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Date: Thu, 6 Nov 2014 13:57:23 +0000
From: Bruce Richardson <bruce.richardson@intel.com>
To: Thomas Monjalon <thomas.monjalon@6wind.com>
Message-ID: <20141106135723.GA7252@bricha3-MOBL3>
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Cc: dev@dpdk.org, jigsaw <jigsaw@gmail.com>
Subject: Re: [dpdk-dev] [PATCH] Add user defined tag calculation callback to
 librte_distributor.
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On Thu, Nov 06, 2014 at 11:36:09AM +0100, Thomas Monjalon wrote:
> 2014-11-06 09:22, Bruce Richardson:
> > On Wed, Nov 05, 2014 at 07:24:13PM +0200, jigsaw wrote:
> > > http://dpdk.org/browse/dpdk/tree/lib/librte_distributor/rte_distributor.c#n285
> > > 
> > >         new_tag = (next_mb->hash.rss | 1);
> > > 
> > > Why the logical OR is needed?
> > 
> > That's needed to ensure that we never track a tag with an actual value of zero.
> > We instead always force the low bit to be 1, so that we can use zero as an
> > "empty" value.
> 
> Bruce, could you check how this code may be better commented please?
> This discussion shows that the distributor library probably needs more
> explanations in the code or doxygen.
>

I've sent a patch adding in a couple of comments where I thought some additional
clarification might been needed. Any other places where more info is needed, just
let me know, and I'll be happy to patch that extra info in too.

/Bruce