Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758732AbZGGV3h (ORCPT ); Tue, 7 Jul 2009 17:29:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758291AbZGGV3U (ORCPT ); Tue, 7 Jul 2009 17:29:20 -0400 Received: from mx2.redhat.com ([66.187.237.31]:58543 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758733AbZGGV3T (ORCPT ); Tue, 7 Jul 2009 17:29:19 -0400 Message-ID: <4A53BEAD.7030404@redhat.com> Date: Tue, 07 Jul 2009 17:31:25 -0400 From: Masami Hiramatsu User-Agent: Thunderbird 2.0.0.21 (X11/20090320) MIME-Version: 1.0 To: Frederic Weisbecker CC: Ingo Molnar , Steven Rostedt , lkml , systemtap , kvm , DLE , Ananth N Mavinakayanahalli , Christoph Hellwig , Tom Zanussi Subject: Re: [PATCH -tip -v10 7/7] tracing: add kprobe-based event tracer References: <20090701010838.32547.62843.stgit@localhost.localdomain> <20090701010923.32547.74203.stgit@localhost.localdomain> <20090707073103.GA6173@nowhere> <4A53A830.3000305@redhat.com> <20090707202008.GE6184@nowhere> <4A53B338.4060803@redhat.com> <20090707205851.GF6184@nowhere> In-Reply-To: <20090707205851.GF6184@nowhere> 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 Content-Length: 2921 Lines: 86 Frederic Weisbecker wrote: > On Tue, Jul 07, 2009 at 04:42:32PM -0400, Masami Hiramatsu wrote: >> Frederic Weisbecker wrote: >>> On Tue, Jul 07, 2009 at 03:55:28PM -0400, Masami Hiramatsu wrote: >>>> Frederic Weisbecker wrote: >>>>>> diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h >>>>>> index 206cb7d..65945eb 100644 >>>>>> --- a/kernel/trace/trace.h >>>>>> +++ b/kernel/trace/trace.h >>>>>> @@ -45,6 +45,8 @@ enum trace_type { >>>>>> TRACE_POWER, >>>>>> TRACE_BLK, >>>>>> TRACE_KSYM, >>>>>> + TRACE_KPROBE, >>>>>> + TRACE_KRETPROBE, >>>>>> >>>>>> __TRACE_LAST_TYPE, >>>>>> }; >>>>>> @@ -227,6 +229,22 @@ struct trace_ksym { >>>>>> char ksym_name[KSYM_NAME_LEN]; >>>>>> char p_name[TASK_COMM_LEN]; >>>>>> }; >>>>>> +#define TRACE_KPROBE_ARGS 6 >>>>>> + >>>>>> +struct kprobe_trace_entry { >>>>>> + struct trace_entry ent; >>>>>> + unsigned long ip; >>>>>> + int nargs; >>>>>> + unsigned long args[TRACE_KPROBE_ARGS]; >>>>> >>>>> I see that you actually make use of arg as a dynamic sizeable >>>>> array. >>>>> For clarity, args[TRACE_KPROBE_ARGS] could be args[0]. >>>>> >>>>> It's just a neat and wouldn't affect the code nor the data >>>>> but would be clearer for readers of that code. >>>> Hmm. In that case, I think we'll need a new macro for field >>>> definition, like TRACE_FIELD_ZERO(type, item). >>> >>> >>> You mean that for trace_define_field() to describe fields of events? >>> Actually the fields should be defined dynamically depending on how >>> is built the kprobe event (which arguments are requested, how many, >>> etc..). >> Yeah, if you specified a probe point with its event name, the tracer >> will make a corresponding event dynamically. There are also anonymous >> probes which don't have corresponding events. For those anonymous >> probes, I need to define two generic event types(kprobe and kretprobe). >> >> Thank you, > > > Ok. Btw, why do you need to define those two anonymous events? > Actually your event types are always dynamically created. > Those you defined through TRACE_FORMAT_EVENT are only "ghost events", > they only stand there as a abstract pattern, right? > Not always created. Below command will create an event "event1"; p probe_point:event1 a1 a2 a3 ... > /debug/tracing/kprobe_events But next command doesn't create. p probe_point a1 a2 a3 ... > /debug/tracing/kprobe_events This just inserts a kprobe to probe_point. the advantage of this "simple" command is that you never be annoyed by making different name for new events :-) Thank you, -- Masami Hiramatsu Software Engineer Hitachi Computer Products (America), Inc. Software Solutions Division e-mail: mhiramat@redhat.com -- 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/