From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754705AbYIYSQh (ORCPT ); Thu, 25 Sep 2008 14:16:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752842AbYIYSQ2 (ORCPT ); Thu, 25 Sep 2008 14:16:28 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:39041 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750733AbYIYSQ1 (ORCPT ); Thu, 25 Sep 2008 14:16:27 -0400 Date: Thu, 25 Sep 2008 11:14:57 -0700 (PDT) From: Linus Torvalds To: Steven Rostedt cc: Peter Zijlstra , Martin Bligh , Martin Bligh , linux-kernel@vger.kernel.org, Ingo Molnar , Thomas Gleixner , Andrew Morton , prasad@linux.vnet.ibm.com, Mathieu Desnoyers , "Frank Ch. Eigler" , David Wilder , hch@lst.de, Tom Zanussi , Steven Rostedt Subject: Re: [RFC PATCH 1/3] Unified trace buffer In-Reply-To: Message-ID: References: <20080924051056.650388887@goodmis.org> <33307c790809240847r31c8b683na15ff5488b60d25b@mail.gmail.com> <1222272686.16700.162.camel@lappy.programming.kicks-ass.net> <33307c790809240949i3026170i8f9ac1d67a0fcf00@mail.gmail.com> <33307c790809241403w236f2242y18ba44982d962287@mail.gmail.com> <1222339303.16700.197.camel@lappy.programming.kicks-ass.net> <8f3aa8d60809250733q70561e6agfa3b00da83773e9f@mail.gmail.com> <1222354409.16700.215.camel@lappy.programming.kicks-ass.net> User-Agent: Alpine 1.10 (LFD 962 2008-03-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 25 Sep 2008, Steven Rostedt wrote: > > The one thing that seemed to me most apparent from talking to people > at LPC, is that they want a simple ring buffer API. If every tracer that > uses this must come up with its own time keeping management, I don't think > this will be used at all (except by those that are maintaining tracers > now). No, no. The timestamp code is all in the ring buffer code. That was why I refused to have the layering without it. And hell no, nobody should *ever* read the "tsc_delta" fields etc. Those are entirely internal to the buffering. If any user _ever_ reads or writes those on its own, it's a bug, plain and simple. So when you read trace events, you should get the event data and the timestamp from the trace buffer routines. Nobody should ever even _see_ the internal trace buffer implementation! Linus