Operating Systems Chapter 2 review

False

A singleuser system supports multiprogramming.

Null entry

A(n) __​__ in the busy list occurs when a memory block between two other busy memory blocks is returned to the free list. a. blank line c. joined entry b. null entry d. empty entry

Relocation register

In a relocatable dynamic partition scheme, the __​__ contains a value that must be added to each address referenced in a program so that the system will be able to access the correct memory addresses after relocation. a. bounds register c. relocation register b. load register d. compaction register

Bounds register

In a relocatable dynamic partition scheme, the __​__ ensures that, during execution, a program won't try to access memory locations that don't belong to it. a. relocation register c. compaction register b. load register d. bounds register

sequentially

In a singleuser system, jobs are processed ___. a. sequentially c. randomly b. intermittently d. in order of longest job to shortest job

First-fit memory allocation

The __​__ method keeps the free/busy lists organized by memory locations, from loworder memory to highorder memory. a. fixed partition allocation c. dynamic fit memory allocation b. firstfit memory allocation d. bestfit memory allocation

True

The algorithm used to store jobs into memory in a fixed partition system requires a few more steps than the one used for a singleuser system because the size of the job must be matched with the size of the partition to make sure it fits completely.

False

The bestfit allocation method keeps the free/busy lists organized by memory locations, loworder memory to highorder memory.

True

The bounds register ​is used to store the highest (or lowest, depending on the specific system) location in memory accessible by each program.

partition size, memory address, access, and status

In the fixedpartition memory management scheme, the table that the Memory Manager uses to keep track of jobs is composed of the ____. ​ a. partition size, memory address, and status b. status, access, and memory address c. partition size, status, and access d. partition size, memory address, access, and status

True

In the relocatable dynamic partitions scheme, the Memory Manager relocates programs to gather together all of the empty blocks and compact them to make one block of memory large enough to accommodate some or all of the jobs waiting to get in.

True

The first attempt to allow for multiprogramming used fixed partitions.

False

The firstfit algorithm assumes that the Memory Manager keeps only one list containing free memory blocks

False

The fixed partition scheme does not require that the entire program be stored contiguously and in memory from the beginning to the end of its execution

True

The fixed partition scheme works well if all of the jobs run on the system are of the same size or if the sizes are known ahead of time and don't vary between reconfigurations.

All jobs are of similar size

The fixed partition scheme works well when ____. a. all jobs are of similar size b. jobs have different sizes c. job sizes are not known in advance d. all jobs are under 100K

Loaded into memory

The four memory management techniques presented in this chapter share the requirement that the entire program being executed must be ____. ​ a. loaded into memory c. written in a single language b. stored on disk d. Relocatable

Best-fit

The goal of the ____ memory allocation algorithm is to find the smallest memory block into which a job will fit. a. smallestfit c. dynamicfit b. firstfit d. bestfit

Function

When reading an instruction, the operating system can tell the __​__ of each group of digits by its location in the line and the operation code. a. function c. order b. value d. assignment

External Fragmentation

__​_ consists of fragments of free memory between blocks of allocated memory. a. An inefficient fit c. External fragmentation b. Indirect partitioning d. Internal fragmentation

Compaction

_​_ of memory is performed by the operating system to reclaim fragmented sections of the memory space. a. Deallocation c. Compaction b. Redirection d. Reallocation

Static

Fixed partitions are also called __ _​ partitions. a. complete c. direct b. static d. sized

False

For a fixed partition system, memory deallocation is relatively complex.

Random Access Memory

Main memory is also known as ___ a. single user memory c. finite memory b. random access memory d. virtual memory

True

Research continues to focus on finding the optimum allocation scheme

True

A large job can have problems with a firstfit memory allocation scheme.

True

After relocation and compaction, both the free list and the busy list are updated.

Overhead

By compacting and relocating, the Memory Manager optimizes the use of memory and thus improves throughput. However, it also requires more __​_ than the other memory allocation schemes discussed in this chapter. a. null entries c. main memory b. segmentation d. overhead

False

Compaction should always be performed only when there are jobs waiting to get in

True

In a dynamic partition system, a null entry in the busy list occurs when a memory block between two other busy memory blocks is returned to the free list.

True

In a fixed partition scheme, large jobs will need to wait if the large partitions are already booked, and they will be rejected if they're too big to fit into the largest partition

Defregmentation

Memory compaction is also referred to as __​__. a. defragmentation c. reallocation b. collection d. dynamic allocation

percentage

One approach to performing compaction is to do it when a certain __​__ of memory becomes busy. a. byte c. bit b. percentage d. area

True

One of the problems with the bestfit algorithm is that the entire table must be searched before the allocation can be made because the memory blocks are physically stored in sequence according to their location in memory.

True

Singleuser contiguous allocation schemes have the problem of partition intrusion.

True

Singleuser systems in a nonnetworked environment allocate, to each user, access to all available main memory for each job, and jobs are processed sequentially, one after the other

Relocatable Dynamic Partitions

Singleuser, fixed partition, and dynamic partition memory schemes share unacceptable fragmentation characteristics that were resolved with the development of ____. a. deallocation c. relocatable dynamic partitions b. bestfit algorithms d. null entry accounting

Internal Fragmentation

The phenomenon of lessthancomplete use of memory space in a fixed partition is called ____. a. dynamic fragmentation c. external fragmentation b. internal fragmentation d. fixed fragmentation

Fragmentation

The release of memory space by the Memory Manager is called __​__. a. fragmentation c. free memory b. relocation d. deallocation