From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH net-next 0/2] sfc: enable 4-tuple UDP RSS hashing Date: Wed, 09 Nov 2016 13:59:36 -0500 (EST) Message-ID: <20161109.135936.1665492542584983522.davem@davemloft.net> References: <2c97d90b-bbb3-2cdc-7a72-597fd3f5231a@solarflare.com> <20161109.130918.1657511488354824947.davem@davemloft.net> <2932a4dc-cee0-47d1-d4a9-2b293e6155ad@solarflare.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, linux-net-drivers@solarflare.com To: ecree@solarflare.com Return-path: Received: from shards.monkeyblade.net ([184.105.139.130]:39322 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754077AbcKIS7h (ORCPT ); Wed, 9 Nov 2016 13:59:37 -0500 In-Reply-To: <2932a4dc-cee0-47d1-d4a9-2b293e6155ad@solarflare.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Edward Cree Date: Wed, 9 Nov 2016 18:51:15 +0000 > On 09/11/16 18:09, David Miller wrote: >> From: Edward Cree >> Date: Tue, 8 Nov 2016 13:02:05 +0000 >> >>> On 07/11/16 18:20, David Miller wrote: >>>> From: Edward Cree >>>> Date: Thu, 3 Nov 2016 22:10:31 +0000 >>>> >>>>> EF10 based NICs have configurable RSS hash fields, and can be made to take the >>>>> ports into the hash on UDP (they already do so for TCP). This patch series >>>>> enables this, in order to improve spreading of UDP traffic. >>>> What does the chip do with fragmented traffic? >>> Only the first fragment will be considered UDP, it will treat the rest as "other >>> IP" and 2-tuple hash them, probably hitting a different queue. >>> >>> My understanding is that while that will reduce performance, that shouldn't be a >>> problem as performance-sensitive users will avoid fragmentation anyway. >>> It could also lead to out-of-order packet delivery, but it's UDP so that's >>> supposed to be OK. >> Our software hashing never tries to inspect the ports for fragmented >> frames. And I'm pretty sure this is intentional. >> >> We should minimize the difference between what we do in software, which >> we fully control, and what we ask the hardware to offload for us. >> >> If you can't configure the chip to skip the ports for fragmented frames >> than I'm going to ask you to drop this. > I just checked and it turns out I was mistaken, we don't treat the first fragment > differently after all, we skip the ports for all fragments including the first. > Sorry for the misinformation. That's more in line with what is expected, series applied, thanks.