week - 09

PINTOS - Threads

PintOS Document

Assignment 1 - Alarm clock.

An alarm is a kernel internal function that restarts the calling process after a predetermined time interval.

devices/timer.c에 구현 된 timer_sleep() 함수 Busy waiting을 피하도록 재구현

Implementing "Sleep and Wake up"

Keyword

Busy waiting -> do empty loop waiting for entrying critical section

blocked queue -> if sem == 0
process do self-blocked and insert PCB in wait queue
if sem be positive
queue pop to ready queue

semaphore based on mutex(mutual exclusion)
semaphore can be mutex, can't converse.

• binary semaphore(mutex) - single resource
• counting semaphore - identical resources

mutex, semaphore usage in C
dining philosophers
consumer producer
Later....

Deadlock

Deadlock prevention with Banker's algorithm
Later...

Starvation

similar with Deadlock,
but status is ready
with poor priority

CPU Scheduling

Purpose

• Maximize CPU utilization
• Minimize response and waiting time of process

Scheduling Algorithm is deciding which process will own the CPU.