[lttng-dev] How to disable an event that's been enabled by a wildcard selection or -a?

[Woegerer, Paul]

Hi David,

On 02/14/2013 05:52 AM, David OShea wrote:
> Hi,
> 
> My understanding (hopefully someone will correct me if I'm wrong) is that each time you invoke 'lttng enable-event', your specification for the events you want enabled is stored and applied, and/or potentially applied later if a new application connects to the session daemon.  All 'lttng disable-event' does is remove one of the specifications you previously provided to 'lttng enable-event', so you can't say 'enable-event *' and then 'disable-event foo:*' to get all events except 'foo:*'.
> 
> If you could constrain the application to use a particular trace provider name for all of its tracepoints, say "app", then you could just do 'lttng enable-event app:*'.  If you can't do that, then I think you need to fall back on getting a list of all the available tracepoints using 'lttng list -u', parsing this to find all of the available tracepoints, extracting the trace provider name from them, then using 'lttng enable-event <provider>:*' for each provider other than the provider from your uninteresting library.  I think there are APIs that can be used instead of issuing the 'lttng' commands.
> 
> I would certainly also like a way to be able to, say, enable all events other than foo:* and bar:* using one command.

I submitted a patch that does exactly this a while ago:
http://lists.lttng.org/pipermail/lttng-dev/2012-June/018179.html

Although it's not upstream it works well for us.

Thanks,
Paul


> 
> Regards,
> David
> 
>> -----Original Message-----
>> From: Ikaheimonen, JP [mailto:jp_ikaheimonen at mentor.com]
>> Sent: Friday, 8 February 2013 7:56 PM
>> To: lttng-dev at lists.lttng.org
>> Subject: [lttng-dev] How to disable an event that's been enabled by a
>> wildcard selection or -a?
>>
>> Consider the following scenario.
>> I want to write a script that traces all UST tracepoints of a given
>> application. I have no idea what the names of these tracepoints are.
>> Also, I know that the application uses a library that contains some
>> tracepoints I am not interested about. Now I want to trace all UST
>> tracepoints except the ones I already know about. Is this possible with
>> the lttng commands?
>>
>> If I enable all tracepoints with "lttng enable-event -u -a" I get all
>> events, even those I do not want. I've tried using "lttng disable-
>> event", and "lttng enable-event" with a filter, but I cannot seem to be
>> able to get rid of the specific events.
>>
>> Thank you,
>>
>> JP Ikaheimonen
>> Mentor Graphics Embedded Systems Division
>> Nucleus(r) | Linux(r) | Android(tm) | Services | UI | Multi-OS
>>
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-- 
Paul Woegerer | SW Development Engineer
http://go.mentor.com/sourceryanalyzer

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Android is a trademark of Google Inc. Use of this trademark is subject
to Google Permissions.
Linux is the registered trademark of Linus Torvalds in the U.S. and
other countries.