Alternative to -pg for clang?

Clang Frontend
1

I observed there is no implementation of -pg for clang. Is there any
plan to do this, or an alternative framework in place? Can anyone
recommend an alternative free and effective sampling profiler with
minimal overhead?

2

Don't know about a plan for -pg, but since I've been evaluating Linux
profiling tools for a class recently, I'll give some recommendations.

If you're using Linux, I'd recommend "perf" (aka "Linux Perf Events"
or "Linux Performance Counters", names that are un-google-able). The
command line interface is *much* easier to use than oprofile for
performance counters, which is what I was interested in. I think the
callgraph support is a bit weaker than gprof. It handled recursion
*very* poorly, which is pretty lame. The main things to like about it
are the interface, low overhead, and the fact that you don't need to
rebuild.

There's also google-perftools cpuprofiler:
http://google-perftools.googlecode.com/svn/trunk/doc/cpuprofile.html
I've only used their heap profiler, which worked reasonably well.
Google uses this for everything apparently, so it's probably not half
bad.

Reid

3

Thanks for the pointers, I was hoping very much for something other
than the usual recommendations of "Zoom" and "OProfile". I'll give
these profilers you've suggested a try.

4

If you can stand the performance penalty, cachegrind + kcachegrind are
also available and can produce some very detailed information.

- Daniel