Delivered-To: jwboyer@gmail.com Received: by 10.76.27.197 with SMTP id v5csp2271oag; Thu, 23 Jan 2014 01:54:21 -0800 (PST) X-Received: by 10.66.136.131 with SMTP id qa3mr7006698pab.77.1390470860654; Thu, 23 Jan 2014 01:54:20 -0800 (PST) Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id qv10si13378362pbb.142.2014.01.23.01.53.38 for ; Thu, 23 Jan 2014 01:54:20 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mail=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751970AbaAWJsq (ORCPT + 99 others); Thu, 23 Jan 2014 04:48:46 -0500 Received: from merlin.infradead.org ([205.233.59.134]:55711 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751445AbaAWJso (ORCPT ); Thu, 23 Jan 2014 04:48:44 -0500 Received: from dhcp-077-248-225-117.chello.nl ([77.248.225.117] helo=twins) by merlin.infradead.org with esmtpsa (Exim 4.80.1 #2 (Red Hat Linux)) id 1W6GtY-00025n-Ny; Thu, 23 Jan 2014 09:48:21 +0000 Received: by twins (Postfix, from userid 1000) id 0B4E580383F6; Thu, 23 Jan 2014 10:48:04 +0100 (CET) Date: Thu, 23 Jan 2014 10:48:04 +0100 From: Peter Zijlstra To: Markus Trippelsdorf Cc: Sasha Levin , Arjan van de Ven , lenb@kernel.org, rjw@rjwysocki.net, Eliezer Tamir , rui.zhang@intel.com, jacob.jun.pan@linux.intel.com, Mike Galbraith , Ingo Molnar , hpa@zytor.com, paulmck@linux.vnet.ibm.com, Thomas Gleixner , John Stultz , Andy Lutomirski , linux-kernel@vger.kernel.org, dyoung@redhat.com Subject: Re: [PATCH 13/15] sched: Use a static_key for sched_clock_stable Message-ID: <20140123094804.GP30183@twins.programming.kicks-ass.net> References: <20140122123022.GN31570@twins.programming.kicks-ass.net> <20140122131456.GA389@x4> <52DFD50E.800@oracle.com> <20140122183538.GA389@x4> <20140122184253.GN30183@twins.programming.kicks-ass.net> <20140122190905.GA391@x4> <20140122191254.GA390@x4> <20140122201605.GU11314@laptop.programming.kicks-ass.net> <20140122210814.GC9481@laptop.programming.kicks-ass.net> <20140122211740.GA391@x4> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140122211740.GA391@x4> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 22, 2014 at 10:17:40PM +0100, Markus Trippelsdorf wrote: > Yes. Thanks Peter. > Ah much simpler patch that should have the same effect: --- Subject: sched/x86/tsc: Initialize multiplier to 0 From: Peter Zijlstra Date: Wed, 22 Jan 2014 22:08:14 +0100 Since we keep the clock value linearly continuous on frequency change, make sure the initial multiplier is 0, such that out initial value is 0. Without this we compute the initial value at whatever the TSC has managed to reach since power-on. Fixes: 20d1c86a57762 ("sched/clock, x86: Rewrite cyc2ns() to avoid the need to disable IRQs") Cc: lenb@kernel.org Cc: rjw@rjwysocki.net Cc: Eliezer Tamir Cc: rui.zhang@intel.com Cc: jacob.jun.pan@linux.intel.com Cc: Mike Galbraith Cc: Ingo Molnar Cc: hpa@zytor.com Cc: paulmck@linux.vnet.ibm.com Cc: Thomas Gleixner Cc: John Stultz Cc: Andy Lutomirski Cc: Arjan van de Ven Cc: Sasha Levin Cc: dyoung@redhat.com Reported-by: Markus Trippelsdorf Signed-off-by: Peter Zijlstra --- arch/x86/kernel/tsc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -180,7 +180,7 @@ static void cyc2ns_write_end(int cpu, st static void cyc2ns_data_init(struct cyc2ns_data *data) { - data->cyc2ns_mul = 1U << CYC2NS_SCALE_FACTOR; + data->cyc2ns_mul = 0; data->cyc2ns_shift = CYC2NS_SCALE_FACTOR; data->cyc2ns_offset = 0; data->__count = 0; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/