From: Hemant <hkshaw@linux.vnet.ibm.com>
To: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>,
linux-kernel@vger.kernel.org, srikar@linux.vnet.ibm.com,
peterz@infradead.org, oleg@redhat.com, mingo@redhat.com,
anton@redhat.com, systemtap@sourceware.org
Subject: Re: [PATCH 1/2] SDT markers listing by perf
Date: Wed, 25 Sep 2013 06:04:00 -0000 [thread overview]
Message-ID: <52427CAE.8030600@linux.vnet.ibm.com> (raw)
In-Reply-To: <5242687A.9030209@hitachi.com>
On 09/25/2013 10:07 AM, Masami Hiramatsu wrote:
> (2013/09/15 20:28), Hemant wrote:
>> Hi Masami,
> Hi, and sorry for replying so late. I missed this in my mailbox.
>
>> On 09/04/2013 01:31 PM, Masami Hiramatsu wrote:
>>> (2013/09/04 15:42), Namhyung Kim wrote:
>>>> [SNIP]
>>>> You need to add it to Documentation/perf-probe.txt too. In addition if
>>>> the --sdt option is only able to work with libelf, it should be wrapped
>>>> into the #ifdef LIBELF_SUPPORT pair.
>>>>
>>>> And I'm not sure that it's a good idea to have two behavior on a single
>>>> option (S) - show and probe (add). Maybe it can be separated into two
>>>> or the S option can be used as a flag with existing --list and --add
>>>> option?
>>>>
>>> Good catch! :)
>>> No, that is really bad idea. All probes must be added by "--add" action.
>>> So we need a new probe syntax for specifying sdt marker.
>>>
>>> How about the below syntax?
>>>
>>> [EVENT=]%PROVIDER:MARKER [ARG ...]
>>>
>>> Of course, this will require to list up all markers with "%" prefix for
>>> continuity.
>>>
>>> And since --list option is to list up all existing(defined) probe events,
>>> I think --markers (as like as --funcs) is better for listing it up.
>>>
>>> Thank you!
>>>
>> I have one doubt here. Why do we need [ARG ...] in the syntax you
>> specified? I believe these args are to fetched from the sdt notes'
>> section of the elf of the executable/library. Or am I taking this in a
>> wrong way and this suggested syntax is actually for the uprobe_events
>> file in the tracing directory?
> Hm, indeed. Since all the arguments of the marker is defined in sdt notes,
> we actually don't need to specify each of them. However, other probe syntax
> has those arguments. I'd like to keep the same syntax style in the
> same command (action) for avoiding confusion.
Hmm, got it.
> I recommend this way; at the first step, we just find the marker address from
> sdt. And next, we will make the argument available. And eventually,
> it is better to introduce "$args" meta argument to fetch all the arguments
> of the marker.
>
> At this point, we can do
>
> perf probe %foo:bar $args
So, at first step (ignoring the arguments), we can go with :
perf probe %foo:bar
And, once, the argument support is enabled (all the arguments will be
fetched at the marker location), we can go with:
perf probe %foo:bar $args
>
> to trace full information from the marker foo:bar.
>
> Thank you,
>
--
Thanks
Hemant Kumar Shaw
next prev parent reply other threads:[~2013-09-25 6:04 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-03 7:36 [RFC PATCH 0/2] Perf support to SDT markers Hemant Kumar Shaw
2013-09-03 7:37 ` [PATCH 2/2] Support to perf to probe on SDT markers: Hemant Kumar
2013-09-03 9:14 ` Masami Hiramatsu
2013-09-04 7:00 ` Namhyung Kim
2013-09-04 8:10 ` Masami Hiramatsu
2013-09-04 18:00 ` Hemant
2013-09-04 17:50 ` Hemant
2013-09-03 7:37 ` [PATCH 1/2] SDT markers listing by perf Hemant Kumar
2013-09-03 8:19 ` Hemant
2013-09-04 6:43 ` Namhyung Kim
2013-09-04 17:40 ` Hemant
2013-09-04 6:42 ` Namhyung Kim
2013-09-04 8:02 ` Masami Hiramatsu
2013-09-04 17:59 ` Hemant
2013-09-15 11:28 ` Hemant
2013-09-25 4:37 ` Masami Hiramatsu
2013-09-25 6:04 ` Hemant [this message]
2013-09-25 8:45 ` Masami Hiramatsu
2013-09-04 17:38 ` Hemant
2013-09-06 6:38 ` Namhyung Kim
2013-09-06 8:41 ` Hemant
2013-09-04 7:22 ` Masami Hiramatsu
2013-09-04 17:52 ` Hemant
2013-09-03 8:25 ` [RFC PATCH 0/2] Perf support to SDT markers Ingo Molnar
2013-09-03 9:17 ` Masami Hiramatsu
2013-09-03 13:23 ` Hemant
2013-09-03 14:22 ` Ingo Molnar
2013-09-03 15:12 ` Mark Wielaard
2013-09-03 19:24 ` Ingo Molnar
2013-09-03 15:24 ` Hemant
2013-09-04 6:49 ` Namhyung Kim
2013-09-04 8:23 ` Masami Hiramatsu
2013-09-04 8:26 ` Mark Wielaard
2013-09-04 8:39 ` Masami Hiramatsu
2013-09-04 18:08 ` Hemant
2013-09-05 4:59 ` Masami Hiramatsu
2013-09-04 18:12 ` Hemant
2013-09-04 18:52 ` Mark Wielaard
2013-09-04 20:39 ` Hemant
2013-09-04 17:45 ` Hemant
2013-09-04 6:09 ` Namhyung Kim
2013-09-04 17:08 ` Hemant
2013-09-04 23:41 ` Andi Kleen
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