1. Chapter 1: Introduction CSS503 Systems Programming
Prof. Munehiro Fukuda
Computing & Software Systems University of Washington Bothell
CSS503
Chapter 1: Introduction

2. Defining Operating Systems
Goals
Execute user programs and make solving user problems easier
Making the computer system convenient to use
Using computer hardware in an efficient manner
Definitions
Resource allocator – manages and allocates resources
Control program – controls the execution of user programs and operations of I/O devices
Kernel – the one program running at all times (all else being application programs)
CSS503
Chapter 1: Introduction

3. Computer System Components
CSS503
Chapter 1: Introduction

4. Operating-System Operations
Protection
Distinguishing user and kernel
I/O Management
Asynchronous I/Os
Process Management
Launching, synchronizing, and terminating programs
Memory Management
Giving each task a independent logical address space
Storage Management
Giving logical views of disk spaces, (i.e. directories and files)
CSS503
Chapter 1: Introduction

5. Chapter 1: Introduction
Dual-Mode Operation
User Mode: Non-privileged operations only
Kernel Mode: All operations (including I/O instructions)
Transition
User to Kernel: Interrupts, system calls, and traps
Kernel to User: A special instr. such as IRET
CSS503
Chapter 1: Introduction

6. Chapter 1: Introduction
I/O Management
requesting process
waiting
device driver
Interrupt handler
Hardware
data transfer
user
kernel
time
Faster CPU/Memory versus Slower I/Os
Synchronous I/O or CPU I/O
CPU takes care of All I/O operations.
Polling wastes CPU time.
CSS503
Chapter 1: Introduction

7. I/O Management (Cont’d)
a requesting process
replaced with another one
device driver
Interrupt handler
Hardware
data transfer
user
kernel
time
interrupts
DMA
Device interrupts and DMA
Asynchronous I/O
DMA takes care of I/O data transfers.
Devices interrupt CPU when they are ready.
CSS503
Chapter 1: Introduction

8. Chapter 1: Introduction
Process Management
Process Control Block and Logical Address
A program in execution
Process needs:
CPU, memory, Files, I/Os etc.
OS must supports:
Creation: loading it in memory
Synchronization/communication: having a process wait for another.
Termination: clean it up from memory
Process ID
Text
(Code + Global Data)
UID GID EUID EGID
Directory Entry
TTY
Heap
Signal Dispatch
Table
Memory Map
stdin
priority 1
stdout
Intr. mask 2
stderr
registers 3
Stack
CPU Status
File Descriptors
trek.txt
CSS503
Chapter 1: Introduction

9. Chapter 1: Introduction
Memory Management
Process A’s Logical Address
Physical Address Space
Providing each process with a logical address space
Mapping logical address to physical address (paging and segmentation)
Facilitating virtual memory using disk
Text
Heap
Process B’s Logical Address
Text
Heap
Process C
Text
Stack
Heap
Stack
Virtual Memory in Disk
Stack
CSS503
Chapter 1: Introduction

10. Chapter 1: Introduction
Storage Management
Process 1 1 2 3
stdin
stdout
stderr
Disk partitioning
Allowing multiple file systems
File and directory management
Logical to physical mapping
File operations
open, read, write, seek, close
Boot sector, partition table
Superblock 1
File
descriptors
File table entry
inode
Linux
Process 2 1 2 3
stdin
stdout
stderr
Superblock 2
File
descriptors
NTFS
CSS503
Chapter 1: Introduction

11. Chapter 1: Introduction
Memory Hierarchy
Important Rules on Storage Operations
Inclusion property
Memory coherence
Level
Size
Speed
(ns)
Managed by
Registers
1KB
0.25 ~ 0.5
Compiler
Cache
16MB
0.5 ~ 25
Hardware
Main memory
16GB
80 ~ 250 OS
Hard disks
Several TB
5000
CPU
Core 1
Core 2
Reg
Reg L1 L1
L2 Cache
Main Memory
Hard disks
Hard disks
Hard disks
CSS503
Chapter 1: Introduction

12. Chapter 1: Introduction
Discussion
Solve Text Exercises:
1.6 (Privileged Instructions)
1.8 (CPU Mode)
1.20 (DMA)
1.22 (Cache Memory)
CSS503
Chapter 1: Introduction