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

[Raphaël Beamonte]

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
>