From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754316AbYIWAHI (ORCPT ); Mon, 22 Sep 2008 20:07:08 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751330AbYIWAG5 (ORCPT ); Mon, 22 Sep 2008 20:06:57 -0400 Received: from mx1.redhat.com ([66.187.233.31]:59981 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751248AbYIWAG5 (ORCPT ); Mon, 22 Sep 2008 20:06:57 -0400 Message-ID: <48D83295.7020301@redhat.com> Date: Mon, 22 Sep 2008 20:04:37 -0400 From: Masami Hiramatsu User-Agent: Thunderbird 2.0.0.16 (X11/20080723) MIME-Version: 1.0 To: Darren Hart CC: Martin Bligh , Linux Kernel Mailing List , Linus Torvalds , Thomas Gleixner , Mathieu Desnoyers , Steven Rostedt , od@novell.com, "Frank Ch. Eigler" , systemtap-ml Subject: Re: Unified tracing buffer References: <33307c790809191433w246c0283l55a57c196664ce77@mail.gmail.com> <48D7F5E8.3000705@redhat.com> <33307c790809221313s3532d851g7239c212bc72fe71@mail.gmail.com> <48D81B5F.2030702@redhat.com> In-Reply-To: X-Enigmail-Version: 0.95.7 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Darren, Darren Hart wrote: > On Mon, Sep 22, 2008 at 3:25 PM, Masami Hiramatsu wrote: > >>> One thing that I think is still important is to have a unified timestamp >>> mechanism on everything, so we can co-ordinate different things back >>> together in userspace from different trace tools, so I intend to keep >>> that at a lower level, but I think you're right that the event id, etc can >>> move up into separate layers. >> I'm not so sure that the unified 'timestamp' must be required by all tracers. >> If you just need to merge and sort per-cpu data, you can use an atomic >> sequential number for it. >> IMHO, the unified 'timestamp' would better be an option, because some >> architectures can't support it. I think preparing timestamp-callback >> function will help us. >> > > There have been several posts on the timestamp for the events. From a > real-time perspective, this timestamp will be a very important datapoint for > each event, and the more accurate/higher resolution the better. Some thoughts. Sure, I know the precise timestamp is required for real-time sensitive tracers. however, there are some other cases. for example debugging, we don't need timestamps, but just want to know the order of events. :-) Thank you, -- Masami Hiramatsu Software Engineer Hitachi Computer Products (America) Inc. Software Solutions Division e-mail: mhiramat@redhat.com