LINUX System : Lecture 7

1. LINUX System : Lecture 7 Bong-Soo Sohn Lecture notes acknowledgement : The design of UNIX Operating System

2. process control subsystem inter-process communication scheduler memory management character block device drivers kernel Level hardware Level Architecture of the UNIX user programs libraries trap user Level kernel Level system call interface file subsystem buffer cache hardware control hardware

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

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

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

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. process control subsystem inter-process communication scheduler memory management character block device drivers kernel Level hardware Level Hardware Control (1) user programs libraries trap user Level kernel Level system call interface file subsystem buffer cache hardware control 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 • UNIX Internals : The New Frontiers, U. Vahalia • Advanced Programming in the Unix Environment, 2nd Edition, W. R. Stevens, S. A. Rago