1. LINUX System : Lecture 7
Lecture notes acknowledgement : The design of UNIX Operating System

2. Architecture of the UNIX
user programs
libraries
user Level
kernel Level
system call interface
file subsystem
process
control
subsystem
inter-process
communication
scheduler
memory
management
buffer cache
좌측에 파일서브시스템과 우측에 프로세스 서브시스템이 가장 핵심되는 축이 된다.
3종류의 레벨로 나뉘어져 있다 – user level, kernel level, hardware level
device drivers
character
block
hardware control
kernel Level
hardware Level
hardware

3. System calls & Libraries
user programs
libraries
trap
user Level
kernel Level
system call interface
system call interface
file subsystem
process
control
subsystem
inter-process
communication
scheduler
memory
management
buffer cache
device drivers
character
block
hardware control
kernel Level
hardware Level
hardware

4. System calls & Libraries
System call library
OS service in the form of C function call
Standard library, User library
Linked with the programs at compile time and are part of the user program

5. File Subsystem (1) process control libraries system call interface
user programs
libraries
trap
user Level
kernel Level
system call interface
file subsystem
process
control
subsystem
inter-process
communication
scheduler
memory
management
buffer cache
device drivers
character
block
hardware control
kernel Level
hardware Level
hardware

6. File Subsystem (2) Managing files and structures of file system
Allocating file space
Administering free space
Controlling access to files
Retrieving data for users
Interact with set of system calls
open, close, read, write, state, chown, chmod …

7. Buffering Mechanism (1)
user programs
libraries
trap
user Level
kernel Level
system call interface
file subsystem
process
control
subsystem
inter-process
communication
scheduler
memory
management
buffer cache
device drivers
character
block
hardware control
kernel Level
hardware Level
hardware

8. Buffering Mechanism (2)
Interact with block I/O device drivers to initiate data transfer to and from kernel.

9. Process Control Subsystem (1)
user programs
libraries
trap
user Level
kernel Level
system call interface
file subsystem
process
control
subsystem
inter-process
communication
scheduler
memory
management
buffer cache
device drivers
character
block
hardware control
kernel Level
hardware Level
hardware

10. Process Control Subsystem (2)
Managing process structures (proc table, u table,…)
Process scheduling
Interprocess communication (IPC)
Memory management
Responsible for process synchronization.
Communicate with file subsystem
Loading a file into memory for execution
Interact with set of system calls
fork, exec, exit, wait, brk, signal …
파일시스템과 프로세스 컨트롤 시스템간의 서로 연계되는 때는 프로그램 실행을 위해서 메모리에 프로그램을 로딩할 때이다.

11. Process Control Subsystem (3)
Memory management module
Control the allocation of memory to a process
Scheduler module
Allocate the CPU to processes
Interprocess communication
There are several forms.

12. Hardware Control (1) process control libraries system call interface
user programs
libraries
trap
user Level
kernel Level
system call interface
file subsystem
process
control
subsystem
inter-process
communication
scheduler
memory
management
buffer cache
device drivers
character
block
hardware control
kernel Level
hardware Level
hardware

13. Hardware Control (2)
Responsible for handling interrupts and for communicating with the machine.
Devices such as disks or terminals may interrupt the CPU while a process is executing

14. Topics to be covered File subsystem Process control subsystem
(Memory Management)
Signal
IPC (Inter-Process Communication), Synchronization
UNIX System Programming (System Calls)

15. Reference Books The design of the UNIX Operating System, M. J. Bach
Advanced Programming in the Unix Environment, 2nd Edition, W. R. Stevens, S. A. Rago