Thanks Guys, that was the issue, I appreciate your help

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Today's Topics:

   1. User Space Tracing (John O'Sullivan)
   2. Re: User Space Tracing (Philippe Proulx)
   3. Re: User Space Tracing (Mathieu Desnoyers)


----------------------------------------------------------------------

Message: 1
Date: Thu, 27 Sep 2018 16:13:37 +0000
From: John O'Sullivan <john.osulli...@blackbox.com>
To: "lttng-dev@lists.lttng.org" <lttng-dev@lists.lttng.org>
Subject: [lttng-dev] User Space Tracing
Message-ID: <1538064817178.44...@blackbox.com>
Content-Type: text/plain; charset="iso-8859-1"

I am really struggling trying to get user space tracing working predictably and 
consistently and would appreciate some help.


I created a trace event called

kvm_server:new_connection_tracepoint (see attached), I then use lttng-gen-tp to 
generate the .c and .h files which I link to the program and call with

tracepoint(kvm_server, new_connection_tracepoint, .................)

This appears predictably in my traces

However if I call my second tracepoint (see attached)

tracepoint(resolution_management, resolution_management_tracepoint,.......)

It never appears in any of the traces

I can see no significant difference between the two definitions.


I then created a third trace definition called simple_example (see attached)

tracepoint(simple_example, simple_example_tracepoint, .....)

This again appears in the trace


I start the tracing using

lttng enable-event -u -a      # enable user-space tracing

I then use babel trace to dump the trace,


'kvm_server' and 'simple_example' appear in the trace,  resolution_management 
does not.



Any idea why the resolution_management tracepoint does not appear in any traces 
or is there some way of debugging the tracecall macro itself?


regards

John

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------------------------------

Message: 2
Date: Thu, 27 Sep 2018 13:51:05 -0400
From: Philippe Proulx <eeppelitel...@gmail.com>
To: john.osulli...@blackbox.com
Cc: lttng-dev@lists.lttng.org
Subject: Re: [lttng-dev] User Space Tracing
Message-ID:
        <cab4xu_1zofu02ia_xxp0lzu2u+r_rqltq-eadxol1z66kbb...@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"

In `resolution_management_tp.tp`, can you try using the exact same
`TP_ARGS` content for both `TRACEPOINT_EVENT_INSTANCE` (also matching
the `TP_ARGS` content of `TRACEPOINT_EVENT_CLASS`)? It's the only
difference I can see.

Philippe Proulx
Philippe Proulx


On Thu, Sep 27, 2018 at 12:15 PM John O'Sullivan
<john.osulli...@blackbox.com> wrote:
>
> I am really struggling trying to get user space tracing working predictably 
> and consistently and would appreciate some help.
>
>
> I created a trace event called
>
> kvm_server:new_connection_tracepoint (see attached), I then use lttng-gen-tp 
> to generate the .c and .h files which I link to the program and call with
>
> tracepoint(kvm_server, new_connection_tracepoint, .................)
>
> This appears predictably in my traces
>
> However if I call my second tracepoint (see attached)
>
> tracepoint(resolution_management, resolution_management_tracepoint,.......)
>
> It never appears in any of the traces
>
> I can see no significant difference between the two definitions.
>
>
> I then created a third trace definition called simple_example (see attached)
>
> tracepoint(simple_example, simple_example_tracepoint, .....)
>
> This again appears in the trace
>
>
> I start the tracing using
>
> lttng enable-event -u -a      # enable user-space tracing
>
> I then use babel trace to dump the trace,
>
>
> 'kvm_server' and 'simple_example' appear in the trace,  resolution_management 
> does not.
>
>
>
> Any idea why the resolution_management tracepoint does not appear in any 
> traces or is there some way of debugging the tracecall macro itself?
>
>
> regards
>
> John
>
>
> ________________________________
>
> This email and any files transmitted with it are confidential and are 
> intended for the sole use of the individual to whom they are addressed. Black 
> Box Corporation reserves the right to scan all e-mail traffic for restricted 
> content and to monitor all e-mail in general. If you are not the intended 
> recipient or you have received this email in error, any use, dissemination or 
> forwarding of this email is strictly prohibited. If you have received this 
> email in error, please notify the sender by replying to this email.
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------------------------------

