From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752302AbdKHTeI (ORCPT ); Wed, 8 Nov 2017 14:34:08 -0500 Received: from merlin.infradead.org ([205.233.59.134]:54106 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751716AbdKHTeH (ORCPT ); Wed, 8 Nov 2017 14:34:07 -0500 Date: Wed, 8 Nov 2017 20:33:52 +0100 From: Peter Zijlstra To: Steven Rostedt Cc: Abderrahmane Benbachir , linux-kernel@vger.kernel.org, mingo@redhat.com, mathieu.desnoyers@efficios.com, Thomas Gleixner Subject: Re: [RFC PATCH v2] ftrace: support very early function tracing Message-ID: <20171108193352.GM3326@worktop> References: <1510098245.14960.3.camel@polymtl.ca> <20171107211706.328d7dd0@gandalf.local.home> <20171108081058.GT3165@worktop.lehotels.local> <20171108110757.5ef58e53@gandalf.local.home> <20171108190727.GL3326@worktop> <20171108141907.38d7cdda@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171108141907.38d7cdda@gandalf.local.home> User-Agent: Mutt/1.5.22.1 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 08, 2017 at 02:19:07PM -0500, Steven Rostedt wrote: > On Wed, 8 Nov 2017 20:07:27 +0100 > Peter Zijlstra wrote: > > > Depends on how early you need things; ideally you'd be able to use the > > Well, he starts tracing at the entry of start_kernel(), would this > handle that? You'll have to run something first to initialize clocks in any case. He's calling native_calibrate_cpu() (which of course if completely broken for virt). So you might as well setup the sched_clock() infra properly.