Message Startup Latencies

Table 4.2: Time for 1 Byte Messages

	Wsock	WMPI-C	WMPI-J	MPICH-C	MPICH-J
SM	144.8 $\mu$s	67.2 $\mu$s	161.4 $\mu$s	148.7 $\mu$s	374.6 $\mu$s
DM	244.9 $\mu$s	623.9 $\mu$s	689.7 $\mu$s	679.1 $\mu$s	961.2 $\mu$s

In Table 4.2 we show the transmission time in microseconds ($\mu$s) to send a 1 byte message in each of the environments tested. In shared memory mode (SM) the mpiJava wrapper adds an extra 94$\mu$s (140%) and 226$\mu$s (152%) compared to WMPI and MPICH C respectively. In distributed memory mode (DM) the mpiJava wrapper adds an extra 66$\mu$s (11%) and 282$\mu$s (42%) compared to WMPI and MPICH C respectively. The ``Wsock'' figures are those for a WinSock implementation of PingPong benchmark using TCP.