[ltt-dev] [UST RELEASE]ust 0.13

[Mathieu Desnoyers]

* Stefan Hajnoczi (stefanha at gmail.com) wrote:
> On Thu, May 19, 2011 at 2:22 PM, Mathieu Desnoyers
> <compudj at krystal.dyndns.org> wrote:
> > * Nils Carlson (nils.carlson at ericsson.com) wrote:
> >> Announcing the release of ust 0.13
> >>
> >> ChangeLog:
> >> 2011-05-19 ust 0.13
> >>         * API CHANGE!!! trace_mark has been deprecated, new ust_maker,
> >> without
> >>         channel name. ex. ust_marker(name, <format>, args...)
> >
> > Small note: for the deprecation process, we're leaving the old
> > "trace_mark" macros there for a few UST versions, but they will be
> > deprecated over time. We might enable compiler warnings in the next
> > release with the gcc "deprecated" attribute.
> >
> >>         * Instrumentation API CHANGE!!! change from
> >> trace_<name>(args...) to
> >>         tracepoint(name, args...), register_trace_<name>(...) to
> >>         register_tracepoint(name, ...) and unregister_trace_<name>(...) to
> >>         unregister_tracepoint(name, ...)
> >
> > As a side-note for this one: by the end of the summer, typical use the
> > UST instrumentation will be:
> >
> > TRACEPOINT_EVENT() for declaration
> > tracepoint(name, ...) in the code.
> 
> Has a point been reached where you are declaring the ust API stable?
> 
> For users it is a problem when the API changes, it should not be
> necessary to bundle a specific version of ust with an application.
> Right now using a distro ust-dev package for building applications
> against is not feasible due to API changes in across versions.
> 
> I think providing a stable API will increase adoption since
> distro-provided ust becomes useful and applications can begin to rely
> on tracing being there and working.

Hi Stefan,

We are in the process of getting there. I'm currently cleaning up the
exported APIs (it was a mess!) so we narrow down what is exported for
the whole world to see. In its current state, UST exposes the guts of
how it works, and that's definitely not good.

But given the TRACEPOINT_EVENT()/tracepoint() interface work is in
progress (and I want to make sure I get things right before I commit to
this API being stable), we plan to let people use the ust_marker() API.
It is less pretty and a bit harder to maintain in the application due to
lack of central instrumentation header per application, and traces a bit
more slowly due to dynamic traversal of the format string, but it works
today. Nils is planning to work on a conversion from ust_marker() to CTF
that will keep the current API in place over the summer.

If there is anything I can do to help out making the transition easier
for you, or something I should be aware of, please let me know!

Thanks,

Mathieu

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com