Module 3 Flashcards
How an operating system handles primary memory and moves processes between main memory and disk during execution.
Memory Management
Process of mapping from one address space to another.
Address Binding
A process is moved between ___ and ___ during its execution.
disk, memory
Collection of processes that are waiting to be brought into memory
Job Queue or Input Queue
Address Binding where the location of a process is known at compile time
Compile Time Address Binding
Address Binding where the location of a process is not known at compile time
Load Time Address Binding
Translates the relocatable address to absolute address
Loader
Added to the logical address to gain the physical address
Base Address
Address Binding where the instructions are now in memory and being processed
Execution Time Address Binding
Method that helps OS collect and merge various modules of code and data into a single executable file
Linking
The operating system can link system-level libraries in a program that combines them at ___
Load Time
Linking that is done during load or run time
Dynamic Linking
Used to obtain better memory-space utilization.
Dynamic Loading
A ____ is not loaded until it is called and kept on disk in a relocatable load format.
routine
Whenever a routine is called, the ________ is called to load the routine into memory and update the program’s address tables.
relocatable linking loader
Address generated by the CPU.
Logical Address
An address seen by the memory unit.
Physical Address
In these address binding, logical and physical addresses are the same.
Compile-Time and Load-Time
In this address binding scheme, the logical and physical addresses are different.
Execution-Time
The run-time mapping from logical to physical is done by the ___
Memory Management Unit
The base register can be substituted for the ____
relocation register
Process of reserving a portion of computer memory for the execution of programs and processes.
Memory Allocation
The Operating System is partitioned to the ___
Low Memory
The user processes is partitioned to the ___
High Memory
Memory Allocation technique that doesn’t support multiprogramming
Single Partition
Oldest technique to put more than one process in the main memory.
Multiple Fixed Partitions
In this partitioning, the number of partitions (non-overlapping) in RAM is fixed but the size of each partition may or may not be the same.
Multiple Fixed Partitions
In fixed partitions, each partition can only contain ____ process.
One
The degree of multiprogramming is bounded by the ____?
Number of Partitions
Assigns the first process to the first available partition
First-fit allocation
Looks for the process that fits the best in the partition.
Best-fit allocation
In this allocation, jobs with a size closest to a partition is assigned to that partition
Best-fit allocation
Happens when free memory is broken into little pieces.
Fragmentation
It happens after processes cannot be allocated to memory blocks considering their small size and memory blocks remains unused.
Fragmentation
____ occurs when a partition is too big for a process.
Internal fragmentation
____ occurs when a partition is available, but is too small for any waiting job.
External fragmentation
Allocation technique that allows the partition sizes to vary dynamically
Multiple Variable Partitions
Large block of available memory
hole
The Multiple Variable Partitions again follows the ____ in scheduling processes.
FCFS algorithm
Allocate the first hole large enough. This algorithm is generally faster but it tends to exhibit external fragmentation.
First Fit
Allocate the smallest hole large enough. This produces the smallest leftover hole but may leave holes that are too small.
Best Fit
Allocate the largest hole. This algorithm produces the largest leftover hole but tends to scatter the unused portions over non-contiguous areas of memory.
Worst Fit
Process of merging adjacent holes into one larger hole
coalescing
T/F
Internal fragmentation does not exist in MVT
True
Technique that shuffles memory to place all free memory together in one large block.
Compaction
Variation of MVT that uses compaction to minimize external fragmentation.
Multiple Relocatable Variable Partitions (MRVT)
Process that can minimize external fragmentation.
Multiple Relocatable Variable Partitions or Paging
It permits a program’s memory to be non-contiguous allowing the operating system to allocate physical memory whenever possible.
Paging
Memory management technique for controlling how a computer or virtual machine’s memory resources are shared.
Memory paging
Non-physical memory and a section of a hard disk set up to emulate the computer’s RAM.
Virtual Memory
The portion of the hard disk that acts as physical memory
Page File
T/F
The memory frame size is EQUAL to the process page size.
True
The OS translates logical address into physical address in main memory with the use of a ___
Page Table
The OS breaks a processes into ____.
Pages
The OS divides main memory into fixed-sized blocks or ___
frames
T/F
The pages of a process may reside in different frames in main memory.
True
Indicates what page the word resides.
Page Number (p)
Selects the word within the page.
Page Offset (s)
Used as an index into the page table.
Page Number
Contains the base address of each page in physical memory.
Page Table
This base address is combined with the page offset to get the ____
physical address
The page size or frame size is defined by the hardware and is typically a power of ___ between 512 bytes and 16 MB per page.
2
The high-order m – n bits of a logical address designate the ___
page number
the n lower-order bits designate the
page offset
T/F
There is no external fragmentation in paging
True
T/F
It is possible to have internal fragmentation if the memory requirements of a process do not happen to fall on page boundaries.
True
In the worst case, a process would need n pages plus one byte. It would result in an ___ of almost an entire frame.
internal fragmentation
Memory management technique in which each job is divided into several segments of different sizes.
Segmentation (Duh)
T/F
Each segment is a different logical address space of the program.
True
When a process is executed, its segmentation are loaded into ___.
non-contiguous memory
Every segment is loaded into a ___ of available memory.
contiguous block
Segmentation works very similar to paging but segments are of ___
variable-length
In segmentation, a logical address space is a collection of ___.
Segments
The OS maintains a ___ for every process and a list of free memory blocks along with segment numbers, their size and corresponding memory locations.
Segment Map Table
For each segment, the table stores the ____ and ____ of a segment.
Starting address and length
You can get the physical address of a segment by adding a ___ to the base address
reference/offset
If the reference exceeds the physical memory, it results in a ___
Trap
