COMP411: Representing Information, Performance and Trends

Consider a computer running a program that requires 240 seconds, with 80 seconds spent executing FP instructions, 80 seconds spent executing INT instructions, 45 seconds spent executing branch instructions, and 35 seconds executing load/store instructions. By how much is the total time reduced if the time for FP operations is reduced by 20%? Time spent executing floating point: ________ New execution time: _________ Percent reduction: _______%

64,224, 6.67

If computer A's performance is 5/3 times greater than that of Computer B, then by what % is B's execution time longer than that of A

67%?

Which of the following are not input/output devices in a computer system? Respond with all: A. Wifi B. mouse C. touchscreen D. speakers E. processor F. monitor G. battery H. hard drive I. memory

processor, battery, memory

Suppose we are interested in comparing two computer systems on the basis of both performance and money. Which of the following compound metrics could be valid ones to use? A. square_root(Performance) / Cost B. Performance / Power C. Performance + Cost D. (Performance^2) / Cost E. Performance * Cost F. (Performance^2) * Power

square_root(Performance) / Cost, Performance / Power, (Performance^2) / Cost

Suppose we are interested in comparing two computer systems with different ISAs on the basis of both performance. Which of the following metrics could be valid ones to use? A. Throughput of a test workload B. clock rate C. Execution time of a set of benchmark applications D. cycles per instructions

throuput of a test workload, execution time of a set of benchmark

Suppose person A weighs 100 kg, and person B weighs 150 kg. A is _______ times as heavy as B

.67

George the l33t h4x0r figures out he can make the same program, but it takes: Type A 1E9 instructions 1 CPI Type B 3E9 instructions 3 CPI Type C 4E9 instructions 5 CPI He has never taken COMP411 and can't figure out how long it will take to run the program. How long does it take to run this new program?

15 seconds

If a program has 4e9 (i.e., 4x10^9) instructions with an average CPI of 2.0 and completes execution in 1 second, what is the clock speed of the processor?

8 GHz

Consider three different processors, P1, P2 and P3, executing the same instruction set: P1 has a 3.0 GHz clock rate and a CPI of 2.5 P2 has a 7.5 GHz clock rate and a CPI of 1.5 P3 has a 8.0 GHz clock rate and a CPI of 2.0 P1: 1.2e9 instructions per second P2: 5e9 instructions per second P3: 4e9 instructions per second Which processor has the lowest performance expressed in instructions per second?

P1

Which of the following factors do not affect the user CPU time of a program? A. size of the disk drive B. computer's instruction set architecture C. speed of the operating system in performing input-output operations D. choice of compiler E. activity of other programs running concurrently F. clock speed/frequency G. speed of the wifi network connection H. actual values of data inputs I. average CPI of the program's instrcutions J. Choice of programming language K. choice of algorithm

size of the disk drive, speed of the operating system in performing input-output operations, activity of other programs running concurrently, speed of the wifi network connection

Marceline is also very concerned about power consumption. Her new memory requires twice the voltage as the previous version of memory. By what factor has the static power consumption increased? By what factor has the dynamic power consumption increased?

2 X speedup 4 X speedup

Suppose person A weighs 100 kg, and person B weighs 150 kg. B is _______% heavier than A

50%

Suppose a program contains the following mix of instructions: 25% type A, 50% type B, and 25% type C. Type A instructions have CPI of 4, Type B have CPI of 6, and Type C have CPI of 8. Then, the average CPI for the program

6

Compilers can have a profound impact on the performance of an application. Assume that for a program, compiler A results in a dynamic instruction count of 1.50E9 and has an execution time of 2.4 seconds, while compiler B results in a dynamic instruction count of 2.5E9 and an execution time of 3.5 seconds. Assume the compiled programs are now run on two different processors --- Processor A runs Compiler A's code and Processor B runs Compiler B's code --- and that the average CPIs of the two programs are as they were in the previous question. However, suppose that the execution times on the two processors are now equal. What is ratio of clock speed of Processor A to the clock speed of Processor B? Give the answer as a factor, not %. Processor A's clock speed / Processor B's clock speed:

.68

Considering that processor P1 is executing a sequence of 1.5E9 instructions and that the CPI of processors P1 and P2 is the same as specified above (i.e., 2.5 and 1.1, respectively), determine the number of instructions that P2 can execute in the same time that P1 needs to execute 1.5E9 instructions. Execution time for P1: Equivalent number of instructions on P2:

.75, 2.05E9

Suppose a 2 GHz processor runs an unknown program, with an average CPI of 4.0. You record that the CPU time taken to execute the program is 2 seconds. How many instructions were executed in running this program?

