netdev - Re: [PATCH 10/13]: net: Implement simple sw TX hashing.

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Message-Id: <20080714.045806.213105998.davem@davemloft.net>
Date:	Mon, 14 Jul 2008 04:58:06 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	herbert@...dor.apana.org.au
Cc:	dada1@...mosbay.com, netdev@...r.kernel.org
Subject: Re: [PATCH 10/13]: net: Implement simple sw TX hashing.

From: Herbert Xu <herbert@...dor.apana.org.au>
Date: Mon, 14 Jul 2008 19:33:02 +0800

> Eric Dumazet <dada1@...mosbay.com> wrote:
> >
> >> +     return hash % dev->real_num_tx_queues;
> > 
> > simple but expensive... but could be changed to use reciprocal_divide() if necessary...
> 
> For the common cases it should be a power of 2 too.

Unfortunately it is not enforcable for it to be a power of 2
and I fear it will in fact not be very often for several
chips that will use this stuff.

BTW, how can reciprocal_divide() be used to compute a modulus?  Are
you going to do the reciprocal divide, re-multiply, then subtract?
:-)

Sorry I haven't replied yet to all of this useful feedback, I'm still
killing myself to finish making the entire generic networking
multiqueue aware :(
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