From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 1314 invoked by alias); 7 Jun 2011 02:18:54 -0000 Received: (qmail 1304 invoked by uid 22791); 7 Jun 2011 02:18:53 -0000 X-SWARE-Spam-Status: No, hits=-1.1 required=5.0 tests=AWL,BAYES_00,RCVD_IN_SORBS_WEB,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from netic.com (HELO netic.com) (208.131.130.247) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Tue, 07 Jun 2011 02:18:39 +0000 Received: from [10.128.176.189] ([202.81.69.153]) by netic.com (8.13.1/8.13.1) with ESMTP id p572IV32008117; Mon, 6 Jun 2011 20:18:34 -0600 References: <1478E21E-D36A-4451-9F69-0042CBF57E91@netic.com> In-Reply-To: Mime-Version: 1.0 (iPhone Mail 8J2) Content-Type: text/plain; charset=us-ascii Message-Id: Content-Transfer-Encoding: 7bit Cc: "ecos-discuss@sources.redhat.com" From: Laurie Gellatly Date: Tue, 07 Jun 2011 02:18:00 -0000 To: Grant Edwards X-IsSubscribed: yes Mailing-List: contact ecos-discuss-help@ecos.sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: ecos-discuss-owner@ecos.sourceware.org Subject: Re: [ECOS] Re: How to use IP/UDP/TCP checksum offload HW? X-SW-Source: 2011-06/txt/msg00030.txt.bz2 On 07/06/2011, at 10:57 AM, Grant Edwards wrote: > On 2011-06-07, Laurie Gellatly wrote: > >> I tried to enable this before without success. > > Ah yes, I saw your (unanswered) post from a few years back asking > about this. I was hoping there had been some progress since then. > >> I agree that its a waste of processor time when it can be performed >> in hardware. > > The last time I did some profiling, IP checksum calculation was a > pretty significant bottleneck for TCP throughput. Back in the NetBSD > stack days, I got about a 20% improvement in throughput by writing my > own assembly-language IP checksum routine for ARM7. The FreeBSD C > implementation and more recent versions of gcc do almost as well as > hand-tuned assembly, but it's still a big percentage of CPU usage in > TCP communications -- and it will be even worse now that I have a chip > that does scatter-gather DMA. A part for US $4 that has IP checksum > offloading and scatter-gather DMA. Back when I was a new grad... > >> Must we look at the latest BSD code to see how to implement this? > > Maybe. Or there might be a simpler way to do it. I would guess that > the current FreeBSD has an API to configure this on a per-interface > basis at run-time. > > If we can assume that there is only one external interface, then we > don't need any API or runtime checks, just a few strategic #if/#endif > pairs and some CDL to control them. > > -- > Grant > > > -- > Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos > and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss > So how do we progress this? Should we offline exchange the mods we've each tried (code and CDL)? ...Laurie:{) -- Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss