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_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 CA3D9C468C6 for ; Thu, 19 Jul 2018 16:20:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 83DA620661 for ; Thu, 19 Jul 2018 16:20:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 83DA620661 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linutronix.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732091AbeGSREQ (ORCPT ); Thu, 19 Jul 2018 13:04:16 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:33623 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731888AbeGSREQ (ORCPT ); Thu, 19 Jul 2018 13:04:16 -0400 Received: from p4fea5a5a.dip0.t-ipconnect.de ([79.234.90.90] helo=nanos) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1fgBeQ-00032V-2N; Thu, 19 Jul 2018 18:19:34 +0200 Date: Thu, 19 Jul 2018 18:19:33 +0200 (CEST) From: Thomas Gleixner To: Pavel Tatashin cc: Peter Zijlstra , steven.sistare@oracle.com, daniel.m.jordan@oracle.com, linux@armlinux.org.uk, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, john.stultz@linaro.org, sboyd@codeaurora.org, x86@kernel.org, linux-kernel@vger.kernel.org, mingo@redhat.com, hpa@zytor.com, douly.fnst@cn.fujitsu.com, prarit@redhat.com, feng.tang@intel.com, pmladek@suse.com, gnomes@lxorguk.ukuu.org.uk, linux-s390@vger.kernel.org, boris.ostrovsky@oracle.com, jgross@suse.com, pbonzini@redhat.com Subject: Re: [PATCH v14 20/25] x86/tsc: calibrate tsc only once In-Reply-To: <4295075b-8a0f-1723-2e80-1bbd2f038846@oracle.com> Message-ID: References: <20180718022211.6259-1-pasha.tatashin@oracle.com> <20180718022211.6259-21-pasha.tatashin@oracle.com> <20180719103340.GA2494@hirez.programming.kicks-ass.net> <4295075b-8a0f-1723-2e80-1bbd2f038846@oracle.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, 19 Jul 2018, Pavel Tatashin wrote: > On 07/19/2018 07:01 AM, Thomas Gleixner wrote: > > And hpet_pmtime_calibrate_cpu() contains all the hpet/pmtime stuff. > > However, when cpu_khz = x86_platform.calibrate_cpu() is called the first > time, we still call hpet_pmtime_calibrate_cpu() from > native_calibrate_cpu(). We cannot simply split native_calibrate_cpu() > into two independent functions because it is also called from > recalibrate_cpu_khz(). > So, the question is how to enforce that the first time we do not call hpet/pmtime? > > 1. Use a new global variable? Kind of ugly. > 2. Use system_state == SYSTEM_BOOTING ? Ugly, and probably not very safe. Both are horrible. So create two functions. native_...early..() and native....(). The early one does not contain the hpet/pmtimer stuff and it replaces the ops.pointer with the late one which contains all of it. Hmm? Thanks, tglx