From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stanislav Meduna Subject: Re: Measuring scheduling latency for RT threads Date: Wed, 19 Nov 2014 14:19:49 +0100 Message-ID: <546C98F5.1020103@meduna.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE To: =?UTF-8?B?SsO8cmdlbiBMYW5uZXI=?= , linux-rt-users@vger.kernel.org Return-path: Received: from www.meduna.org ([92.240.244.38]:60878 "EHLO meduna.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751747AbaKSNT6 (ORCPT ); Wed, 19 Nov 2014 08:19:58 -0500 In-Reply-To: Sender: linux-rt-users-owner@vger.kernel.org List-ID: On 19.11.2014 13:43, "J=C3=BCrgen Lanner" wrote: > My first goal is to find out about the worst case latency: > Is there a way I can find out how long (worst case) a RT thread > being ready to run is just waiting to be dispatched? =20 ftrace, trace-cmd, kernelshark The latency for the highest prio runnable task is available right away with the wakeup tracer. For other tasks you can trace the scheduling functions and interpret the results using a script (or look at them graphically using kernelshark). Note that the function tracing is not free and will skew the results a bit, but should be good enough to identify the offenders. --=20 Stano -- To unsubscribe from this list: send the line "unsubscribe linux-rt-user= s" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html