From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751663AbdGYWjV (ORCPT ); Tue, 25 Jul 2017 18:39:21 -0400 Received: from mail-pg0-f50.google.com ([74.125.83.50]:38038 "EHLO mail-pg0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751625AbdGYWjT (ORCPT ); Tue, 25 Jul 2017 18:39:19 -0400 Subject: Re: [PATCH 2/2] printk: Add boottime and real timestamps To: Peter Zijlstra , Prarit Bhargava Cc: linux-kernel@vger.kernel.org, Jonathan Corbet , Petr Mladek , Sergey Senozhatsky , 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 , Geert Uytterhoeven , "Luis R. Rodriguez" , Nicholas Piggin , "Jason A. Donenfeld" , Olof Johansson , "Theodore Ts'o" , Josh Poimboeuf , linux-doc@vger.kernel.org References: <1500985047-23038-1-git-send-email-prarit@redhat.com> <1500985047-23038-3-git-send-email-prarit@redhat.com> <20170725130034.jxcqrosqcrhw3shm@hirez.programming.kicks-ass.net> From: Mark Salyzyn Message-ID: <3ac0a334-6779-535a-dfe1-086ae7333bda@android.com> Date: Tue, 25 Jul 2017 15:39:16 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.1 MIME-Version: 1.0 In-Reply-To: <20170725130034.jxcqrosqcrhw3shm@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/25/2017 06:00 AM, Peter Zijlstra wrote: > On Tue, Jul 25, 2017 at 08:17:27AM -0400, Prarit Bhargava wrote: >> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug >> index 5b1662ec546f..6cd38a25f8ea 100644 >> --- a/lib/Kconfig.debug >> +++ b/lib/Kconfig.debug >> @@ -1,8 +1,8 @@ >> menu "printk and dmesg options" >> >> config PRINTK_TIME >> - int "Show timing information on printks (0-1)" >> - range 0 1 >> + int "Show timing information on printks (0-3)" >> + range 0 3 >> default "0" >> depends on PRINTK >> help >> @@ -13,7 +13,8 @@ config PRINTK_TIME >> The timestamp is always recorded internally, and exported >> to /dev/kmsg. This flag just specifies if the timestamp should >> be included, not that the timestamp is recorded. 0 disables the >> - timestamp and 1 uses the local clock. >> + timestamp and 1 uses the local clock, 2 uses the monotonic clock, and >> + 3 uses real clock. >> >> The behavior is also controlled by the kernel command line >> parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst > > choice > prompt "printk default clock" > default PRIMTK_TIME_DISABLE > help > goes here > > config PRINTK_TIME_DISABLE > bool "Disabled" > help > goes here > > config PRINTK_TIME_LOCAL > bool "local clock" > help > goes here > > config PRINTK_TIME_MONO > bool "CLOCK_MONOTONIC" > help > goes here > > config PRINTK_TIME_REAL > bool "CLOCK_REALTIME" > help > goes here > > endchoice > > config PRINTK_TIME > int > default 0 if PRINTK_TIME_DISABLE > default 1 if PRINTK_TIME_LOCAL > default 2 if PRINTK_TIME_MONO > default 3 if PRINTK_TIME_REAL > > > Although I must strongly discourage using REALTIME, DST will make > untangling your logs an absolute nightmare. I would simply not provide > it. I agree with using select, ensures only valid values are landed. It does mean that CONFIG_PRINTK_TIME in-effect gets deprecated. REALTIME is always UTC in the kernel. What about BOOTTIME? -- Mark