From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Hutchings Subject: Re: [PATCH 0/2] Disable forwarding of LRO skbs Date: Thu, 1 May 2008 13:08:51 +0100 Message-ID: <20080501120850.GH14219@solarflare.com> References: <20080430214845.GC14219@solarflare.com> <20080501110225.GG14219@solarflare.com> <1209640128.4191.30.camel@moonstone.uk.level5networks.com> <20080501111247.GA7756@gondor.apana.org.au> <1209640688.4191.35.camel@moonstone.uk.level5networks.com> <20080501113716.GA7955@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Kieran Mansley , davem@davemloft.net, shemminger@vyatta.com, netdev@vger.kernel.org To: Herbert Xu Return-path: Received: from 82-69-137-158.dsl.in-addr.zen.co.uk ([82.69.137.158]:37883 "EHLO uklogin.uk.level5networks.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1756733AbYEAMJe (ORCPT ); Thu, 1 May 2008 08:09:34 -0400 Content-Disposition: inline In-Reply-To: <20080501113716.GA7955@gondor.apana.org.au> Sender: netdev-owner@vger.kernel.org List-ID: Herbert Xu wrote: > On Thu, May 01, 2008 at 12:18:08PM +0100, Kieran Mansley wrote: > > > > If I remember rightly it also gets upset when it comes to split the > > packet because the frag_list is already in use; it expects this not to > > be the case for GSO but it's valid for an LRO packet to do this I think. > > I don't think there's anything fundamentally difficult here, it's just > > that the code has never been written to cope. > > Oh so LRO packets still preserve the original packet boundaries? > That's even easier. We could just make the GSO output code detect > the presence of frag_list and fragment based on that. Depending on the driver, the packets may be received into skbs which are then attached to frag_list, or into page buffers which go in the frags array. If most packets can be merged by LRO, deferring skb allocation and using the frags array is a performance win. Ben. -- Ben Hutchings, Senior Software Engineer, Solarflare Communications Not speaking for my employer; that's the marketing department's job.