Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752910AbdI0NRQ (ORCPT ); Wed, 27 Sep 2017 09:17:16 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:30968 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752282AbdI0NRO (ORCPT ); Wed, 27 Sep 2017 09:17:14 -0400 Subject: Re: [PATCH v6 1/4] sched/clock: interface to allow timestamps early in boot To: Peter Zijlstra Cc: 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, tglx@linutronix.de, hpa@zytor.com, douly.fnst@cn.fujitsu.com References: <1504116205-355281-1-git-send-email-pasha.tatashin@oracle.com> <1504116205-355281-2-git-send-email-pasha.tatashin@oracle.com> <20170927125857.yvwefpejzskiduwu@hirez.programming.kicks-ass.net> <20170927131003.dxbvu7frcqgtiwaz@hirez.programming.kicks-ass.net> From: Pasha Tatashin Message-ID: Date: Wed, 27 Sep 2017 09:16:00 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 MIME-Version: 1.0 In-Reply-To: <20170927131003.dxbvu7frcqgtiwaz@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Source-IP: userv0022.oracle.com [156.151.31.74] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 589 Lines: 18 Hi Peter, I am totally happy with removing notsc. This certainly simplifies the sched_clock code. Are there any issues with removing existing kernel parameters that I should be aware of? Thank you, Pasha On 09/27/2017 09:10 AM, Peter Zijlstra wrote: > On Wed, Sep 27, 2017 at 02:58:57PM +0200, Peter Zijlstra wrote: >> (we're violating "notsc" in any case and really should kill that >> option). > > Something like so; in particular simple_udelay_calibrate() will issue > RDTSC _way_ early, so there is absolutely no point in then pretending we > can't use RDTSC for sched_clock. >