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[2011-2] 시스템 프로그래밍
Class 2 : Introduction
담당교수 : 최 윤 정
2011. 8.31
Introduction

Compilation Process

Preprocessing Phase


Compilation Phase


Modifies the original C program according to the directives (#)
Translates the C program into Assembly-language program
Assembly Phase

Transforms the Assembly-language program into Machine language
programs

Linking Phase

Merge all the necessary object files to generate executables.
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printf.o
hello.c
Source
program
(text)
Prehello.i
processor
(cpp)
Modified
source
program
(text)
Compiler
(cc1)
hello.s
Assembly
program
(text)
Assembler hello.o
(as)
Relocatable
object
programs
(binary)
Linker
(ld)
hello
Executable
object
program
(binary)
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Hardware Organization

Buses



I/O Devices

The system’s connection to the external world

In the example, keyboards, mouse, display, disk drive
Main Memory


Carry bytes of information back and forth between components
Temporary storage device holding both a program and the data while the processor executes the program
Processor

CPU interprets instructions stored in main memory

PC (program counter) points at some machine language instructions in main memory

Register File and ALU

CPU executes very simple operations

Load (from MM to Register), Store (from Register to MM),
Update (Copy bytes to ALU, stores the result in a register),
I/O Read (from I/O device to Register), I/O Write (from Register to I/O device),
Jump (change PC value using a word extracted from the instruction), etc.
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Hardware
Organization
CPU
Register file
PC
ALU
System bus
Memory bus
Main
memory
I/O
bridge
Bus interface
I/O bus
USB
controller
MouseKeyboard
Graphics
adapter
Disk
controller
Display
Disk
Expansion slots for
other devices such
as network adapters
hello executable
stored on disk
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Running “hello, world” – reading k/b
CPU
Register file
PC
ALU
System bus
Memory bus
Main "hello"
memory
I/O
bridge
Bus interface
I/O bus
USB
controller
Mouse Keyboard
User
types
"hello"
Graphics
adapter
Disk
controller
Expansion slots for
other devices such
as network adapters
Display
Disk
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Running
“hello,
world”
loading
CPU
Register file
PC
ALU
System bus
Memory bus
"hello,world\n"
Main
memory
hello code
I/O
bridge
Bus interface
I/O bus
USB
controller
Mouse Keyboard
Graphics
adapter
Disk
controller
Display
Disk
Expansion slots for
other devices such
as network adapters
hello executable
stored on disk
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Running “hello, world” - writing
CPU
Register file
PC
ALU
System bus
Memory bus
Main "hello,world\n"
memory
hello code
I/O
bridge
Bus interface
I/O bus
USB
controller
Mouse Keyboard
Graphics
adapter
Disk
controller
Display
"hello,world\n"
Disk
Expansion slots for
other devices such
as network adapters
hello executable
stored on disk
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Caches and Memory Hierarchy
L0:
Registers
Smaller,
faster,
and
costlier
(per byte)
storage
devices
L1: On-chip L1
cache (SRAM)
L2:
L3:
Larger,
slower,
and
cheaper
(per byte)
storage
devices
L5:
CPU registers hold words retrieved
from cache memory
L4:
Off-chip L2
cache (SRAM)
L1 cache holds cache lines retrieved
from the L2 cache
L2 cache holds cache lines
retrieved from memory
Main memory
(DRAM)
Main memory holds disk
blocks retrieved from local
disks
Local secondary storage
(local disks)
Local disks hold files
retrieved from disks on
remote network servers
Remote secondary storage
(distributed file systems, Web servers)
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Operating System
Application programs
Software
Operating system
Processor
Main memory
I/O devices
Hardware
System Layers
Processes
Virtual memory
Files
Processor
Main memory
I/O devices
Abstractions by O/S
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Operating System

Processes

Operating system’s abstraction for a running program

Multiple programs can run concurrently on the same system

Concurrency provided by context switch

Context: State information that the process needs to run including values
in PC, registers, and main memory
shell
hello
process
process
Time
Application code
OS code
Context
switch
Application code
OS code
Application code
Context
switch
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Operating System
 Threads

Execution units in a process

Each thread runs in the context of the process and shares the
same code and global data

Easier to share data between multiple threads than processes

Typically more efficient than processes
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Operating System
 Virtual Memory

Abstraction that provides each process with the illusion that it
has exclusive use of the main memory

Process’s uniform view of memory
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Operating System
0xffffffff
0xc0000000
Kernel virtual memory
User stack
(created at runtime)
Stack: Top of the user’s address
Memory
Shared Libraries: Holds code
invisible to
user
code
and data
for shared libraries
such as C standard library and
math library. Related to dynamic
space. Used to implement
linking (CH 7).
function calls. Expands and
Kernel is the part of the operating
contracts dynamically during the
Heap: Expands and contracts
0x40000000
execution by function calls.
dynamically at run time as a
Memory mapped region for
shared libraries
memory. Top ¼ of the virtual
memory
reserved
kernel.
Program
Code for
andthe
Data:
result of calls to C standard
library routines such as malloc
Run-time heap
(created at runtime by malloc)
and free.
Read/write data
Read-only code and data
0x08048000
– 14 –
printf()
system that function
is always resident in
0
Unused
Applications
are not allowed
Initialized directly
from the
access.
contents of an executable object
file
Loaded from the
hello executable file
Operating System
 Files
 A sequence of bytes.
 Every I/O device is modeled as a file.
 A network is another I/O device to O/S.
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Conclusion

A Computer system consists of hardware and system software.

Processors read and interpret binary instructions stored in main
memory.

Storage devices that are higher in the hierarchy are faster. Can
help performance optimization.

Operating system kernel serves an intermediary between the
application and hardware.

O/S provides three fundamental abstractions: Files for I/O devices,
VM for MM and disks, Processes for Processor, MM and I/O
devices.

Network is just another I/O device.
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