From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Fastabend Subject: Re: [bug, bisected] pfifo_fast causes packet reordering Date: Thu, 15 Mar 2018 15:30:55 -0700 Message-ID: <5aeb54ba-2d96-4ab5-53c4-2d3691be7acc@gmail.com> References: <946dbe16-a2eb-eca8-8069-468859ccc78d@theobroma-systems.com> <95844480-d020-9000-53ef-0da8b965ce6e@gmail.com> <3a959e50-8656-5d9c-97b9-227d733948f8@theobroma-systems.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, "David S. Miller" , "linux-can@vger.kernel.org" , Martin Elshuber To: Jakob Unterwurzacher , Dave Taht Return-path: In-Reply-To: <3a959e50-8656-5d9c-97b9-227d733948f8@theobroma-systems.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 03/15/2018 11:08 AM, Jakob Unterwurzacher wrote: > On 14.03.18 05:03, John Fastabend wrote: >> On 03/13/2018 11:35 AM, Dave Taht wrote: >>> On Tue, Mar 13, 2018 at 11:24 AM, Jakob Unterwurzacher >>> wrote: >>>> During stress-testing our "ucan" USB/CAN adapter SocketCAN driver on Linux >>>> v4.16-rc4-383-ged58d66f60b3 we observed that a small fraction of packets are >>>> delivered out-of-order. >>>> >> >> Is the stress-testing tool available somewhere? What type of packets >> are being sent? > > > 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. > Here is what I get: > > root@rk3399-q7:~# ./pfifo_stress.py > [...] > expected ctr 0xcdc, received 0xcdd > expected ctr 0xcde, received 0xcdc > expected ctr 0xcdd, received 0xcde > expected ctr 0xe3c, received 0xe3d > expected ctr 0xe3e, received 0xe3c > expected ctr 0xe3d, received 0xe3e > expected ctr 0x1097, received 0x1098 > expected ctr 0x1099, received 0x1097 > expected ctr 0x1098, received 0x1099 > expected ctr 0x17c0, received 0x17c1 > expected ctr 0x17c2, received 0x17c0 > [...] > > Best regards, > Jakob