1*10^9

Consider three different processors, P1, P2 and P3, executing the same instruction set: P1 has a 3.0 GHz clock rate and a CPI of 2.5 P2 has a 7.5 GHz clock rate and a CPI of 1.5 P3 has a 8.0 GHz clock rate and a CPI of 2.0 P1: 1.2e9 instructions per second P2: 5e9 instructions per second P3: 4e9 instructions per second The processors each execute a program in 10 seconds. How many cycles have passed for each processor? P1: _____ instructions P2: _____ instructions P3: _____ instructions

1.2E10, 5E10, 4E10

Consider three different processors, P1, P2 and P3, executing the same instruction set: P1 has a 3.0 GHz clock rate and a CPI of 2.5 P2 has a 7.5 GHz clock rate and a CPI of 1.5 P3 has a 8.0 GHz clock rate and a CPI of 2.0 What is the rate of instructions executed for each processor? Enter the full number in either scientific notation or normal notation. P1: _______ instructions per second P2: ______ instructions per second P3: ______ instructions per second

1.2E9, 5E9, 4E9

Suppose person A weighs 100 kg, and person B weighs 150 kg. B is _______ times as heavy as A

1.5

Compilers can have a profound impact on the performance of an application. Assume that for a program, compiler A results in a dynamic instruction count of 1.50E9 and has an execution time of 2.4 seconds, while compiler B results in a dynamic instruction count of 2.5E9 and an execution time of 3.5 seconds. Find the average CPI for each program given that the processor has a clock cycle time of 1 nano-seconds (i.e., the clock rate is 1 GHz).

1.6,1.4

Suppose the execution time of a program is 175 s, consisting of 100 s spent executing floating-point instructions and 75 s spent executing the rest. If an improvement to the design speeds up floating-point instructions by a factor of 4 (without affecting the speed of other instructions), by what factor is the performance of the entire program faster now?

1.75X

Consider two different implementations of the same instruction set architecture (P1 and P2). The instructions can be divided into four classes according to their CPI (class A, B, C, and D). P1 with a clock rate of 3 GHz and CPIs of 1, 2, 3, and 4 for each class respectively. P2 with a clock rate of 2.5 GHz and CPIs of 2, 2, 3, and 3 for each class respectively. Answer the following questions given a program with a dynamic instruction count of 2.0E6 instructions divided into classes as follows: Class A 15% Class B 20% Class C 35% Class D 30% How long does it take each processor to execute the entire program? Note the unit "seconds" is provided. If your answer is "4 milliseconds", enter "0.004" or "4e-3" in the space for the answer.

1.8E-3, 2.1E-3

Suppose machine M1 is 3 times faster than machine M2. How much time does M2 take to execute a program if M1's performance on the same program is 1 / (6 seconds) ?

18 seconds

Suppose a program is executed in 3 seconds on a computer which has a 4 GHz clock. The program executes 6 billion (6e9) instructions in total. What is the average CPI?

2

A program uses the following type of instructions & CPIs Type A 5E9 instructions 1 CPI Type B 2E9 instructions 3 CPI Type C 1E9 instructions 5 CPI What is the average CPI of the program? If the program runs on a computer a clock frequency of 2 GHz, how long will it take to run the program.

2 CPI 8 seconds

Compilers can have a profound impact on the performance of an application. Assume that for a program, compiler A results in a dynamic instruction count of 1.50E9 and has an execution time of 2.4 seconds, while compiler B results in a dynamic instruction count of 2.5E9 and an execution time of 3.5 seconds. For the same program as in the previous two questions, a new compiler is developed that uses only 6.0E8 instructions and has an average CPI of 1.8. What is the speedup of using this new compiler versus using compiler A or B on the original processor (with 1 GHz clock)? Express each answer as a factor, not %.

2.22,3.24

A CPU has a voltage of 5V, a clock frequency of 2 GHz, a leakage current of 20 mA, 2 GB of RAM, a cache size of 2 MB, dual boots Windows 7 and Debian, and is located in a climate controlled room in a green case. It executes instructions of three types: Class A, B and C. The CPI of each instruction class, along with their frequency is: Class A: CPI=2, freq=50% Class B: CPI=4, freq=25% Class C: CPI=1, freq=25% What is the average CPI of the processor?

2.25 CPI

A certain program spends 80% of its total execution time on writing to disk. Your manager wants the program to run twice as fast. You convince your manager that you need to buy a new disk to make the program run faster. How much faster should the new disk be (answer to 2 decimal places)?

2.67

P1 has a clock rate of 5 GHz, average CPI of 2.5, and requires the execution of 5.5E9 instructions. P2 has a clock rate of 3 GHz, an average CPI of 1.1, and requires the execution of 2.0E9 instructions One usual fallacy is to consider the computer with the higher clock rate as having the higher performance. Check if this is true for P1 and P2.

2.75, .733

Consider two different implementations of the same instruction set architecture (P1 and P2). The instructions can be divided into four classes according to their CPI (class A, B, C, and D). P1 with a clock rate of 3 GHz and CPIs of 1, 2, 3, and 4 for each class respectively. P2 with a clock rate of 2.5 GHz and CPIs of 2, 2, 3, and 3 for each class respectively. Answer the following questions given a program with a dynamic instruction count of 2.0E6 instructions divided into classes as follows: Class A 15% Class B 20% Class C 35% Class D 30% What is the average CPI for each processor?

