From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id D2F6EC14 for ; Tue, 20 Jun 2017 16:44:15 +0000 (UTC) Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 77AA6269 for ; Tue, 20 Jun 2017 16:44:15 +0000 (UTC) From: "Luck, Tony" To: Sergey Senozhatsky , Mark Brown Date: Tue, 20 Jun 2017 16:44:13 +0000 Message-ID: <3908561D78D1C84285E8C5FCA982C28F612DAC67@ORSMSX114.amr.corp.intel.com> References: <20170619052146.GA2889@jagdpanzerIV.localdomain> <20170619103912.2edbf88a@gandalf.local.home> <20170619152055.GM3786@lunn.ch> <01a7d603-c0a2-7aae-8c8d-587063da5e61@suse.com> <20170619162317.4nxx6jsvuzvdtasz@sirena.org.uk> <20170620155825.GC409@tigerII.localdomain> In-Reply-To: <20170620155825.GC409@tigerII.localdomain> Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Cc: "ksummit-discuss@lists.linuxfoundation.org" Subject: Re: [Ksummit-discuss] [TECH TOPIC] printk redesign List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , >> This is a configuration option (PRINTK_TIME) and isn't 100% reliable, >> I've got examples in the syslog of my current system with multiple >> prints being issued with the same timestamp. > > yes, as far as I know, timestamps are not in complete sync between CPUs. We are pretty deep into the printk() code before we call local_clock() to find out what timestamp to print. Would it be helpful to grab that much earlier ... so it is closer to the time at which the code that called print= k()? This would make it more likely that messages would appear out of order, but I think it would be better to know when things actually happened, not when we got around to printing them. -Tony