Re: [ltt-dev] Tracing thread name

[Matthieu CASTET <matthieu.castet@parrot.com>]

Matthieu CASTET a écrit :
> Hi,
> 
> Mathieu Desnoyers a écrit :
>> * Matthieu CASTET (matthieu.castet@parrot.com) wrote:
>>> Hi Mathieu,
>>>
>>> Mathieu Desnoyers a écrit :
>>> Do you know if it is possible to patch my version to add such feature ?
>>>
>>> I saw that the name already change in the trace before/after an exec.
>>> How lltv get the new name ?
>>> With "fs.exec" tracepoint ?
>>> In that case I could fake a "fs.exec" tracepoint in set_task_comm.
>> A better solution : you add a new event in both lttng and lttv, and
>> modify state.c to support your new event. The current event to brand
>> thread is named "userspace.thread_brand". Look for this in LTTV to see
>> all the sites that need to support the new event (there are very few).
>>
> Thanks, but I want to avoid to modify too much ltt (I use an old version
> for 2.6.27 and my modifications may be useless for upstream).
> 
> I added "trace_fs_exec(tsk->comm);" at the end of set_task_comm and now
> the thread got the correct name :)
> 
BTW it is also interesting to get the name of the kernel threads
(created by kthread_create).
The current version of ltt show "kthreadd" for these threads.

The same solution than set_task_comm should solve the problem (comm is
set at the end of kthread_create).


Matthieu

PS: khelper thread are also annoying because they all got the same name.
May be it could be interesting to add extra info in the name.