Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758951AbZGGVkc (ORCPT ); Tue, 7 Jul 2009 17:40:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756992AbZGGVkY (ORCPT ); Tue, 7 Jul 2009 17:40:24 -0400 Received: from mx2.redhat.com ([66.187.237.31]:48221 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756254AbZGGVkX (ORCPT ); Tue, 7 Jul 2009 17:40:23 -0400 Message-ID: <4A53C144.20807@redhat.com> Date: Tue, 07 Jul 2009 17:42:28 -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> <4A53BEAD.7030404@redhat.com> <20090707213447.GC7412@nowhere> In-Reply-To: <20090707213447.GC7412@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: 3478 Lines: 98 Frederic Weisbecker wrote: > On Tue, Jul 07, 2009 at 05:31:25PM -0400, Masami Hiramatsu wrote: >> 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 > > > Aah, ok. > > >> 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 :-) > > > Indeed. > But speaking about that, may be you could dynamically create a name > following this simple model: func+offset > Unless we can set several kprobes on the exact same address? Actually, we can... I thought that someone might want to insert events in the same address for retrieving more than 6 arguments. Thanks, -- 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/