From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751721AbeCUKBa (ORCPT ); Wed, 21 Mar 2018 06:01:30 -0400 Received: from vegas.theobroma-systems.com ([144.76.126.164]:45021 "EHLO mail.theobroma-systems.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751459AbeCUKB1 (ORCPT ); Wed, 21 Mar 2018 06:01:27 -0400 Subject: Re: [bug, bisected] pfifo_fast causes packet reordering From: Jakob Unterwurzacher To: John Fastabend , Dave Taht Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, "David S. Miller" , "linux-can@vger.kernel.org" , Martin Elshuber References: <946dbe16-a2eb-eca8-8069-468859ccc78d@theobroma-systems.com> <95844480-d020-9000-53ef-0da8b965ce6e@gmail.com> <3a959e50-8656-5d9c-97b9-227d733948f8@theobroma-systems.com> <5aeb54ba-2d96-4ab5-53c4-2d3691be7acc@gmail.com> <340a6c54-6031-5522-98f5-eafdd3a37a38@theobroma-systems.com> Message-ID: <00cc2d41-6861-9a9c-603f-ba8013b2e2ce@theobroma-systems.com> Date: Wed, 21 Mar 2018 11:01:17 +0100 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <340a6c54-6031-5522-98f5-eafdd3a37a38@theobroma-systems.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 16.03.18 11:26, Jakob Unterwurzacher wrote: > On 15.03.18 23:30, John Fastabend wrote: >>> I have reproduced it using two USB network cards connected to each >>> other. The test tool sends UDP packets containing a counter and >>> listens on the other interface, it is available at >>> https://github.com/jakob-tsd/pfifo_stress/blob/master/pfifo_stress.py >> >> Great thanks, can you also run this with taskset to bind to >> a single CPU, >> >>   # taskset 0x1 ./pifof_stress.py >> >> And let me know if you still see the OOO. > > Interesting. Looks like it depends on which core it runs on. CPU0 is > clean, CPU1 is not. So we are at v4.16-rc6 now - have you managed to reproduce this is or should I try to get the revert correct? Best regards, Jakob