To complement the above communication benchmarks, there is a need for
a benchmark to measure the total saturation bandwidth of the complete
communication system, and to see how this scales with the number
of processors. A natural generalisation of the COMMS2 benchmark
is made as follows, and called the COMMS3 benchmark:
Each processor of a **p**-processor system sends a message of length **n**
to the other (p-1) processors. Each processor then waits to receive
the (p-1) messages directed at it. The timing of this generalised
* pingpong* ends when all messages have been successfully received by all
processors; although the process will be repeated many times to obtain
an accurate measurement, and the overall time will be divided by the
number of repeats. The time for the generalised pingpong is the time to
send p(p-1) messages of length **n** and can be analysed in the same way
as COMMS1 and COMMS2 into values of (\rnhalf). The value obtained for \rinf is the required total saturation bandwidth, and we are interested in how
this scales up as the number of processors **p** increases and with it the
number of available links in the system.

COMMS3 is a new benchmark written specifically for PARKBENCH .

Tue Nov 14 15:43:14 PST 1995