Exercise 4. [30 Marks The following tables summarizes the instructions present in some program (Table 1) as well as two different processors (Table 2). Operation ALU Load Store Branch Instruction Count 2000 1000 600 400 Operation ALU Load Store Branch Processor 1 Processor 2 3 1 4 6 3 3 2 2 Table 1: Program Instructions Table 2: Processor Instruction Cycles (a) [5 Marks] Calculate the ideal CPI of this program running on Processor 1. (b) [5 Marks] Calculate the ideal CPI of this program running on Processor 2. (c) (5 Marks) Assuming that Processor 1 operates at 2.8 GHz and Processor 2 operates at 2.4 GHz calculate the CPU time for the program when run on each processor. On which processor is the program faster? (Hint: for easy calculations, 1GHz = 1 x 10Hz) (d) [5 Marks] In terms of the three factors calculating CPU time (instruction count, CPI, clock frequency) explain why the processor from part (c) is the faster one. How could a programmer change the program described in Table 1 so that it would run faster on the other processor? (e) [10 Marks Calculate the CPU time of the program described in Table 1 running on Processor 1 (at 2.8 GHz) when also considering memory stall cycles (and thus have CPU time calculated using CPIstall). Assume this processor has one level of cache, an instruction miss rate of 2%, a data miss rate of 5% and a miss penalty of 100 cycles. Exercise 4. [30 Marks The following tables summarizes the instructions present in some program (Table 1) as well as two different processors (Table 2). Operation ALU Load Store Branch Instruction Count 2000 1000 600 400 Operation ALU Load Store Branch Processor 1 Processor 2 3 1 4 6 3 3 2 2 Table 1: Program Instructions Table 2: Processor Instruction Cycles (a) [5 Marks] Calculate the ideal CPI of this program running on Processor 1. (b) [5 Marks] Calculate the ideal CPI of this program running on Processor 2. (c) (5 Marks) Assuming that Processor 1 operates at 2.8 GHz and Processor 2 operates at 2.4 GHz calculate the CPU time for the program when run on each processor. On which processor is the program faster? (Hint: for easy calculations, 1GHz = 1 x 10Hz) (d) [5 Marks] In terms of the three factors calculating CPU time (instruction count, CPI, clock frequency) explain why the processor from part (c) is the faster one. How could a programmer change the program described in Table 1 so that it would run faster on the other processor? (e) [10 Marks Calculate the CPU time of the program described in Table 1 running on Processor 1 (at 2.8 GHz) when also considering memory stall cycles (and thus have CPU time calculated using CPIstall). Assume this processor has one level of cache, an instruction miss rate of 2%, a data miss rate of 5% and a miss penalty of 100 cycles
