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=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 36EEEC43381 for ; Wed, 27 Feb 2019 08:44:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 04311218D0 for ; Wed, 27 Feb 2019 08:44:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="CopY6rgC" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729733AbfB0Ion (ORCPT ); Wed, 27 Feb 2019 03:44:43 -0500 Received: from mail-pl1-f193.google.com ([209.85.214.193]:33735 "EHLO mail-pl1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726724AbfB0Ion (ORCPT ); Wed, 27 Feb 2019 03:44:43 -0500 Received: by mail-pl1-f193.google.com with SMTP id y10so7693627plp.0 for ; Wed, 27 Feb 2019 00:44:43 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=CazSiCwvaXGcQ7xAr/oeXhU6+vfboWDbWRjo4n2b04Y=; b=CopY6rgCOcPKAHf4nmBgxT9Oltl4zi2vioDFeTBeRjhOhwx1LbC5d7UkfmpqyVuw5y noMY2+7WkD3KP5AdXZWIs9sa7w1hduoaskXuYc3pSJXB5jstqJvGAQKh7Z6lCVM5Ilkb 9zObQSWGB/LYawWqXaq92CNFN7J44bC2A6nZvFJ09cmpEAp/cuUt2XZ04Yhitsjizq7I 6eda/eRsI5SvuVzBVWIF/KLSbsZN/7yKef2uEC9LvhXB8NsXMaU7JleyfvZgRgvWbBTQ 0VLKx/39mdLmfFdpXmXofSFs8SozfWfEpjD0C1ohwaSeNkZlQmHfEmdTKg0EEAzq//VU is5Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=CazSiCwvaXGcQ7xAr/oeXhU6+vfboWDbWRjo4n2b04Y=; b=nOevj6c9CquumdLyOR2mUQHNc8llWaucT2IwjZ9DkVQGxohE9QyIezaRTnXe5C3s6+ Rk1nesSyi3D2lMbyL/12+h3Porkkls2CmGGeD/84drmxx350/5AwA4detVOgRxnnmN/2 2GXWWr3rim+lYTJBSEb2X8KZ4I9el8fdItM/1diB0jyFo/OmG1cjp2Kdp6of6tTNi5Xk iYR1eINHkF/3uDAM1sTFrl9ELiAvLsx6Dq6TZvUfAUAAzsUGsx+ew/5/onPGjcO3VHRO 8iQxpT+PhAwRLF5aDQUDDF80/iY8Jn+SL7sC/8FTZC1J9K13OGh2AaeXuuqtFmgaaEmD eNfA== X-Gm-Message-State: AHQUAuYPckJ7Yp5lDu8dV/W9LzimRKyS+258yzsU3asH2eD0ccOR49Ao xewLxRFG2rcqbBX1lZeLjKM= X-Google-Smtp-Source: AHgI3IYaeM4TnuILcIrgQOw1TD4eBoXpg+RQpaQ3hU7XB8XHKXC8CTYJkhPV7nB8ELFJvbX3D0dgjA== X-Received: by 2002:a17:902:6a4:: with SMTP id 33mr974472plh.233.1551257082710; Wed, 27 Feb 2019 00:44:42 -0800 (PST) Received: from localhost ([175.223.3.190]) by smtp.gmail.com with ESMTPSA id j68sm31567687pfc.64.2019.02.27.00.44.41 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 27 Feb 2019 00:44:41 -0800 (PST) Date: Wed, 27 Feb 2019 17:44:38 +0900 From: Sergey Senozhatsky To: John Ogness Cc: Sergey Senozhatsky , Petr Mladek , Sergey Senozhatsky , Steven Rostedt , linux-kernel@vger.kernel.org Subject: Re: [PATCH] printk/console: Do not suppress information about dropped messages Message-ID: <20190227084438.GA14252@jagdpanzerIV> References: <20190226124945.7078-1-pmladek@suse.com> <87k1hmzfam.fsf@linutronix.de> <20190227025559.GA18340@jagdpanzerIV> <87fts9fy5n.fsf@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87fts9fy5n.fsf@linutronix.de> User-Agent: Mutt/1.11.3 (2019-02-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (02/27/19 09:12), John Ogness wrote: > >> > >> My only objection to this is that the "messages dropped" only comes if a > >> non-supressed message comes. So information about dropped information > >> may never get printed unless some task prints something non-supressed. > >> > >> Imagine a situation where I am expecting a message to come, but don't > >> see it because it was dropped. But if no more non-supressed messages > >> come, I see neither the expected message nor the dropped message. > > > > I think this is exactly the problem (and thus the patch) we discussed > > some 3 years ago. > > I guess you are referring to this [0] thread. Right. [..] > I would agree with the proposed solution from 2016. My experience is > that the dropped messages are very important. Yes, printing them could > lead to the loss of even more messages. Yes, printing out messages does take time. But I think it's easier to start losing messages due to preemption under console_sem than due to call_console_drivers() latencies. > But still, it is important information that needs to get out. I'd agree. A summary "you lost %d messages somewhere between current and previous messages" is surely better than what we have now, but is still a bit less informative than "you lost %d messages just now". -ss