From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH 1/4]: net: Allow RX queue selection to seed TX queue hashing. Date: Wed, 28 Jan 2009 12:22:31 -0800 (PST) Message-ID: <20090128.122231.208600152.davem@davemloft.net> References: <20090127.164027.245779962.davem@davemloft.net> <20090128085358.GA15593@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: herbert@gondor.apana.org.au Return-path: Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:58525 "EHLO sunset.davemloft.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751565AbZA1UWe (ORCPT ); Wed, 28 Jan 2009 15:22:34 -0500 In-Reply-To: <20090128085358.GA15593@gondor.apana.org.au> Sender: netdev-owner@vger.kernel.org List-ID: From: Herbert Xu Date: Wed, 28 Jan 2009 19:53:58 +1100 > So can you think of a scenario where we really need this added > protection? No matter what you think about the randomness aspect, our divide avoidance technique being used here will still get in the way of the situations you seem to be concerned about. We do the jhash et al. magic in order to be able to use a multiply to get the modulus. So the function computing from RX to TX queue numbers will never be straightforward. And since we do need to do the jhash to make that multiply trick work, the randomness comes essentially for free and does not make the RX to TX queue relationship any more or less straightforward.