From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefan Jenisch Subject: Difficulties with cyclictest on AMD CPU Date: Sun, 27 Apr 2014 13:01:08 +0200 Message-ID: <535CE374.7050907@gmail.com> 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 mail-ee0-f53.google.com ([74.125.83.53]:45592 "EHLO mail-ee0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752514AbaD0LBN (ORCPT ); Sun, 27 Apr 2014 07:01:13 -0400 Received: by mail-ee0-f53.google.com with SMTP id b57so3957899eek.40 for ; Sun, 27 Apr 2014 04:01:11 -0700 (PDT) Received: from [192.168.0.10] (82-194-155-17.dyn.salzburg-online.at. [82.194.155.17]) by mx.google.com with ESMTPSA id o5sm40818968eeg.8.2014.04.27.04.01.09 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sun, 27 Apr 2014 04:01:09 -0700 (PDT) Sender: linux-rt-users-owner@vger.kernel.org List-ID: Hello folks! I am having some difficulties with cyclictest on an =93AMD GX-210HA SOC= =20 with Radeon(tm) HD Graphics=94 CPU. Latency values are better with some= =20 CPU load (execution of an endless loop) than without. When running the command =93cyclictest -c 0 -t15 -p 95 -i 500 -n -l=20 100000=94 I get the output: policy: fifo: loadavg: 0.25 0.09 0.06 1/201 2349 T: 0 ( 2335) P:95 I:500 C: 100000 Min: 11 Act: 19 Avg: 21 Max: 231 T: 1 ( 2336) P:95 I:1000 C: 50000 Min: 10 Act: 13 Avg: 23 Max: 222 T: 2 ( 2337) P:95 I:1500 C: 33333 Min: 11 Act: 19 Avg: 24 Max: 198 T: 3 ( 2338) P:95 I:2000 C: 25000 Min: 10 Act: 16 Avg: 25 Max: 185 T: 4 ( 2339) P:95 I:2500 C: 20000 Min: 12 Act: 22 Avg: 25 Max: 196 T: 5 ( 2340) P:95 I:3000 C: 16666 Min: 11 Act: 20 Avg: 23 Max: 233 T: 6 ( 2341) P:95 I:3500 C: 14285 Min: 12 Act: 19 Avg: 25 Max: 209 T: 7 ( 2342) P:95 I:4000 C: 12500 Min: 10 Act: 13 Avg: 25 Max: 123 T: 8 ( 2343) P:95 I:4500 C: 11111 Min: 11 Act: 65 Avg: 29 Max: 203 T: 9 ( 2344) P:95 I:5000 C: 10000 Min: 11 Act: 26 Avg: 22 Max: 175 T:10 ( 2345) P:95 I:5500 C: 9091 Min: 13 Act: 30 Avg: 31 Max: 165 T:11 ( 2346) P:95 I:6000 C: 8333 Min: 12 Act: 19 Avg: 23 Max: 161 T:12 ( 2347) P:95 I:6500 C: 7692 Min: 12 Act: 19 Avg: 24 Max: 194 T:13 ( 2348) P:95 I:7000 C: 7142 Min: 12 Act: 64 Avg: 23 Max: 185 T:14 ( 2349) P:95 I:7500 C: 6666 Min: 12 Act: 20 Avg: 23 Max: 192 Now the thing is when getting the CPUs a little bit busy with something= =20 else(e.g. simultaneous running =93while true; do echo loop; done=94 on = in=20 another shell) the same cyclictest results in: root@host:[~]# cyclictest -c 0 -t15 -p 95 -i 500 -n -l 100000 policy: fifo: loadavg: 1.78 0.54 0.22 3/203 2431 T: 0 ( 2417) P:95 I:500 C: 100000 Min: 10 Act: 19 Avg: 16 Max: 44 T: 1 ( 2418) P:95 I:1000 C: 49998 Min: 10 Act: 16 Avg: 15 Max: 45 T: 2 ( 2419) P:95 I:1500 C: 33335 Min: 9 Act: 16 Avg: 15 Max: 33 T: 3 ( 2420) P:95 I:2000 C: 25000 Min: 10 Act: 14 Avg: 16 Max: 40 T: 4 ( 2421) P:95 I:2500 C: 20000 Min: 10 Act: 15 Avg: 16 Max: 33 T: 5 ( 2422) P:95 I:3000 C: 16667 Min: 10 Act: 15 Avg: 16 Max: 60 T: 6 ( 2423) P:95 I:3500 C: 14286 Min: 10 Act: 14 Avg: 16 Max: 35 T: 7 ( 2424) P:95 I:4000 C: 12500 Min: 12 Act: 24 Avg: 16 Max: 33 T: 8 ( 2425) P:95 I:4500 C: 11111 Min: 11 Act: 15 Avg: 16 Max: 34 T: 9 ( 2426) P:95 I:5000 C: 10000 Min: 10 Act: 15 Avg: 17 Max: 46 T:10 ( 2427) P:95 I:5500 C: 9091 Min: 10 Act: 15 Avg: 15 Max: 38 T:11 ( 2428) P:95 I:6000 C: 8333 Min: 10 Act: 13 Avg: 15 Max: 35 T:12 ( 2429) P:95 I:6500 C: 7692 Min: 11 Act: 13 Avg: 16 Max: 42 T:13 ( 2430) P:95 I:7000 C: 7143 Min: 11 Act: 12 Avg: 16 Max: 32 T:14 ( 2431) P:95 I:7500 C: 6666 Min: 11 Act: 15 Avg: 17 Max: 37 As can be seen the max-latency improved! It=92s like ordering in an empty restaurant. Takes hours to get the din= ner=20 if you are the only customer. As soon as some more people are around=20 everything is getting faster... So my guess is that the cpu goes into some sort of powersave mode from=20 time to time. The wakeup from these powersave state results in=20 latencies. Currently I am looking for a proper solution to this problem= =20 and what I have tried so far: - BIOS upgrade - Upgraded to linux-3.10.12-rt25 - Disabling all sort of powersave modes in the kernel config - Activated cpufreq-performance (which seems to be ignored anyway) - Searched the BIOS for any powersave modes to deactivate (none found) I got rather clueless on what else to try! Does anyone has a helping=20 hint on how to solve this one??? With many thanks in advance, Stefan J. -- 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