From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthias Fuchs Subject: Re: 3.12.6-rt9 on AM335x (armv7) Date: Tue, 07 Jan 2014 22:20:20 +0100 Message-ID: <52CC6F94.6070906@ma-fu.de> References: <52C44448.3030405@ma-fu.de> <52CB0881.9000502@ma-fu.de> <15611103.51LOkxSQt9@dabox> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: linux-rt-users To: Tim Sander Return-path: Received: from mo4-p00-ob.smtp.rzone.de ([81.169.146.217]:35722 "EHLO mo4-p00-ob.smtp.rzone.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751350AbaAGVU1 (ORCPT ); Tue, 7 Jan 2014 16:20:27 -0500 In-Reply-To: <15611103.51LOkxSQt9@dabox> Sender: linux-rt-users-owner@vger.kernel.org List-ID: Hi Tim, without hackbench and frieds (idle system) I get a max. latency of abou= t 4ms. Running hackbench (default arguments, -l 1000), it still increases up = to 5ms: =2E.. # Total: 000000193 # Min Latencies: 00024 # Avg Latencies: 00205 # Max Latencies: 05058 =2E.. The obvious PM stuff is disabled. No dynamic frequency scaling, etc. Really weired stuff. I already mentioned the 3.2 system with the same C= PU in the OSADL lab. It comes with max. latency of 118us. So I really expect something = similiar. Matthias On 01/07/2014 09:38 AM, Tim Sander wrote: > Hi >> after some chatting with Nicholas and being sure that I didn't do an= ything >> totally stupid I would like to provide my current kernel config and = a trace >> generated by "cyclictest ... -b500". >> >> kernel config -> https://www.dropbox.com/s/zsud0b77xoosjm1/config >> trace -> >> https://www.dropbox.com/s/5uf58oqo0qwcn4x/trace-cyclictest-2508us.tx= t >> >> I still get max latencies of about 4000us on this TI AM335x system r= unning >> 3.12.6-rt9 with timers-do-not-raise-softirq-unconditionally.patch re= verse >> applied. >> >> sched_rt_runtime_us and sched_rt_period_us are identical. The system= is idle >> during the test. Rootfilesystem comes via NFS. >> >> root@generic-armv7a:~# cat /proc/sys/kernel/sched_rt_runtime_us >> 1000000 >> root@generic-armv7a:~# cat /proc/sys/kernel/sched_rt_period_us >> 1000000 >> >> root@generic-armv7a:~# uname -a >> Linux generic-armv7a 3.12.6-rt9-dirty #3 SMP PREEMPT RT Sat Jan 4 23= :01:19 >> CET 2014 armv7l GNU/Linux >> >> root@generic-armv7a:~# ~/cyclictest -p99 -m -n -i200 -h400 -q -l1000= 00 -b >> 500 # /dev/cpu_dma_latency set to 0us >> INFO: debugfs mountpoint: /sys/kernel/debug/tracing/ >> could not set ftrace_enabled to 0 >> could not set tracing_max_latency to 0 >> # Histogram >> ... >> # Total: 000018604 >> # Min Latencies: 00024 >> # Avg Latencies: 00158 >> # Max Latencies: 02508 > Wohaa, thats bad for a latency patched kernel. Have you disabled=20 > powermanagement? I have an older rt patched kernel and it was not too= good. > If i remember correctly it was between 100-200=B5s latency. But thats > far better than this. You could also load the system with hackbench, = if its=20 > the idle pm than latency would get better. >=20 > Best regards > Tim >=20 > -- > To unsubscribe from this list: send the line "unsubscribe linux-rt-us= ers" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >=20 -- 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