> Can anyone tell me approximately what fraction of time is
> spent in garbage collection, or even better, combined allocation and
> collection, in typical caml programs?

It depends how allocation-intensive your program is.  For instance, the
Knuth-Bendix benchmark (which allocates quite a lot of short-lived
data) spends about 20% of its time in GC and allocation in the major
heap, when compiled with ocamlopt on a Pentium.

The percentage is lower for bytecode programs, because the collector
still runs at the same speed while the mutator runs more slowly
because of the interpretation overhead.

Most allocations in the minor heap are expanded in-line, so they can't
be measured.

Hope this helps,

- Xavier Leroy