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=-6.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 350A5C433EF for ; Fri, 17 Sep 2021 03:33:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0BEF6610E9 for ; Fri, 17 Sep 2021 03:33:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241032AbhIQDeh (ORCPT ); Thu, 16 Sep 2021 23:34:37 -0400 Received: from mail.kernel.org ([198.145.29.99]:55036 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232440AbhIQDeh (ORCPT ); Thu, 16 Sep 2021 23:34:37 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9984B61056; Fri, 17 Sep 2021 03:33:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1631849595; bh=Q9PGtU5xvpxOOFAIBeN38KDl83cB2YIXJ+mu/SnJDUo=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=bkXzkfwOGHvzs27DtLCuvclKLhbyfIft2aoHfdly7VwN+kQCfcBU1e69naYIX5kcd y8r0Ny3F97DpN06jU+4bz3GAzQzx/EnURemOWq0N8KjHK+KJN1KWBqvGFmPXAS6KcP CBUVQQVz5Nt4HlSEhpizojqo/87rNk9gCDTAVMufs0pxTFq/9zF6soPEPolrQqeFv0 XEKhC4RHLm7XjfDRtgy3JXJFJgnjOK/BpQNA9n1dgRgCmG6kuDwv6Clupw4X7ZlVif z2XoMKdmZ6au0IiP9pb5LWoyrMg6aIpQmkolrPJdweQHqMXYtYkK2mmt0Ze5JNJti5 vthwAOCIbl2Yw== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 704D45C08DB; Thu, 16 Sep 2021 20:33:15 -0700 (PDT) Date: Thu, 16 Sep 2021 20:33:15 -0700 From: "Paul E. McKenney" To: Jakub Kicinski Cc: Bjorn Helgaas , x86@kernel.org, jose.souza@intel.com, hpa@zytor.com, bp@alien8.de, mingo@redhat.com, tglx@linutronix.de, kai.heng.feng@canonical.com, bhelgaas@google.com, linux-pci@vger.kernel.org, rudolph@fb.com, xapienz@fb.com, bmilton@fb.com, stable@vger.kernel.org Subject: Re: [PATCH] x86/intel: Disable HPET on another Intel Coffee Lake platform Message-ID: <20210917033315.GO4156@paulmck-ThinkPad-P17-Gen-1> Reply-To: paulmck@kernel.org References: <20210916131739.1260552-1-kuba@kernel.org> <20210916150707.GA1611532@bjorn-Precision-5520> <20210916083042.5f63163a@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> <20210916163547.GD4156@paulmck-ThinkPad-P17-Gen-1> <20210916195713.289a7889@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210916195713.289a7889@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Thu, Sep 16, 2021 at 07:57:13PM -0700, Jakub Kicinski wrote: > On Thu, 16 Sep 2021 09:35:47 -0700 Paul E. McKenney wrote: > > > > How did you pick v5.13? force_disable_hpet() was added by > > > > 62187910b0fc ("x86/intel: Add quirk to disable HPET for the Baytrail > > > > platform"), which appeared in v3.15. > > > > > > Erm, good question, it started happening for me (and others with the > > > same laptop) with v5.13. I just sort of assumed it was 2e27e793e280 > > > ("clocksource: Reduce clocksource-skew threshold"). > > > > > > It usually takes a day to repro (4 hours was the quickest repro I've > > > seen) so bisection was kind of out of question. > > > > OK, so this is an intermittent condition where HPET is sometimes slow to > > access for a short period of time? If that is the case, my thought is > > to set the clocksource to be reinitialized (without a splat and without > > marking the clocksource unstable), and to splat (and mark the clocksource > > unstable) if it is not get a good read after 100 subsequent attempts. > > > > So as long as the period of slowness lasts for less than 50 seconds, > > things would work fine. > > > > Seem reasonable? > > Could well be. Initially I thought it was suspend/resume related, then > I looked closer and it did happen mostly after resume... but anywhere > between 20 minutes to few hours after the resume. > > I'm here to test less crude patches but since that may take some time > I'd hope we can get this merged and into stable ASAP. Hopefully it can > make it to 5.13 while that branch is alive and into Fedora. It really > makes Coffee Lake machines pretty much unusable. Indeed, I could see where your reproducer is at best rather annoying. But a good data point for me either way, so thank you! Thanx, Paul