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 B5656C433E0 for ; Fri, 1 Jan 2021 10:12:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7890F21E92 for ; Fri, 1 Jan 2021 10:12:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726469AbhAAKM3 convert rfc822-to-8bit (ORCPT ); Fri, 1 Jan 2021 05:12:29 -0500 Received: from mail.kernel.org ([198.145.29.99]:55364 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726462AbhAAKM3 (ORCPT ); Fri, 1 Jan 2021 05:12:29 -0500 Received: by mail.kernel.org (Postfix) with ESMTPS id EDC0321E92 for ; Fri, 1 Jan 2021 10:11:48 +0000 (UTC) From: bugzilla-daemon@bugzilla.kernel.org To: linux-pm@vger.kernel.org Subject: [Bug 210993] New: Intel frequency scaling causes electrical noise on 10th gen CPUs Date: Fri, 01 Jan 2021 10:11:48 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: new 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: NEW X-Bugzilla-Resolution: X-Bugzilla-Priority: P1 X-Bugzilla-Assigned-To: linux-pm@vger.kernel.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: bug_id short_desc product version cf_kernel_version rep_platform op_sys cf_tree bug_status bug_severity priority component assigned_to reporter cf_regression Message-ID: 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 Bug ID: 210993 Summary: Intel frequency scaling causes electrical noise on 10th gen CPUs Product: Power Management Version: 2.5 Kernel Version: 5.9.16 Hardware: Intel OS: Linux Tree: Mainline Status: NEW Severity: enhancement Priority: P1 Component: cpufreq Assignee: linux-pm@vger.kernel.org Reporter: karolherbst@gmail.com Regression: No One thing I noticed with my i7-10850H CPU is, that if there are cores with huge differences in their frequencies (e.g. one at 900 MHz another at 4.9 GHz) some electrical becomes noticable. The noise can be reduced by limiting the available range the CPUs frequency can be scaled to. Sadly the scaling_min_freq property is ignored outright and only matters as long as the CPU stays idle, but as long as one core gets some load, another one drops below scaling_min_freq, so I couldn't test if limiting the lower bound even helps. Putting one core at max load with stress -c 1 effectively eliminates all noise. This issue is even more annoying on my laptop as it generally runs with the fans turned off. intel_pstate is used in active mode, but putting it in passive mode, disabling HWP or even using the ACPI freq scaling didn't really change anything in this regard. The powersave governor and default energy_performance_preference is used. Is there anything else which could be done to mitigate the problem? Just putting a finger on the touchpad makes the noise quite noticeable as cores get scaled to the max. Thanks -- You may reply to this email to add a comment. You are receiving this mail because: You are the assignee for the bug.