Profiling tools?

[Matt Welsh]

Hi all,

Does anyone have any experience with using profiling tools (e.g., gprof)
with gcj-compiled Java programs?

I am trying to find out why a certain complex, multithreaded, sockets-based
program of ours seems to run slower using gcj than with other JVM+JIT 
combinations. Running individual microbenchmarks doesn't seem to explain
what's going on; ideally I'd like to use "gcj -pg" and run gprof to find
out where the time is going. This works, but gprof always reports that the 
application consumed zero time, which is obviously untrue.

My guess is that gprof is simply unsupported under gcj, but it might be
sufficient to profile the non-Java parts of this program. How hard would 
it be to build libgcj using -pg, so I can get a profiling trace of the 
runtime itself? What is the simplest way to pass that option along to 
the Makefiles?

Thanks much!
Matt Welsh