosmosbay.com
Cc: andi@firstfloor.org, rick.jones2@hp.com,
shemminger@linux-foundation.org, netdev@vger.kernel.org
Subject: Re: bridge: faster compare for link local addresses
Date: Tue, 13 Mar 2007 12:39:54 -0700 (PDT) [thread overview]
Message-ID: <20070313.123954.21595557.davem@davemloft.net> (raw)
In-Reply-To: <200703131438.32570.dada1@cosmosbay.com>
From: Eric Dumazet <dada1@cosmosbay.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.
next prev parent reply other threads:[~2007-03-13 19:40 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-03-12 23:20 bridge: faster compare for link local addresses Stephen Hemminger
2007-03-12 23:26 ` David Miller
2007-03-13 0:05 ` Rick Jones
2007-03-13 0:10 ` David Miller
2007-03-13 14:01 ` Andi Kleen
2007-03-13 13:38 ` Eric Dumazet
2007-03-13 19:39 ` David Miller [this message]
2007-03-13 20:06 ` Stephen Hemminger
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