From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=BAYES_00,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D749AC433E0 for ; Mon, 4 Jan 2021 22:39:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9D79122525 for ; Mon, 4 Jan 2021 22:39:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726520AbhADWjZ convert rfc822-to-8bit (ORCPT ); Mon, 4 Jan 2021 17:39:25 -0500 Received: from mail.kernel.org ([198.145.29.99]:50070 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726502AbhADWjY (ORCPT ); Mon, 4 Jan 2021 17:39:24 -0500 Received: by mail.kernel.org (Postfix) with ESMTPS id 4A6152253A for ; Mon, 4 Jan 2021 22:38:44 +0000 (UTC) From: bugzilla-daemon@bugzilla.kernel.org To: linux-pm@vger.kernel.org Subject: [Bug 210993] Intel frequency scaling causes electrical noise on 10th gen CPUs Date: Mon, 04 Jan 2021 22:38:44 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Power Management X-Bugzilla-Component: cpufreq X-Bugzilla-Version: 2.5 X-Bugzilla-Keywords: X-Bugzilla-Severity: enhancement X-Bugzilla-Who: karolherbst@gmail.com X-Bugzilla-Status: NEEDINFO X-Bugzilla-Resolution: X-Bugzilla-Priority: P1 X-Bugzilla-Assigned-To: linux-pm@vger.kernel.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT X-Bugzilla-URL: https://bugzilla.kernel.org/ Auto-Submitted: auto-generated MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org https://bugzilla.kernel.org/show_bug.cgi?id=210993 --- Comment #6 from Karol Herbst (karolherbst@gmail.com) --- (In reply to Francisco Jerez from comment #5) > O_o, that's really weird. I guess this could also be some sort of > electromagnetic interference (E.g. with your soundcard? Does the problem > occur with the loudspeakers turned off?), or an issue with your PSU. > It is very quiet. Definitely you can hear it only with slowly spinning fans and no background noise. Searching through the web it sounds like a common issue and disabling sleep states is supposed to be the proper "fix" for this. But at least muting the speakers don't help. > The apparent frequency dropping below scaling_min_freq might be an artifact > of how the busy frequency of a CPU thread is calculated: It should > approximate the ratio of executed clock cycles to the time it spent in C0 > state, which can deviate from its actual working frequency if the processor > enters and exits some C1+ state repeatedly since the transition may have > some significant latency. According to your turbostat log the CPU cores > that report a busy frequency below scaling_min_freq seem to be handling > quite a few interrupts which is consistent with that explanation. It > doesn't necessarily indicate a power management bug. > > Does disabling some specific idle state (e.g via > /sys/devices/system/cpu/cpu*/cpuidle/state*/disable) have any effect on the > noise? disabling all except state0 stops the noise. -- You may reply to this email to add a comment. You are receiving this mail because: You are the assignee for the bug.