Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933836AbZINVJh (ORCPT ); Mon, 14 Sep 2009 17:09:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933610AbZINVJh (ORCPT ); Mon, 14 Sep 2009 17:09:37 -0400 Received: from mail-ew0-f206.google.com ([209.85.219.206]:41999 "EHLO mail-ew0-f206.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933593AbZINVJg (ORCPT ); Mon, 14 Sep 2009 17:09:36 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=TCN5O1TOt5M94suV41ExsdQTiMl3n0Ib0DcQ1IcveKJLf4oxG+PWelEFIA+y+I/sWB OUlRsAzB+G6Cry3M139uot19M9nSml43P0OnKdqDqN2bOqLBR3Lb0z9rpDaWmfSrN3Mi qQ18DZBDQVA7X3nkmRJCePsTd01h+dvmmiNVI= Date: Mon, 14 Sep 2009 23:09:35 +0200 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: <20090914210933.GI6045@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> <20090914205250.GG6045@nowhere> <4AAEB149.2070300@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4AAEB149.2070300@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2250 Lines: 72 On Mon, Sep 14, 2009 at 05:10:33PM -0400, Masami Hiramatsu wrote: > Frederic Weisbecker wrote: >> 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. > > Hmm, I think it is better to treat the range as a type, because > we don't know how to express each entry without the type. > > NAME=ARG:TYPE[LEN] > e.g. > regs=sa:u64[16] > Yeah indeed, and that fits well in the NAME=ARG:TYPE logic that you have suggested. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/