From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?ISO-8859-1?Q?Michael_J=E4ntsch?= Subject: Re: [Socketcan-users] Message stalls in SocketCan Layer? Date: Fri, 03 Feb 2012 17:08:21 +0100 Message-ID: <4F2C0675.1050808@in.tum.de> References: <4F29091F.4010908@in.tum.de> <4F2AA5DF.9080304@grandegger.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mail-out1.informatik.tu-muenchen.de ([131.159.0.8]:40540 "EHLO mail-out1.informatik.tu-muenchen.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753719Ab2BCQPu (ORCPT ); Fri, 3 Feb 2012 11:15:50 -0500 Received: from [131.159.61.41] (atknoll184.informatik.tu-muenchen.de [131.159.61.41]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.in.tum.de (Postfix) with ESMTP id 59AF06559 for ; Fri, 3 Feb 2012 17:08:22 +0100 (CET) In-Reply-To: <4F2AA5DF.9080304@grandegger.com> Sender: linux-can-owner@vger.kernel.org List-ID: Cc: linux-can@vger.kernel.org Hi, thanks Wolfgang, I didn't know the socket-can mailinglist is deprecated= =2E On 02.02.2012 16:03, Wolfgang Grandegger wrote: > On 02/01/2012 10:42 AM, Michael J=E4ntsch wrote: >> Hi everyone, >> >> for about a month now, I have a problem with messages that get stall= ed, >> causing the select system call on several CAN sockets to time out. W= e're >> using the PEAK PCAN-USB interface on a Ubuntu 11.10 (kernel: >> 3.0.0-15-generic). I've been using the system for about 2 years now = and >> there were no revelant changes to the protocol or software lately. T= his >> problem occurs quite frequently now. > When did the reported problems start to show up? After switching to a > new kernel? yes, it all started when I switched to kernel 3.0.0-15-generic. However= , weirdly enough there is one computer with this kernel where the problem doesn't appear and two where it does. I think I will confirm this by going back to an older kernel and seeing if the problem disappears. >> What happens is, that our master sends out a message and receives 13 >> reply messages from 13 different nodes on the bus, at a frequency of >> 50Hz. This works for some time (minutes) and then a timeout on the >> select system call occurs that reads from the 13 sockets. Wireshark >> shows that there is an unusual time delay between the messages. They= get >> sent at the same time and are normally received within the time of >> 2-4ms. When the timeout occurs, this time is 30ms. When I turn on th= e >> debug information in the peak driver I see debug output with time >> stamps. On this layer the times are still ok when the timeout occurs= =2E >> Talking to the peak support, I got pointed at the socket can layer w= hich >> in this case might be causing the problem. However, I have no idea h= ow >> to debug this and find out more about the problem. > Hm, is there some other activity blocking the kernel? You could use > ftrace to find out what's going on. I don't know, it does look like something is blocking my kernel. However, I didn't really want to go into kernel debugging/tracing. If you can give me some hints, as to where I should start I could give it a shot... thanks a lot Michael --=20 Technische Universit=E4t M=FCnchen Michael J=E4ntsch =46akult=E4t f=FCr Informatik Robotics and Embedded Systems Parkring 13 85748 Garching bei M=FCnchen Tel: + 49.89.289.17626 =46ax: + 49.89.289.17637 michael.jaentsch@in.tum.de www6.in.tum.de