Study Guide CECS 341.docx - Study Guide CECS 341 Different...

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?