[lttng-dev] lttng2.0, Babeltrace

[Stanislav Vovk]

Thanks for the quick reply.
Regarding tracepoint loglevels, you can ignore that issue, my misstake there. 

Interesting to hear that live view is not supported at the moment. So there is absolutely no way today to read traces "live"!? Looking forward to that feature to come, because it's of very big intrest to us. We were planning to start lttng at system boot and let it run and collect traces during the whole system up time and reading traces continuesly without stopping lttng. But for now we'll do as you adviced and wait for the "live view" feature.

/Stanislav


-----Original Message-----
From: Mathieu Desnoyers [mailto:mathieu.desnoyers at efficios.com] 
Sent: den 29 februari 2012 15:00
To: Stanislav Vovk
Cc: lttng-dev at lists.lttng.org; Julien Desfossez; Tan Dung Le Tran; Laverne Morrison
Subject: Re: [lttng-dev] lttng2.0, Babeltrace

Hi Stanislav,

* Stanislav Vovk (stanislav.vovk at ericsson.com) wrote:
> Hi
> 
> I have just started using and looking at LTTng2.0. It looks very user 
> friendly and easy to get started. Have a couple of questions thow.

I'm glad to hear that! :)

> 
> A question regarding Babeltrace, I have created a session and a 
> channel in flight recorder mode and started lttng. My application with 
> instrumented tracepoints is running and traces are successfully 
> recorded. When I stop my application I can read my traces with 
> babeltrace successfully. My concern is if I dont stop my application I 
> cant read traces with babeltrace, getting some CTF errors back. Can I 
> somehow read traces while my application is running? Is there 
> something I have missed, some option in babeltrace may be!

Babeltrace does not support "live" read at the moment, but you can do:

lttng stop
(which will stop tracing, and flush the buffers)

use babeltrace on the trace ("lttng view" is another way to invoke babeltrace on the current session)

live view of UST traces is an upcoming feature, which will be very likely in LTTng 2.1 or 2.2, which will appear somewhere in 2012.

> Regarding tracepoint loglevels, are all of them which are defined in 
> tracepoint.h implemented? Since I've tried to use some of them and gcc 
> complained it was not defined e.g. TRACE_DEBUG_FUNCTION. My git repo 
> is a couple of days old.

Yes, all the tracepoint loglevels implemented in tracepoint.h should work. The most up to date list, taken from git head, is:

enum {
        TRACE_EMERG             = 0,
        TRACE_ALERT             = 1,
        TRACE_CRIT              = 2,
        TRACE_ERR               = 3,
        TRACE_WARNING           = 4,
        TRACE_NOTICE            = 5,
        TRACE_INFO              = 6,
        TRACE_DEBUG_SYSTEM      = 7,
        TRACE_DEBUG_PROGRAM     = 8,
        TRACE_DEBUG_PROCESS     = 9,
        TRACE_DEBUG_MODULE      = 10,
        TRACE_DEBUG_UNIT        = 11,
        TRACE_DEBUG_FUNCTION    = 12,
        TRACE_DEBUG_LINE        = 13,
        TRACE_DEBUG             = 14,
};

So there is possibly an issue in the way you implemented your UST provider. I'm forwarding this to Tan, which I think would be your first point of contact at Ericsson for that kind of issue.

Thanks!

Mathieu

> 
> Thanks
> BR
> /Stanislav
> 
> 
> 
> STANISLAV VOVK
> Software developer
> 
> Ericsson AB
> RBS Platform
> Färögatan 6
> Stockholm, Sweden
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> stanislav.vovk at ericsson.com
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--
Mathieu Desnoyers
Operating System Efficiency R&D Consultant EfficiOS Inc.
http://www.efficios.com