From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932588AbdCWAFM (ORCPT ); Wed, 22 Mar 2017 20:05:12 -0400 Received: from aserp1040.oracle.com ([141.146.126.69]:28625 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932530AbdCWAFC (ORCPT ); Wed, 22 Mar 2017 20:05:02 -0400 Subject: Re: [v1 0/9] Early boot time stamps for x86 To: Peter Zijlstra References: <1490214265-899964-1-git-send-email-pasha.tatashin@oracle.com> <20170322202712.5d6l7klwucnfhucm@hirez.programming.kicks-ass.net> Cc: x86@kernel.org, linux-kernel@vger.kernel.org, mingo@redhat.com, tglx@linutronix.de, hpa@zytor.com From: Pasha Tatashin Message-ID: Date: Wed, 22 Mar 2017 20:02:34 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <20170322202712.5d6l7klwucnfhucm@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset=windows-1252; format=flowed 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 On 2017-03-22 16:27, Peter Zijlstra wrote: > On Wed, Mar 22, 2017 at 04:24:16PM -0400, Pavel Tatashin wrote: >> Last week I sent out patches to enable early boot time stamp on SPARC, that >> work is now under review: >> http://www.spinics.net/lists/sparclinux/msg17372.html >> >> This is continuation for that work, but adding early boot time stamps >> support for x86 machines. > > *groan*, so we get an even bigger trainwreck when TSC is fscked? > Hi Peter, I am not sure what you mean. If tsc is not reliable, the worst case is that during early boot the timestamps won't be as accurate as the timestamps that are enabled once we initialize some other clock sources. In either way, if you look at the way I enabled early timestamps, it is really narrowed down to work only on modern hardware with stable tsc. (Nehalem and later) Thank you, Pasha