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From: "Brian F. G. Bidulock" <bidulock@openss7.org>
To: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Cc: David Miller <davem@davemloft.net>,
	draghuram@rocketmail.com, linux-kernel@vger.kernel.org,
	netdev@vger.kernel.org
Subject: Re: Question about tcp hash function tcp_hashfn()
Date: Thu, 1 Jun 2006 01:11:25 -0600	[thread overview]
Message-ID: <20060601011125.C22283@openss7.org> (raw)
In-Reply-To: <20060601070136.GA754@2ka.mipt.ru>; from johnpol@2ka.mipt.ru on Thu, Jun 01, 2006 at 11:01:36AM +0400

Evgeniy,

On Thu, 01 Jun 2006, Evgeniy Polyakov wrote:

> On Thu, Jun 01, 2006 at 12:46:08AM -0600, Brian F. G. Bidulock (bidulock@openss7.org) wrote:
> > > Since pseudo-randomness affects both folded and not folded hash
> > > distribution, it can not end up in different results.
> > 
> > Yes it would, so to rule out pseudo-random effects the pseudo-
> > random number generator must be removed.
> > 
> > > 
> > > You are right that having test with 2^48 values is really interesting,
> > > but it will take ages on my test machine :)
> > 
> > Try a usable subset; no pseudo-random number generator.
> 
> I've run it for 2^30 - the same result: folded and not folded Jenkins
> hash behave the same and still both results produce exactly the same
> artifacts compared to XOR hash.

But not without the pseudo-random number generation... ?

> 
> Btw, XOR hash, as completely stateless, can be used to show how
> Linux pseudo-random generator works for given subset - it's average of
> distribution is very good.

But its distribution might auto-correlate with the Jenkins function.
The only way to be sure is to remove the pseudo-random number generator.

Just try incrementing from, say, 10.0.0.0:10000 up, resetting port number
to 10000 at 16000, and just incrementing the IP address when the port
number wraps, instead of pseudo-random, through 2^30 loops for both.
If the same artifacts emerge, I give in.

Can you show the same artifacts for jenkins_3word?


  reply	other threads:[~2006-06-01  7:11 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-05-31  4:29 Question about tcp hash function tcp_hashfn() Raghuram
2006-05-31  5:55 ` Brian F. G. Bidulock
2006-05-31  7:10   ` David Miller
2006-05-31  7:45     ` Brian F. G. Bidulock
2006-05-31  7:49       ` David Miller
2006-05-31  8:00         ` Brian F. G. Bidulock
2006-05-31  9:03           ` Evgeniy Polyakov
2006-05-31  9:12             ` David Miller
2006-05-31  9:44               ` Evgeniy Polyakov
2006-05-31  9:51             ` Brian F. G. Bidulock
2006-05-31 10:58               ` Evgeniy Polyakov
2006-05-31 11:04                 ` Evgeniy Polyakov
2006-05-31 13:06                   ` Evgeniy Polyakov
2006-05-31 18:29                     ` Brian F. G. Bidulock
2006-06-01  6:12                       ` Evgeniy Polyakov
2006-06-01  6:18                         ` David Miller
2006-06-01  6:22                           ` Brian F. G. Bidulock
2006-06-01  6:24                             ` David Miller
2006-05-31 18:41                 ` David Miller
2006-06-01  6:04                   ` Evgeniy Polyakov
2006-06-01  6:18                     ` Brian F. G. Bidulock
2006-06-01  6:30                       ` Evgeniy Polyakov
2006-06-01  6:46                         ` Brian F. G. Bidulock
2006-06-01  7:01                           ` Evgeniy Polyakov
2006-06-01  7:11                             ` Brian F. G. Bidulock [this message]
2006-06-01  8:38                               ` Evgeniy Polyakov
2006-06-01 10:24                                 ` Brian F. G. Bidulock
2006-06-01 11:06                                   ` Evgeniy Polyakov
2006-06-01 18:40                                     ` Brian F. G. Bidulock
2006-06-01 20:21                                       ` David Miller
2006-06-02  7:01                                       ` Evgeniy Polyakov
2006-06-02  5:40                     ` Florian Weimer
2006-06-02  7:48                       ` Evgeniy Polyakov
2006-06-02 15:10                         ` Brian F. G. Bidulock
2006-06-02 17:26                         ` Florian Weimer
2006-06-02 17:37                           ` Brian F. G. Bidulock
2006-05-31  9:52             ` Brian F. G. Bidulock
2006-05-31  8:49         ` Brian F. G. Bidulock
2006-05-31  9:02           ` David Miller
2006-05-31  9:39             ` Brian F. G. Bidulock

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