Consider three different processors P1, P2, and P3...

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Study Guide CECS 341 Different types of languages: Assembly language: language used by compilers Machine language: language used by the computer High level languages: language used by programmers Levels of Languages High-level language 1. Portable/convenient Assembly language 1. Textual representation of instructions Hardware representation 1. Encoded instructions/data 2. All 1’s and 0’s (bits) Instruction Set Architecture 1. Assembly/machine code Microarchitecture 1. ISA implementation Response time an throughtput Response time 1. How long it takes to do a task Throughput 1. Total work done per unit time Elapsed time 1. Total response time, including all aspects Performance Performance = 1/Execution Time “X is n time faster than Y” Example: time taken to run a program 10s on A, 15s on B Execution TimeB / Execution TimeA = 15s / 10s = 1.5 So A is 1.5 times faster than B CPU time CPU time = CPU clock cycles * clock cycle time = CPU clock cycles/ Clock rate Clock Cycles Clock cycles = Instruction count * cycles per instructions
CPU time = Instruction count * CPI * Clock cycle time = Instruction count * CPI / Clock Rate Clock Rate Clock rate = 1/ Clock cycle time Performance should be high because that computer will be better Eg: 1 Consider three different processors P1, P2, and P3 executing the same instruction set. P1 has a 3 GHz clock rate and a CPI of 1.5. P2 has a 2.5 GHz clock rate and a CPI of 1.2. P3 has a 3.5 GHz clock rate and has a CPI of 2.0. a Which processor has the highest performance expressed in instructions per second? b We are trying to reduce the execution time by 30% but this leads to an increase of 20% in the CPI. What clock rate should we have to get this time reduction?

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