From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751671AbdISLwj (ORCPT ); Tue, 19 Sep 2017 07:52:39 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36456 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751458AbdISLwh (ORCPT ); Tue, 19 Sep 2017 07:52:37 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 09EED2F9469 Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=prarit@redhat.com Subject: Re: [PATCH 3/3 v11] printk: Add monotonic, boottime, and realtime timestamps To: Sergey Senozhatsky , Mark Salyzyn , Petr Mladek References: <1504613201-23868-1-git-send-email-prarit@redhat.com> <1504613201-23868-4-git-send-email-prarit@redhat.com> <20170915132808.GL2908@pathway.suse.cz> <4cf75f3b-7d46-9e6c-3929-881f013f1c77@android.com> <20170917104634.GA442@tigerII.localdomain> Cc: linux-kernel@vger.kernel.org, Jonathan Corbet , Steven Rostedt , John Stultz , Thomas Gleixner , Stephen Boyd , Andrew Morton , Greg Kroah-Hartman , "Paul E. McKenney" , Christoffer Dall , Deepa Dinamani , Ingo Molnar , Joel Fernandes , Kees Cook , Peter Zijlstra , Geert Uytterhoeven , "Luis R. Rodriguez" , Nicholas Piggin , "Jason A. Donenfeld" , Olof Johansson , Josh Poimboeuf , linux-doc@vger.kernel.org From: Prarit Bhargava Message-ID: <5cd0541d-148c-b131-076a-910f8a900770@redhat.com> Date: Tue, 19 Sep 2017 07:52:33 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 MIME-Version: 1.0 In-Reply-To: <20170917104634.GA442@tigerII.localdomain> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Tue, 19 Sep 2017 11:52:37 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/17/2017 06:46 AM, Sergey Senozhatsky wrote: > I'm a bit uncomfortable with the "breaks user space" part. since this > is a strictly debugging option, would it be sufficient to store those > extended timestamps as prefixes of every message? > see (sorry for "self-quoting"): > lkml.kernel.org/r/20170917062608.GA512@tigerII.localdomain > Sergey, I haven't forgotten about the above. It's something I'm going to look at after this initial patchset is done. P. > each message, thus, will be in the following format > > [current header: loglevel, timestamp, etc] [extended printk data] message text > > extended printk data can contain your monotonic/etc timestamps, and > anything else. > > and then it's up to you how do you grep the messages and process the > extended data. but the point is - user space tools (journald, dmesg, > etc.) stays intact. which is kinda nice. > > so we can avoid that chicken and egg problem: we break user space > by merging the patchset but user space people don't want to talk > about any fixes until we break those tools. > > -ss >