Using valgrind with opencog can be tricky, because many spurious messages are created. These can be suppressed with suppression files, like so:
valgrind --suppressions=../lib/valgrind.guile.suppressions \
--suppressions=../lib/valgrind.python.suppressions \
--suppressions=../lib/valgrind.boost.suppressions \
--suppressions=../lib/valgrind.logger.suppressions \
--suppressions=../lib/valgrind.link-grammar.suppressions \
<program_to_debug>
where <program_to_debug> is probably opencog/server/cogserver
Memory leaks: valgrind --leak-check=full
Memory non-leaks: valgrind --leak-check=full --show-leak-kinds=all
Memory profile: valgrind --tool=massif
CPU profile: valgrind --tool=callgrind
then: callgrind_annotate callgrind.out.nnnn