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From: Herbert Xu <herbert@gondor.apana.org.au>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>,
	netdev@vger.kernel.org, Roland Dreier <roland@purestorage.com>
Subject: Re: arp_hash
Date: Mon, 23 Mar 2015 09:51:04 +1100	[thread overview]
Message-ID: <20150322225104.GA8853@gondor.apana.org.au> (raw)
In-Reply-To: <20150322215612.GA8274@gondor.apana.org.au>

On Mon, Mar 23, 2015 at 08:56:12AM +1100, Herbert Xu wrote:
> On Sun, Mar 22, 2015 at 05:56:21AM -0700, Eric Dumazet wrote:
> > On Sun, 2015-03-22 at 22:42 +1100, Herbert Xu wrote:
> > > 
> > > While googling I found the 2011 discussion on changing the arp_hash
> > > function.  I must say that I'm not really impressed by the new
> > > function that replaced jhash :)
> > > 
> > > 	u32 key = *(const u32 *)pkey;
> > > 	u32 val = key ^ hash32_ptr(dev);
> > > 
> > > 	return val * hash_rnd[0];
> 
> In fact this function is worse than I thought.  Because the IP

OK I'm wrong because net/core/neighbour.c uses only the high-order
bits of the hash.

Sorry for the noise.
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

  reply	other threads:[~2015-03-22 22:51 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-22 11:42 arp_hash Herbert Xu
2015-03-22 12:56 ` arp_hash Eric Dumazet
2015-03-22 16:57   ` arp_hash David Miller
2015-03-22 21:21   ` arp_hash Herbert Xu
2015-03-22 21:56   ` arp_hash Herbert Xu
2015-03-22 22:51     ` Herbert Xu [this message]
2015-03-22 23:22       ` arp_hash Herbert Xu
2015-03-22 23:35         ` arp_hash Herbert Xu
2015-03-23 10:58           ` arp_hash Herbert Xu
2015-03-22 22:58     ` arp_hash David Miller
2015-03-22 23:08       ` arp_hash Herbert Xu
2015-03-22 23:50         ` arp_hash David Miller
2015-03-22 23:53           ` arp_hash Herbert Xu
2015-03-22 16:54 ` arp_hash David Miller
2015-03-22 21:34   ` arp_hash Herbert Xu
2015-03-22 22:57     ` arp_hash David Miller
2015-03-22 23:42       ` arp_hash Herbert Xu
2015-03-22 23:53         ` arp_hash David Miller
2015-03-23 11:01           ` arp_hash Herbert Xu

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