From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Greear Subject: Re: How to do TCP tx checksums Date: Tue, 17 Nov 2015 10:32:28 -0800 Message-ID: <564B72BC.6060702@candelatech.com> References: <564A72D3.1050407@candelatech.com> <564B677C.8000603@candelatech.com> <1447784807.22599.125.camel@edumazet-glaptop2.roam.corp.google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Tom Herbert , netdev To: Eric Dumazet Return-path: Received: from mail2.candelatech.com ([208.74.158.173]:37649 "EHLO mail2.candelatech.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753645AbbKQSc3 (ORCPT ); Tue, 17 Nov 2015 13:32:29 -0500 In-Reply-To: <1447784807.22599.125.camel@edumazet-glaptop2.roam.corp.google.com> Sender: netdev-owner@vger.kernel.org List-ID: On 11/17/2015 10:26 AM, Eric Dumazet wrote: > On Tue, 2015-11-17 at 09:44 -0800, Ben Greear wrote: > >> And in case it helps, here is the output from dmesg. >> >> This is an Ethernet frame, and in this case csum-start is the >> index of the first byte of the TCP header as far as I can tell. >> >> [64967.194251] check: 0xf51b csum-start: 34 offset: 16 summed: 0x3 saddr: 0x201010a daddr: 0x101010a len: 1514 >> > > You forgot to clear tcp header @check before calling > __tcp_v4_send_check(), I think. > > ( th->check = 0; ) From printk I added to e1000e, it looks like I have bad offsets somehow. I'll try clearing check as well, however. > Anyway, just use trafgen and get ~6 Mpps, more easily than with pktgen. I do plan to look at this...but need to make sure I can get similar features before I ditch pktgen. It's not just raw throughput that is of interest to me, but also randomizing, sequential, etc header fields to test various network equipment (routers, MAC tables in switches, etc). Thanks, Ben -- Ben Greear Candela Technologies Inc http://www.candelatech.com