From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752697AbYIXV3Y (ORCPT ); Wed, 24 Sep 2008 17:29:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751751AbYIXV3P (ORCPT ); Wed, 24 Sep 2008 17:29:15 -0400 Received: from mx1.redhat.com ([66.187.233.31]:55458 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751686AbYIXV3P (ORCPT ); Wed, 24 Sep 2008 17:29:15 -0400 Date: Wed, 24 Sep 2008 17:24:33 -0400 From: "Frank Ch. Eigler" To: Martin Bligh Cc: David Miller , torvalds@linux-foundation.org, rostedt@goodmis.org, peterz@infradead.org, linux-kernel@vger.kernel.org, mingo@elte.hu, tglx@linutronix.de, akpm@linux-foundation.org, prasad@linux.vnet.ibm.com, compudj@krystal.dyndns.org, dwilder@us.ibm.com, hch@lst.de, zanussi@comcast.net, srostedt@redhat.com Subject: Re: [RFC PATCH 1/3] Unified trace buffer Message-ID: <20080924212433.GB14763@redhat.com> References: <20080924.133720.72895701.davem@davemloft.net> <33307c790809241351k53f322a1o794dd73255393e11@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <33307c790809241351k53f322a1o794dd73255393e11@mail.gmail.com> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi - On Wed, Sep 24, 2008 at 01:51:55PM -0700, Martin Bligh wrote: > [...] > One thing we said we could do is compile the "decompaction" tools > along with the kernel, in the kernel tree. Then if we change the in-kernel > format, you don't break all the userspace tools. If the common tracing idea still includes kernel-supplied ASCII as an alternative to binary (so that one could grep some debugfs file), then it would be nice to have some common code for decoding the trace records offline. If we can associate a simple specific struct type ("struct ftrace_event") with each trace id type in an object-code-resident table, we could automate some of this. The kernel build process could sniff dwarf data (a la acme's struct-layout-printing dwarves) at or before modpost time to generate a snippet of C code for each such event struct. That C code could be the generic ASCII-printing callback for use by debugfs. A variant could be a userspace-usable version. Given the same id-to-struct-name mapping, Sytemtap could expose event records field by field, by name. - FChE