From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Doug Smythies" Subject: RE: [intel-pstate driver regression] processor frequency very high even if in idle Date: Fri, 1 Apr 2016 11:31:12 -0700 Message-ID: <003801d18c44$ab9134e0$02b39ea0$@net> References: <2727017.UmaUvtBLeX@vostro.rjw.lan> <3623107.tlAuqH4F7s@vostro.rjw.lan> <1459532674.13525.136.camel@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from cmta7.telus.net ([209.171.16.80]:60662 "EHLO cmta7.telus.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751124AbcDASbO convert rfc822-to-8bit (ORCPT ); Fri, 1 Apr 2016 14:31:14 -0400 In-Reply-To: <1459532674.13525.136.camel@linux.intel.com> Content-Language: en-ca Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: 'Srinivas Pandruvada' , =?UTF-8?Q?'J=C3=B6rg_Otte'?= , "'Rafael J. Wysocki'" Cc: "'Rafael J. Wysocki'" , 'Linux Kernel Mailing List' , 'Linux PM list' On 2106.034.01 10:45 Srinivas Pandruvada wrote: > On Fri, 2016-04-01 at 16:06 +0200, J=C3=B6rg Otte wrote: > > > > > >=20 >> Done. Attached the tracer. >> For me it looks like the previous one of the failing case. >=20 > The traces show that idle task is constantly running without sleep. No, they (at least the first one, I didn't look at the next one yet) show that CPUs 2 and 3 are spending around 99% of their time not in sta= te C0. That the sample rate is ending up at ~10 Milliseconds, indicates so= me high frequency (>=3D 100Hz) events on those CPUs. Those events, apparen= tly, take very little CPU time to complete, hence a load of about 1% on aver= age. By the way, I can recreate the high sample rate with virtually no load on my system easy, but so far have been unable to get the high CPU frequencies observed by J=C3=B6rg. I can get my system to about a targe= t pstate of 20 where it should have remained at 16, but that is about it. > The driver is processing samples for idle task for every 10ms and > aperf/mperf are showing that we are always in turbo mode for idle tas= k. That column pretty much always says "idle" (or swapper for my way of do= ing things). I have not found it to very useful as an indicator, and consid= erably more so since the utilization changes. >=20 > Need to find out why idle task is not sleeping. I contend that is it. I don't have enough reverted data, but so far this seems very much like that bug report I referenced earlier. =2E.. Doug