Performance Items Flashcards
What is CPU Frequency
cycles/second -
Clock rate- how many pauses are issues per second.
CPU cycle is the amount of time CPU preforms fetch, decode, excute.
CPU clock device
a device (hardware) that emits synchronization pauses. When such signal arrives to CPU component, CPU component does one unit of work
CPU Cycle
time between two synchronization pulses
What is the measurement unit of CPU frequency? What exactly does it measure?
the frequency of synchronization pulses in the CPU. cycles per second.
Does CPU frequency affect the computer performance?
The higher the frequency, the higher the computer performance. More instructions are done pers second.
Name other factors that define computer performance
number of cores, CPU architecture, RAM performance, cache efficiency and speed
What are the software factors that affect execution speed?
program efficiency, compiler efficiency
What hurts program execution speed more: weak hardware or inefficient program code?
Inefficent Program Code
What is the most reliable way to compare performance of different computers?
Benchmarks
Benchmark Suites
fixed program that is used by different computers to compare computer performance.
Set of benchmarks to get a well-rounded performance effiency-Different benchmarks stress different components, like CPU, memory, and storage.
Prefixes k, M, G, ki, Mi, Gi, p, n.
K = 1000 = 10^3
M = 1,000,000 = 10^6
G = 1,000,000,000 = 10^9
p(pico = 10^-12
n= 10^-9
micro = 10^-6
mili=10^3
KB = 2^10 = 1024
MB = 2^20= 1,000,000+
GB = 2^30
How do you compare execution times of two programs?
no running time difference, only ratio
Avergae CPI
average_CPI = total_number_of_cycles /dynamic_intsr_count
What is dynamic instruction count? What is the measurement unit dynamic instruction count?
Actual number of instructions for CPU to finihs the whole program.
UNIT: Instruction:
Equations that connect execution time, total number of cycles, CPU frequency (also known as clock rate), cycle duration, average CPI, dynamic instruction count.
LOOK AT NOTION
Powerwall
powerwall is about the physical limitations that prevent engineers from raising CPU frequency
Why do we want to raise CPU frequency
The higher the frequency, the higher the computer performance, but the more heat the CPU is generating
What prevents engineers from raising CPU frequency?
more heat the CPU is generating. CPU stops functioning corrrectly.
What are the advantages of using lower voltage?
lower heat generation
longer battery life
lower electricity bills
Transistor
small CPU components
What is transistor leakage?
transistor imperfection that doesn’t allow to use transistors with a very low voltage
Formula for
CPU time = Total CPU clock cyles/clock rate (cycle/sec)
CPI
Cycles per Instruction
Total Cycles
Average
CPI (cylcer/instr) * instruction_Count