Message: 3
Date: Thu, 27 Sep 2018 15:32:48 -0400 (EDT)
From: Mathieu Desnoyers <mathieu.desnoy...@efficios.com>
To: Philippe Proulx <eeppelitel...@gmail.com>
Cc: John OSullivan <john.osulli...@blackbox.com>,  lttng-dev
        <lttng-dev@lists.lttng.org>
Subject: Re: [lttng-dev] User Space Tracing
Message-ID:
        <1491039245.11707.1538076768518.javamail.zim...@efficios.com>
Content-Type: text/plain; charset=utf-8

Good catch Philippe,

I pushed a commit that enforces validation of event class/instance
prototypes (TP_ARGS()) at compile-time.

It is pushed into lttng-ust master as:

commit c75c0422c64f33c0102e1778cecc812c58b700e5
Author: Mathieu Desnoyers <mathieu.desnoy...@efficios.com>
Date:   Thu Sep 27 15:21:16 2018 -0400

    Fix: check for event class/instance prototype mismatch
    
    The TP_ARGS() for an event instance belonging to an event class
    must have compatible types with the event class TP_ARGS().
    
    Failure to follow this rule leads to a prototype mismatch between the
    tracepoint call site and the probe function. A common effect perceived
    is that events with prototype mismatch between call site and probe
    function are never traced.
    
    Fix this by enforcing a compile-time check of the event instance and
    class prototypes, similarly to what is done in LTTng modules.
    
    Signed-off-by: Mathieu Desnoyers <mathieu.desnoy...@efficios.com>

And cherry-picked into lttng-ust 2.11, 2.10, 2.9 stable branches,

Thanks!

Mathieu

----- On Sep 27, 2018, at 1:51 PM, Philippe Proulx eeppelitel...@gmail.com 
wrote:

> In `resolution_management_tp.tp`, can you try using the exact same
> `TP_ARGS` content for both `TRACEPOINT_EVENT_INSTANCE` (also matching
> the `TP_ARGS` content of `TRACEPOINT_EVENT_CLASS`)? It's the only
> difference I can see.
> 
> Philippe Proulx
> Philippe Proulx
> 
> 
> On Thu, Sep 27, 2018 at 12:15 PM John O'Sullivan
> <john.osulli...@blackbox.com> wrote:
>>
>> I am really struggling trying to get user space tracing working predictably 
>> and
>> consistently and would appreciate some help.
>>
>>
>> I created a trace event called
>>
>> kvm_server:new_connection_tracepoint (see attached), I then use lttng-gen-tp 
>> to
>> generate the .c and .h files which I link to the program and call with
>>
>> tracepoint(kvm_server, new_connection_tracepoint, .................)
>>
>> This appears predictably in my traces
>>
>> However if I call my second tracepoint (see attached)
>>
>> tracepoint(resolution_management, resolution_management_tracepoint,.......)
>>
>> It never appears in any of the traces
>>
>> I can see no significant difference between the two definitions.
>>
>>
>> I then created a third trace definition called simple_example (see attached)
>>
>> tracepoint(simple_example, simple_example_tracepoint, .....)
>>
>> This again appears in the trace
>>
>>
>> I start the tracing using
>>
>> lttng enable-event -u -a      # enable user-space tracing
>>
>> I then use babel trace to dump the trace,
>>
>>
>> 'kvm_server' and 'simple_example' appear in the trace,  resolution_management
>> does not.
>>
>>
>>
>> Any idea why the resolution_management tracepoint does not appear in any 
>> traces
>> or is there some way of debugging the tracecall macro itself?
>>
>>
>> regards
>>
>> John
>>
>>
>> ________________________________
>>
>> This email and any files transmitted with it are confidential and are 
>> intended
>> for the sole use of the individual to whom they are addressed. Black Box
>> Corporation reserves the right to scan all e-mail traffic for restricted
>> content and to monitor all e-mail in general. If you are not the intended
>> recipient or you have received this email in error, any use, dissemination or
>> forwarding of this email is strictly prohibited. If you have received this
>> email in error, please notify the sender by replying to this email.
>> _______________________________________________
>> lttng-dev mailing list
>> lttng-dev@lists.lttng.org
>> https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
> _______________________________________________
> lttng-dev mailing list
> lttng-dev@lists.lttng.org
> https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com


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