From: Sven Eckelmann <sven@narfation.org>
To: b.a.t.m.a.n@lists.open-mesh.org
Subject: Re: [B.A.T.M.A.N.] [PATCH 1/5] batman-adv: Use common Jenkins Hash implementation
Date: Mon, 26 Nov 2012 10:40:07 +0100 [thread overview]
Message-ID: <2094937.nutMCHjP7e@bentobox> (raw)
In-Reply-To: <20121126093309.GB22729@ritirata.org>
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On Monday 26 November 2012 10:33:09 Antonio Quartulli wrote:
> On Sun, Nov 25, 2012 at 07:23:27PM +0100, Sven Eckelmann wrote:
> > An unoptimized version of the Jenkins one-at-a-time hash function is
> > copied all over the code wherever an hashtable is used. Instead the
> > optimized version shared between the whole kernel should be used to
> > reduce code duplication and keep bugs at a single point.
> >
> > Only the TT and DAT code must use the old implementation to guarantee the
> > same distribution of the elements in the hash. The TT code needs it
> > because the CRC exchanged between the mesh nodes is computed over the
> > entries in the hash.
> Hi Sven,
>
> I don't fully get why we can't use this new implementation in TT. What's
> wrong with the CRC computation?
The in kernel implementation will create a different hash sum -> tt entries
will end up in a different bucket -> CRC will be different (please correct me
about the last step... just had this problem in the back of my head).
Kind regards,
Sven
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next prev parent reply other threads:[~2012-11-26 9:40 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-25 18:23 [B.A.T.M.A.N.] [PATCH 1/5] batman-adv: Use common Jenkins Hash implementation Sven Eckelmann
2012-11-25 18:23 ` [B.A.T.M.A.N.] [PATCH 2/5] batman-adv: Define the size of hashtables by hash bits Sven Eckelmann
2012-11-25 18:23 ` [B.A.T.M.A.N.] [PATCH 3/5] batman-adv: Remove size information from hash table Sven Eckelmann
2012-11-25 18:23 ` [B.A.T.M.A.N.] [PATCH 4/5] batman-adv: Remove wrapper structure for hash tables Sven Eckelmann
2012-11-25 18:23 ` [B.A.T.M.A.N.] [PATCH 5/5] batman-adv: Allow to use different sized hash locks array Sven Eckelmann
2012-11-26 9:33 ` [B.A.T.M.A.N.] [PATCH 1/5] batman-adv: Use common Jenkins Hash implementation Antonio Quartulli
2012-11-26 9:40 ` Sven Eckelmann [this message]
2012-11-26 10:10 ` Sven Eckelmann
2012-11-26 12:30 ` Antonio Quartulli
2012-11-26 12:39 ` Sven Eckelmann
2012-11-26 12:46 ` Antonio Quartulli
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