Review 1: Computer Architecture

\(10^{-12}\) pico
\(10^{-9}\) nano
\(10^{-6}\) micro
\(10^{-3}\) milli
\(10^{3}\) Kilo
\(10^{6}\) Mega
\(10^{9}\) Giga
\(10^{12}\) Tera

Performance

Response Time: Time taken to do a particular task

Throughput: Total workdone per unit time

\[Performance = \frac{1}{\text{Execution Time or Response Time}}\]


\[\frac{Performance_{x}}{Performance_{y}} = \frac{Execution_{y}}{Execution_{x}}\]

Clock Period: Duration of a clock cycle. e.g., 250 ps (picosecond)

Clock frequency: Number of clock cycles per second. e.g., 40 GHz or \(40\times{10}^{9}\frac{cycles}{second}\)

\[\text{Program CPU Time} = \text{# of CPU Clock Cycles}\times\text{Clock Cycle Time or Clock Period} = \frac{\text{CPU Clock Cycles}}{\text{Clock Rate}}\]

However,

\[\text{CPU Clock Cycles}=\text{Instruction count of a program(IC)}\times\text{# of cycles per instruction(CPI)}\]

Therefore,

\[\text{Program CPU Time}=\frac{IC\times{CPI}}{\text{Clock Rate}}\]

Weighted Average CPI:

\[CPI_(\text{weighted avg})=\frac{\sum_{i}^{}IC_i\times{CPI_i}}{\text{Total Instruction Count}}\]

MIPS(Million Instructions Per Second):

\[MIPS=\frac{\text{Instruction Count}}{\text{CPU Time}\times{10}^6}\]

Substituting CPU Time in the above equation,

\[MIPS=\frac{\text{Clock Rate}}{\text{CPI}\times{10}^6}\]