Operating System
Evolution of an Operating
System
Simple Batch Systems
The Monitor
Desirable Hardware
Features
Multiprogrammed Batch
Systems
Multiprogrammed Batch
Systems
Example:
Three Jobs Submitted
Advantages of
Multiprogramming
Time Sharing Systems
(TSS)
Pseudo-Parallelism
Process
Process Model
Processes and Interrupt
Handling Implementation
Process Scheduling
Scheduling Methods
Concurrency
Event-driven
Environments:
Window Interface Environments
Concurrency:
Co-routines
Co-routines (cont.)
Threads
Benefits of Threads vs
Processes
Benefits of Threads
Problem: Inconsistent
Data Views
Threads States
User-Level Threads (ULT)
Threads library
Kernel activity for
User-Level Threads
Advantages and
Inconveniences of ULT
Kernel-Level Threads
(KLT)
Advantages and
Inconveniences of KLT
Combined ULT/KLT
Approaches
Language with Support for
Concurrency: Ada
Ada Rendezvous
Stacks in a Concurrent
Program
PThreads (POSIX Threads)
Problems with Concurrent
Execution
An Example
The Critical Section
Problem
The Critical Section
Problem
Framework for Analysis of
Solutions
Software Solutions:
Algorithm 1
Software
Solutions:
Algorithm 2
Software
Solutions:
Algorithm 3
Semaphores
Semaphores
Semaphore Operations
(atomic)
Semaphores: Observations
Semaphores and Critical
Sections
Process
Synchronization:
Monitors
Monitor
Monitor Example:
Producer-Consumer
Managing Memory within a
Program
Heap
Garbage Collection