500-4 Yhtomit
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Week4OperatingSystems-V2016.pptWeek 4
Operating Systems
Card
Punch - verify - sort - process - print - archive
Batch – static – rigid - time intensive - manual – automate sequential vs random
memory constraints
Smart IO, CU, width
CU – offload work – CPU -GPU
Benchmark – Clock Speed – Overclocking
Bigger is better – more instructions – memory – colors – IO devices – IP addresses – yada yada -
Mono Processing - Program application owns all HW resources
OpCode ---- Operand (parameters)
Von Neumann – function – structure
Week 4
- Program set of instructions
- Process / task program in execution
- Each process has it’s own address space
- Consisting of instruction region
- Data region
- Stack region
- Process run for an interval or quantum of time
Uni-programming
- Difficult application development
- Assembler or machine language
- No error recovery
- Job scheduling (batch processing)
- Processor had to do all operations
- Inefficient use of resources
- Non real-time
Operating System
- Definition “software that controls hardware”
- Resource manager - Gatekeeper
- Interface between user and hardware
- Separates application from hardware
- File manager
- Kernel is the core component of the OS
OS
Single-user, dedicated machine
User program
Unused
Memory
OS Objectives and Functions
- Convenience
- Making the computer easier to use
- Efficiency
- Allowing better use of computer resources
- Simplicity
- Application developers can use system procedures to reduce code
*
Multiprogramming
- Carve memory into partitions
- Unique app’s loaded into each partition
- Operating system switches HW resources between partitions for a quantum of time
- Appears to run simultaneously
- Efficient use of processor resources
- Real-time data
- Con = overhead, complex
Partition 1
Partition 2
Partition 3
Operating System
Hardware
Time a
Time b
Time c
Application a
Application b
Application c
M
E
M
O
R
Y
M
E
M
O
R
Y
Process states
- Running
- Ready
- Blocked
- Wait
- Suspended
Scheduling Algorithms
- First-In-First-Out FIFO
- Round-Robin RR
- Shortest-Process-First SPF
- Shortest-Remaining-Time SRT
- Multilevel Feedback Queue
- Fair Share Scheduling
FIFO
CPU
A
B
C
Completion
Job Queue
A
Preemption
RR
Process control block
- PID- Process identification number
- PC- Program counter
- Registers
- State
- Priority
- Address space
- Flags / etc
Multitasking
Layers and Views of a Computer System
*
Operating System Services
- Program creation
- Program execution
- Access to I/O devices
- Controlled access to files
- System access
- Error detection and response
- Accounting
*
O/S as a Resource Manager
*
Memory management
- Fixed size partitioning
- Variable-size partitioning
- Fragmentation
- Memory leak
Fixed size partitioning
Variable-size partitioning
Issues with address space - Fragmentation
Memory Leak
4K Page Segment
4K Page Segment
4K Page Segment
4K Page Segment
Disk
Memory
Free
Virtual memory
LPAR
$64 Million Question
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What does this have to do with security?
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Break then Board Work
