From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Paul-Ehrlich@gmx.de" Subject: Realtime System only works after running cyclictest with -b option Date: Thu, 01 Aug 2013 19:34:31 +0200 Message-ID: <51FA9C27.7050409@gmx.de> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE To: linux-rt-users@vger.kernel.org Return-path: Received: from mout.gmx.net ([212.227.17.20]:55398 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751194Ab3HARee (ORCPT ); Thu, 1 Aug 2013 13:34:34 -0400 Received: from [192.168.0.100] ([146.52.2.203]) by mail.gmx.com (mrgmx102) with ESMTPSA (Nemesis) id 0MB1C4-1UxHG02ykW-00A27q for ; Thu, 01 Aug 2013 19:34:32 +0200 Sender: linux-rt-users-owner@vger.kernel.org List-ID: Hello linux-rt-users, I have a question concerning RT-Patch, which shows strange behavior=20 discoverd using cyclictest. I have an embedded system with patched RT.=20 The max latency of the cyclictest isn=92t as low as expected and my onl= y=20 application hangs to, so I included tracing abilities to the kernel to=20 use the =93-b=94 switch of cyclictest. But the kernel behaves different= if=20 switched on (detailed below)? Maybe you can give me a hint what the=20 cyclictest does when using the =96b switch. It somehow persists after t= he=20 option is used once and my own application runs fine afterwards too. So= =20 in order to run my application right now I have to run cyclictest with=20 the -b option after each reboot. Many Thanks in Advance Paul Ehrlich =46irst test run after boot - showing huge latencies: linaro@linaro-ubuntu-desktop:~$ sudo cyclictest -t1 -p 80 -n -i 250 -l=20 10000 -a 1 # /dev/cpu_dma_latency set to 0us policy: fifo: loadavg: 0.74 0.34 0.13 1/144 1966 T: 0 ( 1966) P:80 I:250 C: 10000 Min: 18 Act: 27 Avg: 36 Max: 1590 Secound test run after boot - just to make sure: linaro@linaro-ubuntu-desktop:~$ sudo cyclictest -t1 -p 80 -n -i 250 -l=20 10000 -a 1 # /dev/cpu_dma_latency set to 0us policy: fifo: loadavg: 0.93 0.30 0.10 1/142 1948 T: 0 ( 1948) P:80 I:250 C: 10000 Min: 18 Act: 46 Avg: 38 Max: 3639 Third test run after boot now using -b option - result looks ok for the= =20 system: linaro@linaro-ubuntu-desktop:~$ sudo cyclictest -t1 -p 80 -n -i 250 -l=20 10000 -a 1 -b 1000 # /dev/cpu_dma_latency set to 0us INFO: debugfs mountpoint: /sys/kernel/debug/tracing/ policy: fifo: loadavg: 0.51 0.32 0.13 1/144 1979 T: 0 ( 1979) P:80 I:250 C: 10000 Min: 85 Act: 101 Avg: 114 Max: 179 =46ourth run after boot - now without -b even faster?: # Thread Ids: 01979 linaro@linaro-ubuntu-desktop:~$ sudo cyclictest -t1 -p 80 -n -i 250 -l=20 10000 -a 1 # /dev/cpu_dma_latency set to 0us policy: fifo: loadavg: 0.66 0.38 0.16 1/157 2283 T: 0 ( 2279) P:80 I:250 C: 10000 Min: 6 Act: 27 Avg: 27 Max: 51 -- 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