From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bernhard Schiffner Subject: Re: Measuring scheduling latency for RT threads Date: Wed, 19 Nov 2014 14:11:37 +0100 Message-ID: <9785835.e6QRrDJeRk@bs8> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit To: linux-rt-users@vger.kernel.org Return-path: Received: from mout.kundenserver.de ([212.227.126.130]:57507 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752736AbaKSNLq (ORCPT ); Wed, 19 Nov 2014 08:11:46 -0500 In-Reply-To: Sender: linux-rt-users-owner@vger.kernel.org List-ID: Am Mittwoch, 19. November 2014, 13:43:36 schrieben Sie: > I have a complex automation project with makes heavy use of real time prio > threads working with external hardware connected by e.g. TCP/IP. IMHO most > of my latencies simply come from the fact that there are multiple threads > running on the same RT prio being scheduled FIFO. (poor design, yes, but > that's what I want to fix) Expected response time is in low millsecond > area, so no miroseconds juggling here. The process is running (alone, no > other processes there) on one CPU of an i5 quad core (using 3.13.0-35 > ubuntu 14.04) The expected behavior is "in general" only achiveable with patched kernels. The RT-patches are available here: https://www.kernel.org/pub/linux/kernel/projects/rt/ (Notice availability only for even kernel numbers.) So please get first of all a kernel working suited for "real realtime". This step should be quite simple :-) Good luck! Bernhard