From: David Miller <davem@davemloft.net>
To: florz@florz.de
Cc: mostrows@earthlink.net, netdev@vger.kernel.org
Subject: Re: [RESEND][PATCH 1/3] PPPoE: improved hashing routine
Date: Tue, 31 Jul 2007 01:26:09 -0700 (PDT) [thread overview]
Message-ID: <20070731.012609.41193630.davem@davemloft.net> (raw)
In-Reply-To: <20070731080719.GA12071@florz.florz.dyndns.org>
From: Florian Zumbiehl <florz@florz.de>
Date: Tue, 31 Jul 2007 10:07:19 +0200
> Erm, I'd say this not only produces different results than the old
> version, but it also produces "wrong" results, in that it ignores quite
> a bit of the data that's supposed to be hashed. If I didn't overlook
> something, it only considers addr&0x0f0f0f0f0f00 and sid&0x0f0f, given
> the right endianness of addr and that PPPOE_HASH_SIZE stays 16.
You're right, I need to fix the shifts up. How does this version
look?
hash ^= (hash >> 4) ^ (hash >> 12) ^ (hash >> 20);
return (head ^ (hash >> 8) ^ (hash >> 24)) &
(PPPOE_HASH_SIZE - 1);
Actually it might be simpler and more efficient to just make
PPPOE_HASH_SHIFT be 8.
next prev parent reply other threads:[~2007-07-31 8:26 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-29 6:04 [RESEND][PATCH 1/3] PPPoE: improved hashing routine Florian Zumbiehl
2007-07-31 0:47 ` David Miller
2007-07-31 8:07 ` Florian Zumbiehl
2007-07-31 8:26 ` David Miller [this message]
2007-07-31 9:01 ` Florian Zumbiehl
2007-07-31 9:16 ` David Miller
2007-07-31 11:05 ` Florian Zumbiehl
2007-07-31 20:51 ` David Miller
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