From mboxrd@z Thu Jan 1 00:00:00 1970 From: Srinivas Pandruvada Subject: Re: [intel-pstate driver regression] processor frequency very high even if in idle Date: Fri, 01 Apr 2016 11:41:44 -0700 Message-ID: <1459536104.13525.148.camel@linux.intel.com> References: <2727017.UmaUvtBLeX@vostro.rjw.lan> <3623107.tlAuqH4F7s@vostro.rjw.lan> <1459532674.13525.136.camel@linux.intel.com> <003801d18c44$ab9134e0$02b39ea0$@net> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mga03.intel.com ([134.134.136.65]:58617 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751006AbcDASld (ORCPT ); Fri, 1 Apr 2016 14:41:33 -0400 In-Reply-To: <003801d18c44$ab9134e0$02b39ea0$@net> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Doug Smythies , =?ISO-8859-1?Q?=27J=F6rg?= Otte' , "'Rafael J. Wysocki'" Cc: "'Rafael J. Wysocki'" , 'Linux Kernel Mailing List' , 'Linux PM list' On Fri, 2016-04-01 at 11:31 -0700, Doug Smythies wrote: > On 2106.034.01 10:45 Srinivas Pandruvada wrote: > >=20 > > On Fri, 2016-04-01 at 16:06 +0200, J=C3=B6rg Otte wrote: > > >=20 > > > >=20 > > > > >=20 > > > > > >=20 > > > > > > >=20 > > > > > > >=20 > > > Done. Attached the tracer. > > > For me it looks like the previous one of the failing case. > > The traces show that idle task is constantly running without sleep. > No, I mean atleast on once CPU. I am not saying they are looping, but the wakeup time is less than 10ms, so the driver will not scale the load for idle time. > 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 > state > C0. That the sample rate is ending up at ~10 Milliseconds, indicates > some > high frequency (>=3D 100Hz) events on those CPUs. Those events, > apparently, > take very little CPU time to complete, hence a load of about 1% on > average. >=20 > 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 tar= get > pstate of > 20 where it should have remained at 16, but that is about it. >=20 > >=20 > > 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 > > task. > That column pretty much always says "idle" (or swapper for my way of > doing > things). I have not found it to very useful as an indicator, and > considerably > more so since the utilization changes. >=20 > >=20 > >=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. >=20 > ... Doug >=20 >=20 > -- > To unsubscribe from this list: send the line "unsubscribe linux-pm" > in > the body of a message to majordomo@vger.kernel.org > More majordomo info at=C2=A0=C2=A0http://vger.kernel.org/majordomo-in= fo.html