> To get real memory used, (Sys.word_size * live_word / 8). Do you use
> out-of-heap datastructure that can use memory ? (malloc-ed
> datastructure).

The only specific module is ocaml-fd (send file descriptors over pipes).
I have suspicion on it, but as I said before, 90% of process memory is
filled with specific text data, which is got inside threads and sent to
socket using Unix.write. This data doesn't look like file
descriptors :-)
All other modules are from distribution (Unix, String, Mutex, Threads).

I heard about ocaml-memprof patch. Will it help here?