From mboxrd@z Thu Jan 1 00:00:00 1970 From: "mr. sindar" Subject: Re: Variscite VAR-SOM-AM33 with patch-3.12.10-rt15 Date: Fri, 30 Oct 2015 11:08:12 +0300 Message-ID: <5633256C.9090109@gmail.com> References: <5631DAE8.3000200@gmail.com> <56326932.3090206@osadl.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit To: Carsten Emde , linux-rt-users@vger.kernel.org Return-path: Received: from mail-lf0-f52.google.com ([209.85.215.52]:32976 "EHLO mail-lf0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758633AbbJ3IIU (ORCPT ); Fri, 30 Oct 2015 04:08:20 -0400 Received: by lfbf136 with SMTP id f136so15536567lfb.0 for ; Fri, 30 Oct 2015 01:08:18 -0700 (PDT) In-Reply-To: <56326932.3090206@osadl.org> Sender: linux-rt-users-owner@vger.kernel.org List-ID: 29/10/15 21:45, Carsten Emde: > Is the codesyscontrol system running at priority above 80 or below? If > above, then at least the second result makes sense, since on a > single-core system only the one task that runs at highest priority is > the real-time task that enjoys the worst-case latency of the system. All > other tasks do not. If, however, priority 80 of the cyclictest task is > the highest priority of all tasks, then you may have detected a problem > that needs to be fixed. > I executed codesyscontrol without setting any priority and scheduling policy. When i execute chrt -p , it shows: pid 1532's current scheduling policy: SCHED_OTHER pid 1532's current scheduling priority: 0 But now i think it wasn't true. After your advice i execute cyclitest with maximum priority(99), and results became deterministic. ./cyclictest -t1 -p 99 -n -i 10000 -l 10000 # /dev/cpu_dma_latency set to 0us policy: fifo: loadavg: 4.95 4.39 2.80 2/77 1533 T: 0 ( 1533) P:99 I:10000 C: 10000 Min: 13 Act: 20 Avg: 20 Max: 62 > Note that cyclictest is intended as a placeholder of a real-time task > for people who do not have their own user-space real-time project, for > example kernel developers and board manufacturers. Once you have your > own real-time application, you better equip it with internal real-time > checks in a similar way as cyclictest does it, but you should not run > cyclictest in parallel. > > Thanks, > -Carsten. The real goal for me, indeed, is running codesyscontrol, which is runs IEC 61131-3 industrial programs. First i tried codesyscontrol run on Linux without RT-patch. It was sporadic multiplying of cycle time of IEC 61131-3-program. And then i decide to try RT-patch. But multiplying of cycle time in CodeSys is still appears, even when it runs with 99 priority. So now i think it's a problem in CodeSys runtime system(as i convinced with your advice, that RT-patch works well), i wrote this issue to their support(because we are buying binary package of CodeSys, i can't do with this any programming hacks, but only administrative). Thank You very much for help! -- Best regards, Sergey.