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=-5.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT 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 1140BC43381 for ; Fri, 15 Mar 2019 12:30:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D3A9E21871 for ; Fri, 15 Mar 2019 12:30:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="Et69gAI1" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729003AbfCOMaG (ORCPT ); Fri, 15 Mar 2019 08:30:06 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:36848 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727671AbfCOMaF (ORCPT ); Fri, 15 Mar 2019 08:30:05 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; 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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=/Ckel4zvjLrhxvyqm3MFEjjHJgoBIPigW3uv5xckhjE=; b=Et69gAI1ytf+ehROyT4f/n7Ca TaZiomf07G4wk7y8LSQcY5hY7cH/tuVuC4kKEptJfXxFFPurIDzKaVkYpJxy9Wshb1qU3w5BsLi+V JrDXK5wfRPYYY/qlEJV426RG4HzZQOtPDezYgC/IAW+CUI/ch7UykyZfqjYX0yrkJcMo4zB/DOCv6 xdvC9/TNcGDjWtezXQHc0pSkuwhXUuaN4HTSGRKdAV3XxjAm/1zC9wwq/b5p+apvPTwB768WdBClO 3HuEmfXX1xQnw0/H5SM12jMTmtgejJfEI62uFjFCoKzdpxoReLXmFY0rdBBT7nYXia+AFNP35lNWW ppwQUTLrA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1h4lyD-0006bW-Uy; Fri, 15 Mar 2019 12:29:54 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 7693F21419E57; Fri, 15 Mar 2019 13:29:52 +0100 (CET) Date: Fri, 15 Mar 2019 13:29:52 +0100 From: Peter Zijlstra To: Viresh Kumar Cc: Rafael Wysocki , Russell King , "David S. Miller" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , x86@kernel.org, Paolo Bonzini , Radim =?utf-8?B?S3LEjW3DocWZ?= , linux-pm@vger.kernel.org, Vincent Guittot , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, sparclinux@vger.kernel.org, kvm@vger.kernel.org Subject: Re: [PATCH V2] cpufreq: Call transition notifier only once for each policy Message-ID: <20190315122952.GF6058@hirez.programming.kicks-ass.net> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 15, 2019 at 02:43:07PM +0530, Viresh Kumar wrote: > diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c > index 3fae23834069..cff8779fc0d2 100644 > --- a/arch/x86/kernel/tsc.c > +++ b/arch/x86/kernel/tsc.c > @@ -956,28 +956,38 @@ static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val, > void *data) > { > struct cpufreq_freqs *freq = data; > - unsigned long *lpj; > - > - lpj = &boot_cpu_data.loops_per_jiffy; > -#ifdef CONFIG_SMP > - if (!(freq->flags & CPUFREQ_CONST_LOOPS)) > - lpj = &cpu_data(freq->cpu).loops_per_jiffy; > -#endif > + struct cpumask *cpus = freq->policy->cpus; > + bool boot_cpu = !IS_ENABLED(CONFIG_SMP) || freq->flags & CPUFREQ_CONST_LOOPS; > + unsigned long lpj; > + int cpu; > > if (!ref_freq) { > ref_freq = freq->old; > - loops_per_jiffy_ref = *lpj; > tsc_khz_ref = tsc_khz; > + > + if (boot_cpu) > + loops_per_jiffy_ref = boot_cpu_data.loops_per_jiffy; > + else > + loops_per_jiffy_ref = cpu_data(cpumask_first(cpus)).loops_per_jiffy; > } > + > if ((val == CPUFREQ_PRECHANGE && freq->old < freq->new) || > (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) { > - *lpj = cpufreq_scale(loops_per_jiffy_ref, ref_freq, freq->new); > - > + lpj = cpufreq_scale(loops_per_jiffy_ref, ref_freq, freq->new); > tsc_khz = cpufreq_scale(tsc_khz_ref, ref_freq, freq->new); > + > if (!(freq->flags & CPUFREQ_CONST_LOOPS)) > mark_tsc_unstable("cpufreq changes"); > > - set_cyc2ns_scale(tsc_khz, freq->cpu, rdtsc()); > + if (boot_cpu) { > + boot_cpu_data.loops_per_jiffy = lpj; > + } else { > + for_each_cpu(cpu, cpus) > + cpu_data(cpu).loops_per_jiffy = lpj; > + } > + > + for_each_cpu(cpu, cpus) > + set_cyc2ns_scale(tsc_khz, cpu, rdtsc()); This code doesn't make sense, the rdtsc() _must_ be called on the CPU in question. That's part of the whole problem here, TSC isn't sync'ed when it's subject to CPUFREQ. > } > > return 0;