From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx2.suse.de ([195.135.220.15]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1k6WM6-0007sl-JK for kexec@lists.infradead.org; Fri, 14 Aug 2020 09:50:35 +0000 Date: Fri, 14 Aug 2020 11:50:31 +0200 From: Petr Mladek Subject: Re: [RFC PATCH] printk: Change timestamp to triplet as mono, boot and real Message-ID: <20200814095031.GM6215@alley> References: <1597120822-11999-1-git-send-email-orsonzhai@gmail.com> <20200811094413.GA12903@alley> <87zh7175hj.fsf@nanos.tec.linutronix.de> <20200811130218.GI6215@alley> <20200813015500.GC2020879@jagdpanzerIV.localdomain> <20200813102258.GL12903@alley> <20200813113155.GA483@jagdpanzerIV.localdomain> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200813113155.GA483@jagdpanzerIV.localdomain> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Sergey Senozhatsky Cc: Prarit Bhargava , John Ogness , Orson Zhai , Baoquan He , cixi.geng1@unisoc.com, Stephen Boyd , zhang.lyra@gmail.com, Steven Sistare , kexec@lists.infradead.org, linux-kernel@vger.kernel.org, Steven Rostedt , Jon DeVree , John Stultz , ruifeng.zhang1@unisoc.com, Orson Zhai , Thomas Gleixner , Salvatore Bonaccorso , Dave Young , Dominique Martinet , Vivek Goyal , Pavel Tatashin On Thu 2020-08-13 20:31:55, Sergey Senozhatsky wrote: > On (20/08/13 12:22), Petr Mladek wrote: > > > > + would take more space (prefix + text vs. binary representation) > > Dict buffer is allocated regardless of how we use it, and only printks > from drivers/* (dev_printk*) add dict payload. It might be the case > that on some (if not most) systems dict pages are not used 90% of times > (if not 99%). > > > + not reliable because dict is currently dropped when no space > > Well, in the perfect world this is a problem, but "maybe not having > alternative timestamps sometimes" can be OK approach for people who > wants to use those triplet timestamps. I am afraid the people would see missing timestamps as a bug. They want it because they want to corelate kernel and userspace logs. The timestamps from realtime clock are supposed to make it straightforward. More importantly. I do not see a reasonable way how to handle it. No timestamp is worse than timestamps from non-synchronized clock. Mixing timestamps from different clocks (as fallback) would cause a lot of confusion (more harm than good). > But, in general, how real this problem is? What I sae so far (on my boxes) > was that printk messages are longer than dict payload. Yeah, I think that dict are less used on normal systems. But it might be very different when a driver gets more verbose during debugging and the amount of dev_printk() calls is much higher. Best Regards, Petr _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 83B9AC433DF for ; Fri, 14 Aug 2020 09:51:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6866C204EA for ; Fri, 14 Aug 2020 09:51:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726923AbgHNJuf (ORCPT ); Fri, 14 Aug 2020 05:50:35 -0400 Received: from mx2.suse.de ([195.135.220.15]:33078 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726064AbgHNJue (ORCPT ); Fri, 14 Aug 2020 05:50:34 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id DD077AD1B; Fri, 14 Aug 2020 09:50:55 +0000 (UTC) Date: Fri, 14 Aug 2020 11:50:31 +0200 From: Petr Mladek To: Sergey Senozhatsky Cc: Thomas Gleixner , Orson Zhai , Prarit Bhargava , Dave Young , Baoquan He , Vivek Goyal , Steven Rostedt , John Stultz , Stephen Boyd , kexec@lists.infradead.org, linux-kernel@vger.kernel.org, zhang.lyra@gmail.com, ruifeng.zhang1@unisoc.com, cixi.geng1@unisoc.com, Orson Zhai , Pavel Tatashin , Steven Sistare , Dominique Martinet , Jon DeVree , Salvatore Bonaccorso , John Ogness Subject: Re: [RFC PATCH] printk: Change timestamp to triplet as mono, boot and real Message-ID: <20200814095031.GM6215@alley> References: <1597120822-11999-1-git-send-email-orsonzhai@gmail.com> <20200811094413.GA12903@alley> <87zh7175hj.fsf@nanos.tec.linutronix.de> <20200811130218.GI6215@alley> <20200813015500.GC2020879@jagdpanzerIV.localdomain> <20200813102258.GL12903@alley> <20200813113155.GA483@jagdpanzerIV.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200813113155.GA483@jagdpanzerIV.localdomain> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 2020-08-13 20:31:55, Sergey Senozhatsky wrote: > On (20/08/13 12:22), Petr Mladek wrote: > > > > + would take more space (prefix + text vs. binary representation) > > Dict buffer is allocated regardless of how we use it, and only printks > from drivers/* (dev_printk*) add dict payload. It might be the case > that on some (if not most) systems dict pages are not used 90% of times > (if not 99%). > > > + not reliable because dict is currently dropped when no space > > Well, in the perfect world this is a problem, but "maybe not having > alternative timestamps sometimes" can be OK approach for people who > wants to use those triplet timestamps. I am afraid the people would see missing timestamps as a bug. They want it because they want to corelate kernel and userspace logs. The timestamps from realtime clock are supposed to make it straightforward. More importantly. I do not see a reasonable way how to handle it. No timestamp is worse than timestamps from non-synchronized clock. Mixing timestamps from different clocks (as fallback) would cause a lot of confusion (more harm than good). > But, in general, how real this problem is? What I sae so far (on my boxes) > was that printk messages are longer than dict payload. Yeah, I think that dict are less used on normal systems. But it might be very different when a driver gets more verbose during debugging and the amount of dev_printk() calls is much higher. Best Regards, Petr