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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 00A4DC77B75 for ; Mon, 22 May 2023 16:12:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234516AbjEVQMV (ORCPT ); Mon, 22 May 2023 12:12:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56898 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233770AbjEVQMT (ORCPT ); Mon, 22 May 2023 12:12:19 -0400 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 978D7B6 for ; Mon, 22 May 2023 09:12:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=3Kof4Ubyf4S7Z31yQZ2w4xYy+/GOvsdXgqUlhiAJQaw=; b=q4+StTJbdXWKDwrNRlP/N5Kss5 dQHUNe9SdQL+zR+DuM1TeJh/aEr+MJHta6JbLORfgkaiP8MWcI4zqYRT2LmCop/Kl6n58S4b7oiHc q+td9BM+L2mn6ez/DeF8GmxqaslCzI7C6+GfQmpUnQ+t/ojoMp7FDGQzZNlx6E02t7Rv3AIDU6NCc SPlSkxu9C8b0xgnurLe1VjuQXBUnn+3gMzDMF28ic5yCPA0+HaXag3/shZMOwOT9+o0JDvlzrO72w N6rzWKkOyYnzYaeQ+LuKU0unzoxYLMcZCs23FrxNY6eU8XHR3T794GFV9TRQ9CU7zxbGmY/d1ILTA WbMI2rHw==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.96 #2 (Red Hat Linux)) id 1q188f-0024R2-10; Mon, 22 May 2023 16:12:01 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 297B9300338; Mon, 22 May 2023 18:11:59 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 01C0A243487CE; Mon, 22 May 2023 18:11:58 +0200 (CEST) Date: Mon, 22 May 2023 18:11:58 +0200 From: Peter Zijlstra To: Feng Tang Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H . Peter Anvin" , paulmck@kernel.org, rui.zhang@intel.com, x86@kernel.org, linux-kernel@vger.kernel.org, bin.gao@intel.com Subject: Re: [PATCH RFC] x86/tsc: Make recalibration default on for TSC_KNOWN_FREQ cases Message-ID: <20230522161158.GA3330346@hirez.programming.kicks-ass.net> References: <20230522033018.1276836-1-feng.tang@intel.com> <87h6s4ye9b.ffs@tglx> <87zg5wwppa.ffs@tglx> <87pm6swi7z.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 22, 2023 at 11:20:15PM +0800, Feng Tang wrote: > And I don't understand the commit log: "On Intel GOLDMONT Atom SoC > TSC is the only reliable clocksource. We mark TSC reliable to avoid > watchdog on it." > > Clearly the Denventon I found today has both HPET and ACPI_PM timer: > > [root@dnv0 ~]# grep . /sys/devices/system/clocksource/clocksource0/* > /sys/devices/system/clocksource/clocksource0/available_clocksource:tsc hpet acpi_pm > /sys/devices/system/clocksource/clocksource0/current_clocksource:tsc > > The lscpu info is: > > Architecture: x86_64 > CPU op-mode(s): 32-bit, 64-bit > Address sizes: 39 bits physical, 48 bits virtual > Byte Order: Little Endian > CPU(s): 12 > On-line CPU(s) list: 0-11 > Vendor ID: GenuineIntel > BIOS Vendor ID: Intel(R) Corporation > Model name: Intel(R) Atom(TM) CPU C3850 @ 2.10GHz > BIOS Model name: Intel(R) Atom(TM) CPU C3850 @ 2.10GHz CPU @ 2.1GHz > BIOS CPU family: 43 > CPU family: 6 > Model: 95 > Thread(s) per core: 1 > Core(s) per socket: 12 > Socket(s): 1 > Stepping: 1 > > Maybe this cpu model (0x5F) has been used by some type of platforms > which has met the false alarm watchdog issue. It has them; but they are not *reliable*.