[lttng-dev] tracing program flow

[Oestman, Fredrik]

Alexandre Montplaisir wrote:
> There's a feature on the wishlist to use GCC hooks to automatically
> generate those probes [1]. The end result would be the same, but it
> would be much less tedious to do the instrumentation part. A Clang
> plugin was also mentioned previously [2], but I don't think anybody has
> tried it yet.


Providing functions to GCC containing LTTng tracepoints isn't that much of a problem. We found it useful to add the thread ID to the trace data provided by GCC so we could keep the threads apart. As far as I know, this has to be made in application code at the moment, since LTTng can add context trace information only to kernel events at the moment.

We also have used the dynamic linker to add LTTng tracepoints to memory allocation and de-allocation functions as well as to the functions in the ptreads library. It can be done, but overhead is significant.

Any road-map information for the ability of LTTng to add context information to user-space events?


Cheers,

Fredrik Östman