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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 8B42EC4321A for ; Tue, 11 Jun 2019 20:11:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4F8FD21734 for ; Tue, 11 Jun 2019 20:11:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2406133AbfFKULV (ORCPT ); Tue, 11 Jun 2019 16:11:21 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:59543 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405799AbfFKULU (ORCPT ); Tue, 11 Jun 2019 16:11:20 -0400 Received: from p5b06daab.dip0.t-ipconnect.de ([91.6.218.171] helo=nanos) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1han6o-0004fr-IZ; Tue, 11 Jun 2019 22:11:06 +0200 Date: Tue, 11 Jun 2019 22:11:04 +0200 (CEST) From: Thomas Gleixner To: Ricardo Neri cc: Ingo Molnar , Borislav Petkov , Ashok Raj , Joerg Roedel , Andi Kleen , Peter Zijlstra , Suravee Suthikulpanit , Stephane Eranian , "Ravi V. Shankar" , Randy Dunlap , x86@kernel.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Ricardo Neri , Tony Luck , Jacob Pan , "Rafael J. Wysocki" , Don Zickus , Nicholas Piggin , Michael Ellerman , Frederic Weisbecker , Alexei Starovoitov , Babu Moger , Mathieu Desnoyers , Masami Hiramatsu , Andrew Morton , Philippe Ombredanne , Colin Ian King , Byungchul Park , "Paul E. McKenney" , "Luis R. Rodriguez" , Waiman Long , Josh Poimboeuf , Davidlohr Bueso , Marc Zyngier , Kai-Heng Feng , Konrad Rzeszutek Wilk , David Rientjes Subject: Re: [RFC PATCH v4 12/21] watchdog/hardlockup/hpet: Adjust timer expiration on the number of monitored CPUs In-Reply-To: <1558660583-28561-13-git-send-email-ricardo.neri-calderon@linux.intel.com> Message-ID: References: <1558660583-28561-1-git-send-email-ricardo.neri-calderon@linux.intel.com> <1558660583-28561-13-git-send-email-ricardo.neri-calderon@linux.intel.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 23 May 2019, Ricardo Neri wrote: > @@ -52,10 +59,10 @@ static void kick_timer(struct hpet_hld_data *hdata, bool force) > return; > > if (hdata->has_periodic) > - period = watchdog_thresh * hdata->ticks_per_second; > + period = watchdog_thresh * hdata->ticks_per_cpu; > > count = hpet_readl(HPET_COUNTER); > - new_compare = count + watchdog_thresh * hdata->ticks_per_second; > + new_compare = count + watchdog_thresh * hdata->ticks_per_cpu; > hpet_set_comparator(hdata->num, (u32)new_compare, (u32)period); So with this you might get close to the point where you trip over the SMI induced madness where CPUs vanish for several milliseconds in some value add code. You really want to do a read back of the hpet to detect that. See the comment in the hpet code. RHEL 7/8 allow up to 768 logical CPUs.... Thanks, tglx