From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Hutchings Subject: Re: ip_summed setting for TCP pure-ACK packets Date: Tue, 09 Nov 2010 16:24:48 +0000 Message-ID: <1289319889.2238.195.camel@achroite.uk.solarflarecom.com> References: <1289234113.2222.20.camel@achroite.uk.solarflarecom.com> <1289235366.15376.3.camel@edumazet-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: David Miller , sf-linux-drivers , netdev To: Eric Dumazet Return-path: Received: from exchange.solarflare.com ([216.237.3.220]:18361 "EHLO exchange.solarflare.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751223Ab0KIQYx convert rfc822-to-8bit (ORCPT ); Tue, 9 Nov 2010 11:24:53 -0500 In-Reply-To: <1289235366.15376.3.camel@edumazet-laptop> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, 2010-11-08 at 17:56 +0100, Eric Dumazet wrote:=20 > Le lundi 08 novembre 2010 =C3=A0 16:35 +0000, Ben Hutchings a =C3=A9c= rit : > > As we discussed at LPC: > >=20 > > Current controllers handled by the sfc driver have a per-queue (rat= her > > than per-packet) option for checksum generation. Currently pure-AC= K > > packets sent by TCP have ip_summed =3D=3D CHECKSUM_NONE and we must= send > > them on hardware queues with checksum generation disabled. To supp= ort > > this, we allocate 2 hardware queues per core TX queue. > >=20 > > To reduce the risk of reordering (and possibly the number of hardwa= re TX > > queues required), it would be helpful for TCP to set ip_summed =3D=3D > > CHECKSUM_PARTIAL on pure-ACK packets when the output device is know= n to > > support checksum generation. > >=20 > > Ben. > >=20 >=20 > Hmm >=20 > Do you mean commit 2e8e18ef52e7dd1af0a3bd1 is not enough ? It might well be... I must admit I hadn't thought to check whether this issue had gone away. Yes, that does the trick. Sorry for wasting people's time on this. Ben. --=20 Ben Hutchings, Senior Software Engineer, Solarflare Communications Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked.