Hello Hong,
the initial amount 'em/initial_size_MB' of extended memory will be allocated first, and it will be extended if needed until EM/TOTAL_SIZE_MB is reached. What is the value for EM/TOTAL_SIZE_MB in the affected system? It will not make much sense to increase only em/initial_size_MB, the maximum amount of extended memory is restricted by EM/TOTAL_SIZE_MB.
Reg. RAM - an estimation is
RAM+swap = heap + extended memory
regards,
Alwina