From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755076AbcI2CXL (ORCPT ); Wed, 28 Sep 2016 22:23:11 -0400 Received: from mail-oi0-f42.google.com ([209.85.218.42]:33550 "EHLO mail-oi0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750700AbcI2CXB (ORCPT ); Wed, 28 Sep 2016 22:23:01 -0400 Subject: Re: Regression in 4.8 - CPU speed set very low To: "Rafael J. Wysocki" References: <3919370.SGLjGupePs@vostro.rjw.lan> <075788ab-34e0-803c-f2b4-3f370ecc6b14@lwfinger.net> <2477506.olat0BX4ex@vostro.rjw.lan> <1436996d-078b-aa51-4452-b6655d917135@lwfinger.net> <594f5012-5157-bfdd-f715-bea8caa824c3@lwfinger.net> <2326a7dd-675f-752b-f100-5dce6e4c93fd@lwfinger.net> <003001d2186d$02c34820$0849d860$@net> <785b1633-5f1d-7cfe-5a9f-cfbb82a4a754@lwfinger.net> Cc: Doug Smythies , Srinivas Pandruvada , "Rafael J. Wysocki" , LKML , Linux PM list From: Larry Finger Message-ID: <5271ed6f-5798-e930-d7fd-17fe6bb7ea96@lwfinger.net> Date: Wed, 28 Sep 2016 21:22:59 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.3.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/27/2016 06:46 AM, Rafael J. Wysocki wrote: > On Tue, Sep 27, 2016 at 10:48 AM, Larry Finger > wrote: >> On 09/26/2016 10:12 PM, Doug Smythies wrote: >>> >>> On 2016.09.26 18:31 Srinivas Pandruvada wrote: >>>> >>>> On Mon, 2016-09-26 at 19:48 -0500, Larry Finger wrote: >>>>> >>>>> On 09/26/2016 07:21 PM, Rafael J. Wysocki wrote: >>>>>> >>>>>> On Tue, Sep 27, 2016 at 1:53 AM, Larry Finger wrote: >>>>>> But for both we need a reproducer anyway. >>>>> >>>>> I do not have a reliable reproducer. The condition has always >>>>> happened when >>>>> running a high-compute job such as a 'make -j8' on the kernel, or >>>>> building the >>>>> RPM for openSUSE's implementation of VirtualBox. The latter is what >>>>> I'm using >>>>> for most of my testing. >>> >>> >>> Run some CPU stressor and get all your CPU's going at 100% load. >>> And watch your core temperatures while you do so. >> >> >> for i in 1 2 3 4; do while : ; do : ; done & done >> >> triggered the fault in a few minutes. >>> >>> >>>> >>>>>> It also would be good to rule out the thermal throttling (as per >>>>>> the Srinivas' comments). >>> >>> >>> It is almost certainly thermal throttling, or similar causing >>> Clock modulation, of it seems 50%. >> >> >> While the infinite loops were running, the temps were: >> >> finger@linux-1t8h:~/rtlwifi_new> sensors >> coretemp-isa-0000 >> Adapter: ISA adapter >> Physical id 0: +83.0°C (high = +84.0°C, crit = +100.0°C) >> Core 0: +83.0°C (high = +84.0°C, crit = +100.0°C) >> Core 1: +74.0°C (high = +84.0°C, crit = +100.0°C) > > It looks like the trip point (high) temperature was exceeded causing > thermal throttling to kick in. > >> After the fault occurs, I get >> >> finger@linux-1t8h:~/rtlwifi_new> sensors >> coretemp-isa-0000 >> Adapter: ISA adapter >> Physical id 0: +44.0°C (high = +84.0°C, crit = +100.0°C) >> Core 0: +43.0°C (high = +84.0°C, crit = +100.0°C) >> Core 1: +41.0°C (high = +84.0°C, crit = +100.0°C) > > So after that it stays at 400 MHz forever, right? > >>>>>> >>>>>> For now, please tell me what's in >>>>>> /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_min_freq >>>>> >>>>> 800000 >>>> >>>> Your effective freq is lower than 800MHz. One of the possible reason is >>>> thermal throttling. >>>> >>>> What distro you are using? >>> >>> >>> And what make and model of LapTop? >> >> >> Toshiba Tecra A50-A with CPU Model: 6.60.3 "Intel(R) Core(TM) i7-4600M CPU @ >> 2.90GHz. That is a dual-core unit with hyperthreading. >> >> @Rafael: As I write this, the system has been running the infinite loop test >> for almost 5 hours with kernel 4.7. I will leave that running while I'm >> gone, but I am certain that it is OK. > > OK, and what temperatures do you see while doing this? finger@linux-1t8h:~/linux-2.6> sensors coretemp-isa-0000 Adapter: ISA adapter Physical id 0: +90.0°C (high = +84.0°C, crit = +100.0°C) Core 0: +90.0°C (high = +84.0°C, crit = +100.0°C) Core 1: +78.0°C (high = +84.0°C, crit = +100.0°C) Once again, the CPU temp is greater than the "high" value; however, the clock rate continues to hold near 3600 MHz. My laptop was inadvertently put to sleep while I was gone. I forgot to leave a note for my wife and she quieted the noisy cpu fan. :) Larry