Recap: The OS Abstraction - Bowdoin Collegesbarker/teaching/courses/... · L1)Cache L2)Cache RAM Disk 1"cycle'latency 2"cycle'latency 7"cycle'latency 100'cycle'latency 40,000,000'cycle'latency'

Sean Barker

Recap: The OS Abstraction

1

User-level Applications

Operating System

Hardware

virtual(machine(((interface

physical(machine(((interface

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OS Resource Management

2

Memory

I/O

Processor Processes, scheduling, synchronization

Allocation, protection, virtual memory

Disk management, filesystems, networking

Hardware OS Services

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Today: OS and Computer Architecture

3

networkcard

System bus

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Computer Architecture

4

Logic board

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Assembly Language

5

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Protection: User and Kernel Mode

6

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System Calls

7

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Traps

8

0: 0x00080000

1: 0x00100000

2: 0x00100480

3: 0x00123010

Illegal address

Memory violation

Division by zero

System call

Trap Vector

...

Memory Addresses

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I/O Control & Interrupts

9

0: 0x2ff080000

1: 0x2ff100000

2: 0x2ff100480

3: 0x2ff123010

keyboard

mouse

timer

disk 1

Interrupt Vector

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Synchronous & Asynchronous I/O

10

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Hardware Timer

11

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Memory Protection

12

Base register value

Limit register value

Mem

ory

(byt

es 0

to N

)

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Caches in the Memory Hierarchy

13

registers

L1)Cache

L2)Cache

RAM

Disk

1"cycle'latency

2"cycle'latency

7"cycle'latency

100'cycle'latency

40,000,000'cycle'latency'

Network 200,000,000+'cycle'latency'

load

evict

fast

ersl

ower

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Summary of Architecture Support

14

OS Service Hardware Support

Protection Kernel/user mode, protected instructions, base/limit registers

Interrupts Interrupt vectors

System calls Traps and trap vectors

I/O InterruptsScheduling, error recovery,

accounting Timer

Synchronization Atomic instructions

Virtual memory Translation look-aside buffers