From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH net-next] flow_dissector: remove __flow_hash_consistentify Date: Wed, 29 Jul 2015 23:19:34 +0200 Message-ID: <1438204774.20182.109.camel@edumazet-glaptop2.roam.corp.google.com> References: <1438202943-937619-1-git-send-email-tom@herbertland.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: davem@davemloft.net, netdev@vger.kernel.org, kernel-team@fb.com To: Tom Herbert Return-path: Received: from mail-wi0-f181.google.com ([209.85.212.181]:36352 "EHLO mail-wi0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754067AbbG2VTh (ORCPT ); Wed, 29 Jul 2015 17:19:37 -0400 Received: by wicgb10 with SMTP id gb10so217917338wic.1 for ; Wed, 29 Jul 2015 14:19:36 -0700 (PDT) In-Reply-To: <1438202943-937619-1-git-send-email-tom@herbertland.com> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 2015-07-29 at 13:49 -0700, Tom Herbert wrote: > The intent of this function was to produce a consistent hash for both > directions of a flow. However, since we added more inputs to the flow > hashing (IPv6 flow labels for instance) in a lot of cases we won't get > the same hash computed for each direction anyway. Also, there is no > defined correlation between the hashes computed in each direction of a > flow. > > This patch removes the function since it is not providing significant > value and is expensive to be called for every packet. If there are > ever users of the flow_hash_from_keys that did require consistency > they can swap addresses and ports as needed in the flow_keys before > calling flow_hash_from_keys. Have you tested this change with conntracking and RPS enabled ? This was whole point from commit b249dcb82d327e41 I guess difference is even bigger today after removal of central conntracking lock.