From mboxrd@z Thu Jan 1 00:00:00 1970 From: Edward Cree Subject: Re: [PATCH net-next 0/2] sfc: enable 4-tuple UDP RSS hashing Date: Tue, 8 Nov 2016 13:02:05 +0000 Message-ID: <2c97d90b-bbb3-2cdc-7a72-597fd3f5231a@solarflare.com> References: <20161107.132003.727799156798583121.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: , To: David Miller Return-path: Received: from nbfkord-smmo04.seg.att.com ([209.65.160.86]:28751 "EHLO nbfkord-smmo04.seg.att.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932675AbcKHNCR (ORCPT ); Tue, 8 Nov 2016 08:02:17 -0500 In-Reply-To: <20161107.132003.727799156798583121.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: 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.