From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 32509 invoked by alias); 14 Sep 2009 20:53:02 -0000 Received: (qmail 32500 invoked by uid 22791); 14 Sep 2009 20:53:02 -0000 X-SWARE-Spam-Status: No, hits=-2.4 required=5.0 tests=AWL,BAYES_00,SPF_PASS X-Spam-Check-By: sourceware.org Received: from ey-out-1920.google.com (HELO ey-out-1920.google.com) (74.125.78.146) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Mon, 14 Sep 2009 20:52:57 +0000 Received: by ey-out-1920.google.com with SMTP id 5so696133eyb.24 for ; Mon, 14 Sep 2009 13:52:55 -0700 (PDT) Received: by 10.210.3.21 with SMTP id 21mr3674570ebc.15.1252961575352; Mon, 14 Sep 2009 13:52:55 -0700 (PDT) Received: from nowhere (ADijon-552-1-91-97.w92-148.abo.wanadoo.fr [92.148.138.97]) by mx.google.com with ESMTPS id 7sm2411825eyb.5.2009.09.14.13.52.52 (version=SSLv3 cipher=RC4-MD5); Mon, 14 Sep 2009 13:52:54 -0700 (PDT) Received: by nowhere (nbSMTP-1.00) for uid 1000 (using TLSv1/SSLv3 with cipher RC4-MD5 (128/128 bits)) fweisbec@gmail.com; Mon, 14 Sep 2009 22:52:54 +0200 (CEST) Date: Mon, 14 Sep 2009 20:53:00 -0000 From: Frederic Weisbecker To: Masami Hiramatsu Cc: Steven Rostedt , Ingo Molnar , lkml , Ananth N Mavinakayanahalli , Andi Kleen , Christoph Hellwig , "Frank Ch. Eigler" , "H. Peter Anvin" , Jason Baron , Jim Keniston , "K.Prasad" , Lai Jiangshan , Li Zefan , Peter Zijlstra , Srikar Dronamraju , Tom Zanussi , systemtap , DLE Subject: Re: [PATCH tracing/kprobes 0/7] tracing/kprobes: kprobe-based event tracer update and perf support Message-ID: <20090914205250.GG6045@nowhere> References: <20090910235258.22412.29317.stgit@dhcp-100-2-132.bos.redhat.com> <20090911013332.GB16396@nowhere> <4AAA74D2.9060203@redhat.com> <20090914025949.GB14306@nowhere> <4AAE7A5D.8010503@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4AAE7A5D.8010503@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org X-SW-Source: 2009-q3/txt/msg00714.txt.bz2 On Mon, Sep 14, 2009 at 01:16:13PM -0400, Masami Hiramatsu wrote: > Frederic Weisbecker wrote: >> On Fri, Sep 11, 2009 at 12:03:30PM -0400, Masami Hiramatsu wrote: >>> Frederic Weisbecker wrote: >>>> May be another step in the todo-list that would be nice: define the format >>>> for a type. Like it's done from ftrace events. >>> >>> Thanks! >>> >>> BTW, I'm not sure what the type means. Each event already has its own >>> event ID and event_call. Could you tell me which part of ftrace I should >>> refer to ? >>> >> >> >> Actually I meant the format for a field. >> Say you define filename=arg1, it would be nice to have >> >> print "%s", filename >> >> in the format file. > > Ah, indeed. It is better to support 'type' casting for each argument. > I think type casting can be done as below syntax. > > NAME=ARG:TYPE > e.g. > jiffies64=@jiffies64:u64 > message=%ax:str > Yeah looks good! >> Hmm, now that I think about it, we can't dereference an array...for now :-) > > :-) > BTW, currently, an entry of the array can be shown, e.g. +10(sa). > Hmm, for more complex dereference(e.g. accessing a->b[a->c]), it might need > another dereferencing syntax(e.g. "sa[16][sa[8]]"), or > just allow to use braces(e.g. "+(+8(sa))(+16(sa))"). Well, that may be too much complexity. I guess if we want multi level dereference, say you want a->b->c it should be sufficient to probe the point where b->c gets it's value (if any). But it would be nice to fetch a range: sa[begin:end] Or at least just giving the length of the range.