13- The Abstraction: Address Space

Memory virtualization

OS virtualizes its physical memory

Memory virtualization

OS provides an illusion memory space per process

Memory virtualization

it seems to be seen like each process uses the whole memory

Time and Space

benefit of memory virtualization, memory efficiency in terms of _ _ _

Errant Accesses

benefit of memory virtualization, the guarantee of isolation for processes as well as OS, protection from _ _ of other processes

Library

OS in early systems, OS is just a _

Only One Process

OS in early systems, load _ _ _ in memory

Executes until completion

load only one process in memory (1)

Poor CPU utilization and memory efficiency

load only one process in memory (2)

Increase CPU utilization and memory efficiency

result of load multiple processes in memory

Batch processing

systems became more interactive compared to doing just _ _

Protection issue

load multiple processes, introduces an important _ _

Abstraction

the address space/mapping contains information all about running process

Memory state

a running program’s (process) own view of memory

Code

where instruction live

Heap

dynamically allocate memory

Stack

stores return address during function calls or return values

Stack

contains local variables, actual parameters to function

Transparency

implementation should be invisible to a process

Transparency

process behaves as if its has its own private physical memory

Efficiency

in terms of time (not make processes run slowly) and space (not much overhead in memory use)

Efficiency

will need to rely on hardware support (TLBs, etc)

Protection and Isolation

prevent a user protection from accessing other user processes, or the kernel