From mboxrd@z Thu Jan 1 00:00:00 1970 From: bugzilla-daemon@bugzilla.kernel.org Subject: [Bug 173361] Under heavy load, the CPU speed suddenly and irreversibly drops from 3500 to 400 MHz Date: Thu, 29 Sep 2016 16:40:29 +0000 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Return-path: Received: from mail.kernel.org ([198.145.29.136]:37374 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753890AbcI2Qkc (ORCPT ); Thu, 29 Sep 2016 12:40:32 -0400 Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 33BB62038E for ; Thu, 29 Sep 2016 16:40:31 +0000 (UTC) Received: from bugzilla2.web.kernel.org (bugzilla2.web.kernel.org [172.20.200.52]) by mail.kernel.org (Postfix) with ESMTP id 1CE0B20260 for ; Thu, 29 Sep 2016 16:40:30 +0000 (UTC) In-Reply-To: Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: linux-pm@vger.kernel.org https://bugzilla.kernel.org/show_bug.cgi?id=173361 Doug Smythies changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |dsmythies@telus.net --- Comment #1 from Doug Smythies --- For what it is worth, some data from my computer: . I get the exact same steady state temperature and package power under full load with both kernel 4.7 and 4.8-rc8. . I messed with the cooling so that it could exceed the high limit, and when it did nothing tripped (as expected): doug@s15:~/temp2$ sensors coretemp-isa-0000 Adapter: ISA adapter Physical id 0: +81.0°C (high = +80.0°C, crit = +98.0°C) Core 0: +77.0°C (high = +80.0°C, crit = +98.0°C) Core 1: +81.0°C (high = +80.0°C, crit = +98.0°C) Core 2: +77.0°C (high = +80.0°C, crit = +98.0°C) Core 3: +78.0°C (high = +80.0°C, crit = +98.0°C) For this comment from the e-mail thread: "Hmm, I would not expect the CPU to drop from 80 to 40 degrees in a few seconds if the fan is not spinning. I wouldn't even expect it if the fan was spinning. I would think at least 30 to 60 seconds if not more." I from a steady state, full load, temperature of 78 degrees C to 0 load I see: 15 degrees drop in 1 second; 18 degrees drop in 2 seconds; 22 degrees drop in 10 seconds; 25 degrees droop in 20 seconds. For the original post comment: "In that case, the bug would be that the frequency is never restored." It isn't supposed to restore. I do not know why in this case it is kicking in at 50%, usually it is less. Regardless, the current control algorithm in the intel_pstate driver is fundamentally incompatible with clock modulation, and will always drive the CPU down to the minimum * the modulation %, regardless of load. Other drivers typically drive the CPU frequency to what would normally be desired * modulation % (and for the most part users don't even notice). -- You are receiving this mail because: You are the assignee for the bug.