2.8, 2.65

If Computer A's performance is 5/4 times greater greater than that of Computer B, then then by what % is A's execution time smaller than that of B?

20%

Processor A has a clock rate of 3.0 GHz and voltage of 1.10 V. Assume that, on average, it consumes 20 W of static power and 80 W of dynamic power. Processor B has a clock rate of 3.8 GHz and voltage of 0.75 V. Assume that, on average, it consumes 20 W of static power and 55 W of dynamic power. Find the percent of the total dissipated power comprised by static power for each processor.

20%, 26.7%

Consider three different processors, P1, P2 and P3, executing the same instruction set: P1 has a 3.0 GHz clock rate and a CPI of 2.5 P2 has a 7.5 GHz clock rate and a CPI of 1.5 P3 has a 8.0 GHz clock rate and a CPI of 2.0 P1: 1.2e9 instructions per second P2: 5e9 instructions per second P3: 4e9 instructions per second The processors each execute a program in 10 seconds. How many cycles have passed for each processor? P1: _____ cycles P2: _____ cycles P3: _____ cycles

30E9, 75E9, 80E9

Suppose person A weighs 100 kg, and person B weighs 150 kg. A is __________% lighter than B

33%

Processor A has a clock rate of 3.0 GHz and voltage of 1.10 V. Assume that, on average, it consumes 20 W of static power and 80 W of dynamic power. Processor B has a clock rate of 3.8 GHz and voltage of 0.75 V. Assume that, on average, it consumes 20 W of static power and 55 W of dynamic power. For each processor find the capacitive load, C. The units are Farads (F), already supplied; do not include any units in your answer space. (For example, if your answer is 1 nF, enter 1e-9 in the blank.)

4.4E-8,5.1E-8

A CPU operating at 2 V supply voltage consumes 10 W of static power and 40 W of dynamic power. Suppose it is now operated at 1 V supply voltage instead, with all other quantities (i.e., switching frequency, total capacitance, leakage current) remaining the same. What is the new power consumption of the CPU? static power = _________ W and dynamic power = _______ W.

5,10

We are trying to reduce the execution time by 30% but the hardware modifications we made had a side effect of increasing the CPI by 20%. What clock rate should we have to get this time reduction? Note: The supplied unit is Hz not GHz. Please do not enter units in the blank space. If you want to enter 2 GHz as your answer, enter "2E9" in the space provided, and do not enter "Hz". P1: _______ clock ticks per second (Hz) P2:________ clock ticks per second (Hz) P3: ________ clock ticks per second (Hz)

5.1E9, 12.7E9, 13.6E9

Consider two different implementations of the same instruction set architecture (P1 and P2). The instructions can be divided into four classes according to their CPI (class A, B, C, and D). P1 with a clock rate of 3 GHz and CPIs of 1, 2, 3, and 4 for each class respectively. P2 with a clock rate of 2.5 GHz and CPIs of 2, 2, 3, and 3 for each class respectively. Answer the following questions given a program with a dynamic instruction count of 2.0E6 instructions divided into classes as follows: Class A 15% Class B 20% Class C 35% Class D 30% How many cycles will each processors use to execute the entire program?

5.6E6, 5.3E6

In COMP 541, students create processors which are powered by a USB port. A standard USB port supplies up to 1A of 5V (DC) power. Assume a leakage current of 20 mA and a capacitance of 20 nF (1E9 nF = 1F), and an overall efficiency of 50%. What is the maximum frequency that the processor can run at? If we step down the voltage inside the processor by half, how much can the frequency be increased? Assume that stepping down the voltage by half also causes the CPI to increase by 1.25, how much has the performance measured by MIPS changed?

9.6 MHz 39 MHz 3.25 X speedup

Which of the following laws state that the number of transistors on an ideal-sized chip doubles every couple of years? A. Amdahl's Law B. Cole's Law C. Moore's Law D. Brook's Law

Moore's Law

Suppose we can reduce the time only for INT operations. By how much should the time for INT operations be reduced so that the total execution time is reduced by 20% (compared to the original)? New execution time: Time spent executing non-INT instructions: Time spent executing INT instructions: Percent reduction in execution time of INT instructions: %

New execution time: 192 seconds Time spent executing non-INT instructions: 160 seconds Time spent executing INT instructions: 32 seconds Percent reduction in execution time of INT instructions: 60 %

Suppose we want the total execution time to be reduced by 25% by reducing only the time for L/S instructions? We will determine if that is feasible in the next question, but first calculate the following values: Required execution time (after 25% reduction): Execution time of non-L/S instructions:

Required execution time (after 25% reduction): 180 seconds Execution time of non-L/S instructions: 205 seconds