Q1. (Calculation of communication cost) Given a 6*6 processor array which are numbered as
(i,j) (i, j = 1, 2, 3, 4, 5, 6) for a processor in row i and column j, arranged as a 2-dimensional
torus, and assuming cut-through routing, show the steps for One-to-all broadcast of 1,000 bytes
of data from processor (2, 2) to all the processors, and obtain an estimate for the time taken in
microseconds assuming the following parameters:
Startup time $t_s$ = 10 microseconds
Per hop time $t_h$ = 2 microseconds
Per byte time $t_w$ = 0.01 microseconds
Q2. (Calculation of communication cost) Continuing from Q1, please show the steps for an All-
to-all scatter of 6*6*1,000 bytes from each processor to every other processor (i.e. at
beginning, each processor has 6*6*1,000 bytes of data. At the end, each processor also has
6*6*1,000 bytes of data, but messages are scattered among 6*6 processors and totally
exchanged). Please obtain an estimate for the time taken in microseconds assuming the same
parameters as shown in Q1.