From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756933Ab0KJVeh (ORCPT ); Wed, 10 Nov 2010 16:34:37 -0500 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.124]:50283 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756142Ab0KJVeg (ORCPT ); Wed, 10 Nov 2010 16:34:36 -0500 X-Authority-Analysis: v=1.1 cv=6ptpMFIBtxRk0xdOb6IhJTbTLVRlKjWFes7R4SsWCrA= c=1 sm=0 a=0Gcdu3wDtgIA:10 a=Q9fys5e9bTEA:10 a=OPBmh+XkhLl+Enan7BmTLg==:17 a=G1koFLn1gv4A7iRKHjMA:9 a=e_l8eaHGDtHmwEckP8QPlvm7O2UA:4 a=PUjeQqilurYA:10 a=OPBmh+XkhLl+Enan7BmTLg==:117 X-Cloudmark-Score: 0 X-Originating-IP: 67.242.120.143 Subject: RE: Tracing Requirements (was: [RFC/Requirements/Design] h/w error reporting) From: Steven Rostedt To: "Luck, Tony" Cc: Mathieu Desnoyers , Frederic Weisbecker , Ingo Molnar , Peter Zijlstra , "linux-kernel@vger.kernel.org" , "Huang, Ying" , "bp@alien8.de" , "tglx@linutronix.de" , "akpm@linux-foundation.org" , "mchehab@redhat.com" , Arnaldo Carvalho de Melo , Arjan van de Ven In-Reply-To: <1289423194.12418.195.camel@gandalf.stny.rr.com> References: <1289400056.12418.139.camel@gandalf.stny.rr.com> <1289400234.2191.129.camel@laptop> <1289401781.12418.145.camel@gandalf.stny.rr.com> <1289403019.2084.17.camel@laptop> <20101110174852.GB4001@elte.hu> <1289412329.12418.177.camel@gandalf.stny.rr.com> <1289413460.2084.27.camel@laptop> <20101110184105.GH22410@elte.hu> <1289415645.12418.180.camel@gandalf.stny.rr.com> <20101110191127.GA6190@nowhere> <20101110202316.GA32396@Krystal> <987664A83D2D224EAE907B061CE93D5301649A71DC@orsmsx505.amr.corp.intel.com> <1289423194.12418.195.camel@gandalf.stny.rr.com> Content-Type: text/plain; charset="ISO-8859-15" Date: Wed, 10 Nov 2010 16:34:34 -0500 Message-ID: <1289424874.12418.199.camel@gandalf.stny.rr.com> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2010-11-10 at 16:06 -0500, Steven Rostedt wrote: > > Perhaps you could explain the use cases of your "flight recorder", > > because it seems that the name doesn't fit exactly, and this is > > causing me (and maybe others) some confusion. > 2) overwrite mode (flight recorder) - when the writer reaches the > reader, it pushes the reader forward, and writes the new events over the > old ones. This way, new events are always existent, where as old events > are lost. Ah, I forgot to mention use cases. Even when recording a trace (lots of data, so it is saved to disk and not all in kernel memory) I like to know that if something happens and disables the trace, I have all the trace information up to the point of failure. With producer/consumer mode, you risk the reader being late and the events in the trace that led up to failure (or any other anomaly) were dropped. -- Steve