Q.1 Provide formulae for computing the number of read stall cycles and write stall cycles for a given program executing on a given machine.
Q.2 Explain briefly why read stalls and write stalls occur.
Q.3 A machine takes on average c cycles per instruction without considering memory stalls, and has a miss penalty p for all misses. Let i and d be respectively the instruction cache miss rate and data cache miss rate for a program with n instructions and f memory references per instruction. Assume that the hit time is not a factor in determining cache performance.
(i) How many cycles are required to run this program, when memory stall is taken into account?
(ii) If we want to improve the execution time of this program by a factor of k, how much do we need to reduce the number of cycles that each instruction takes?
(iii) Another way to improve the execution time is to reduce the cycle time of the machine. If we want to improve the execution time by a factor of k, how much do we need to improve the cycle time?