[lttng-dev] [RFC PATCH 0/2] Identify UST threads by changing thread names

[Jérémie Galarneau]

Hi Raphaël,

Adding Mathieu in CC. Please make sure you CC the maintainers when
submitting a patch.

Regards,
Jérémie

On Wed, Jun 1, 2016 at 11:04 AM, Raphaël Beamonte
<raphael.beamonte at gmail.com> wrote:
> Hi,
>
> I did not get any feedback about this, any thoughts ?
>
> Thanks,
> Raphaël
>
> 2016-04-21 16:50 GMT-04:00 Raphaël Beamonte <raphael.beamonte at gmail.com>:
>> Hi,
>>
>> This is an RFC patch for comments and ideas about how this should be
>> done. In recent work I've been doing, I found out that some UST-
>> instrumented userspace process was preempting itself. Looking further,
>> it was not the same TID, but the same process name. These processes
>> were LTTng-UST listener threads, but were not identified as so.
>> Adding a simple symbol, such as "-ust" or "-lttng" at the end of the
>> process name would help to identify such process directly in the
>> generated trace.
>>
>> You'll find below two different implementations with their pros
>> and cons, for which the "-ust" symbol was choosen:
>>
>>
>> 1/ An implementation using prctl
>>         It works properly on Linux, but I didn't find a way to make
>>         it work under FreeBSD, hence the empty function in FreeBSD
>>         case (keeping the situation as it is now).
>>
>> Raphaël Beamonte (1):
>>   Add -ust to the name of UST threads of the application
>>
>>  liblttng-ust/compat.h         | 22 ++++++++++++++++++++++
>>  liblttng-ust/lttng-ust-comm.c |  2 ++
>>  2 files changed, 24 insertions(+)
>>
>>
>>
>> 2/ An implementation using pthread
>>         It works on both Linux and FreeBSD, but requires to add a
>>         link to the pthread library in liblttng-ust Makefile.am.
>>         Also, this approach relies on the presence of the
>>         pthread_setname_np function, which was included in glibc
>>         2.12, meaning it will not work with older versions (but
>>         this should not be a problem?)
>>
>> Raphaël Beamonte (1):
>>   Add -ust to the name of UST threads of the application
>>
>>  liblttng-ust/Makefile.am      |  1 +
>>  liblttng-ust/compat.h         | 35 +++++++++++++++++++++++++++++++++++
>>  liblttng-ust/lttng-ust-comm.c |  2 ++
>>  3 files changed, 38 insertions(+)
>>
>>
>>
>> I'll wait for your comments and ideas on that subject.
>>
>> Thanks,
>> Raphaël
>>
>>
>> --
>> 2.1.4
>>
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-- 
Jérémie Galarneau
EfficiOS Inc.
http://www.efficios.com