Download chapter 1: operating system fundamentals

CHAPTER 1: OPERATING SYSTEM
FUNDAMENTALS
What is an operating system?
• A collection of software modules to assist programmers in enhancing
system efficiency, flexibility, and robustness
• An Extended Machine from the users’ viewpoint
• A Resource Manager from the system’s viewpoint
What are the primary functions of an operating system?
• multiplexing the processor(s)
• scheduling processes
• coordinating interaction among processes, interprocess communication
and synchronization
• managing system resources (I/O, memory, data files)
• enforcing access control and protection
• maintaining system integrity and performing error recovery
• providing an interface to the users
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Evolution of modern operating systems
1. Centralized operating system: resource management and extended machine to support Virtuality
(a) Resident Monitor (RM) - user=operator, single process
(b) Batch Systems - user 6= operator, single → multiple processes
(c) Timesharing Systems - interactive, multiple processes
(d) Personal Computers - user=operator, single → multiple processes
2. Network operating system: resource sharing to achieve Interoperability
3. Distributed operating system: a single computer view of a multiplecomputer system for Transparency
4. Cooperative autonomous system: cooperative work with Autonomicity
A spectrum of modern operating systems
1st
Decreasing Degree of Hardware and Software Coupling
3rd
4th
2nd
centralized
operating
distributed
operating
cooperative
autonomous
network
operating
system
system
system
system
Decreasing Degree of Transparency
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Operating system structuring methods
• modularization
• vertical partitioning (layered one-in-one-out structure)
• horizontal partitioning
• client/server model
• minimal (or micro) kernel
• subsystem with API and SPI
Example of OS Partitioning:
Applications
accounting
word processing
Subsystems
programming environment
Utilities
compiler
System Services
file system
Kernel
manufacturing
database system
command interpreter
memory manager
library
scheduler
CPU multiplexing, interrupt handling, device drivers
synchronization primitives, interprocess communication
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API and SPI:
Applications
API
Extensible
system services
SPI (or HAL)
Portable
Platforms
Windows NT: an example of operating system structure
OS / 2 client
Win 32 client
POSIX client
OS / 2
subsystem
Win 32
subsystem
POSIX
subsystem
User Mode
object
manager
security
reference
monitor
process
manager
local
virtual
procedure
memory
call
manager
kernel with hardware abstraction
hardware platform
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I/O
manager
Executives
Kernel Mode
system service API
Overview of centralized operating systems:
Resource Manager
• Process management
– interprocess communication
– process synchronization
– process scheduling
• Memory management
– memory allocation and deallocation
– logical to physical address mapping
– virtual memory support: segmentation and paging
– protection
• Device management
– device driver
– buffering
– spooling
• Data management
– file access
– file sharing
– concurrency control
– data replication
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Process management
• interprocess communication
• process synchronization
• process scheduling
Process States:
Starting
Halting
Initialize PCB
Halt/ABEND
Dispatch/Context switch
Ready
Running
TRO/Context switch
Block
Unblock
Blocked
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Memory management
• memory allocation and deallocation
• logical to physical address mapping
• virtual memory support: segmentation and paging
• protection
Paged Memory:
Logical Address
Page Number
Physical Address
Offset
Page Frame
Page Table
Page Frame
...
...
Control Bits
...
...
V D S
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Offset
Device management
• device driver
• buffering
• spooling
Device Drivers and DMA:
Hardware Independent Interface
Generic Driver Code
Hardware Dependent Code
Physical Device Interface
CPU
RAM
System Bus
DMA
Device 1
...
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Device N
Data management
• file access
• file sharing
• concurrency control
• data replication
Memory Management Unit:
CPU
TLB
MMU
Cache
System Bus
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RAM
Unix File System:
Disk Blocks
Directory
i−node
...
my_file.txt 0x001af38...
...
File Name i−node number
Owner UID
Owner GID
...
...
RC
i−node Table
drwxrwxrwx
...
Direct Blk 0
1−IB 1
Direct Blk 522
Secondary IB
1−IB 2
Direct Blk 523
...
Primary IB 0
1−IB 512
10
...
Direct Blk 521
...
...
Direct Blk 1
...
...
Direct Blk 11
...
...
Direct Blk 10
Unix File Tables:
Proc Ctl Blk
Sys File Tbl
i−node Table
...
...
...
FID
11
...
rc loc mode i−node #
...
PFT ptr
Proc File Tbl
...
...
PID
Network operating system
• interoperability: ability of information exchange among heterogeneous
systems
• supported by network communication protocols
• transport service: the primary interface between operating system and
computer network
• characterized by common network applications (servers)
– remote login
– file transfer
– messaging
– browsing
– remote execution
A network file system example
application processes
file service
network
local
file system
file system
peer
communication
protocols
file service
local
network
file system
file system
device
transport
management
service
device
network
service KERNEL drivers
transport
device
management
service
network
device
drivers KERNEL service
local hardware
application processes
communication network
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local hardware
Distributed operating system
• transparency
• servers for supporting resource sharing and distributed processing
• algorithms to implement transparencies
• details in latter chapters
Service Decomposition vs. Integration
Services
Decomposition in
Integration in
distributed systems
autonomous systems
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Cooperative autonomous system
• client/server model
• object model
• software bus (middleware, broker, or trader)
• CORBA and ODP
• Peer-to-Peer (P2P) systems
• Service Oriented Architecture (SOA) systems
An example of cooperative autonomous system
Yellow Pages
communication
servers
channels
real estate agency
realtor
client
buyer
realtor
well−known server
newspaper
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client
seller
Service Oriented Architecture (SOA)
(from http://en.wikipedia.org/wiki/Service-oriented architecture)
Guiding Principles
• Reuse, granularity, modularity, composability, componentization, interoperability
• Standards compliance
• Service identification and categorization, provisioning and delivery, monitoring and tracking
SOA Elements
General idea of usage is to ”orchestrate” services to develop application.
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Specific SOA Architectural Principles
• Service encapsulation - minimal interface
• Service loose coupling - minimize dependencies
• Service contract - documented specification and agreement
• Service abstraction - internals hidden
• Service reusability - intentional packaging of multi-use services
• Service composability - composite services formed from building blocks
• Service autonomy - owners control logic encapsulated by services offered
• Service optimization - clients can ”shop” for the ”best” service
• Service discoverability - meaningful descriptions available through discovery mechanisms
• Service relevance - granularity is right for meaningful service
Why do we need distributed control algorithms?
An algorithm is sometimes called protocol if it specifies coordination more
than computation.
• algorithm changes due to message passing
• need for consensus algorithms due to lack of global information
• concurrency control algorithms to avoid interference in resource sharing
• coherency control algorithms to maintain consistency for data replication
• protocols for group communication in distributed applications
• fault-tolerance algorithms for handling failure and recovery
• real-time and distributed scheduling algorithms
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