From mboxrd@z Thu Jan 1 00:00:00 1970 From: Carsten Emde Subject: Re: Variscite VAR-SOM-AM33 with patch-3.12.10-rt15 Date: Thu, 29 Oct 2015 19:45:06 +0100 Message-ID: <56326932.3090206@osadl.org> References: <5631DAE8.3000200@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit To: "mr. sindar" , linux-rt-users@vger.kernel.org Return-path: Received: from toro.web-alm.net ([62.245.132.31]:45899 "EHLO toro.web-alm.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751055AbbJ2Szr (ORCPT ); Thu, 29 Oct 2015 14:55:47 -0400 In-Reply-To: <5631DAE8.3000200@gmail.com> Sender: linux-rt-users-owner@vger.kernel.org List-ID: Sergey, > [..] > But when i enable load with codesyscontrol-system(about 80% CPU load), i > have following results: > System without RT-patch: > T: 0 ( 1412) P:80 I:10000 C: 10000 Min: 8 Act: 16 Avg: 13 Max: > 572 > System with RT-patch: > T: 0 ( 1549) P:80 I:10000 C: 10000 Min: 11 Act: 14 Avg: 17 Max: > 2492 > Is it normal that max jitter in system with RT-patch more(almost 5x > time) than in system without RT-patch, in this case? [..] 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. 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.