Memory Management Flashcards
Which of the following is a benefit of allowing a program that is only partially in memory to
execute?
A) Programs can be written to use more memory than is available in physical memory.
B) CPU utilization and throughput is increased.
C) Less I/O is needed to load or swap each user program into memory.
D) All of the above
D- ALL OF THE ABOVE
In systems that support virtual memory, ____.
A) virtual memory is separated from logical memory.
B) virtual memory is separated from physical memory.
C) physical memory is separated from secondary storage.
D) physical memory is separated from logical memory
D- PHYSICAL MEMORY IS SEPARATED FROM LOGICAL MEMORY
The vfork() system call in UNIX ____.
A) allows the child process to use the address space of the parent
B) uses copy-on-write with the fork() call
C) is not intended to be used when the child process calls exec() immediately after creation
D) duplicates all pages that are modified by the child process
A- ALLOWS THE CHILD PROCESS TO USE THE ADDRESS SPACE OF THE PARENT
Belady’s anomaly states that ____.
A) giving more memory to a process will improve its performance
B) as the number of allocated frames increases, the page-fault rate may decrease for all page
replacement algorithms
C) for some page replacement algorithms, the page-fault rate may decrease as the number of
allocated frames increases
D) for some page replacement algorithms, the page-fault rate may increase as the number of
allocated frames increases
D- FOR SOME PAGE REPLACEMENT ALGORITHMS, THE PAGE-FAULT RATE MAY INCREASE AS THE NUMBER OF ALLOCATED FRAMES INCREASES
Optimal page replacement ____.
A) is the page-replacement algorithm most often implemented
B) is used mostly for comparison with other page-replacement schemes
C) can suffer from Belady’s anomaly
D) requires that the system keep track of previously used pages
B- IS USED MOSTLY FOR COMPARISON WITH OTHER PAGE-REPLACEMENT SCHEMES
The _____ allocation algorithm allocates available memory to each process according to its size.
A) equal
B) global
C) proportional
D) slab
C- PROPORTIONAL
The \_\_\_\_ is the number of entries in the TLB multiplied by the page size. A) TLB cache B) page resolution C) TLB reach D) hit ratio
C- TLB REACH
________ allows the parent and child processes to initially share the same pages, but when either process modifies a page, a copy of the shared page is created.
A) copy-on-write
B) zero-fill-on-demand
C) memory-mapped
D) virtual memory fork
A- COPY-ON-WRITE
_____ is the algorithm implemented on most systems. (for page fault)
A) FIFO
B) Least frequently used
C) Most frequently used
D) LRU
~~~
D- LRU
LRU stands for Least Recently Used. As the name suggests, this algorithm is based on the strategy that whenever a page fault occurs, the least recently used page will be replaced with a new page
. \_\_\_\_\_ occurs when a process spends more time paging than executing. A) Thrashing B) Memory-mapping C) Demand paging D) Swapping
A- THRASHING
Windows uses a local page replacement policy _____.
A) when a process exceeds its working set minimum
B) when a process exceeds its working set maximum
C) when the system undergoes automatic working set trimming
D) under all circumstances
B- WHEN A PROCESS EXCEEDS ITS WORKING SET MAXIMUM
Explanation for C:
When a system undergoes automatic working set trimming, it means that the operating system or a memory management component dynamically adjusts the working set of a process to optimize memory usage and system performance.
The working set of a process refers to the subset of its pages that are actively used to access during a specific time period. It represents the set of pages that the process requires to execute efficiently without incurring excessive page faults.
Which of the following statements is false with regard to Solaris memory management?
A) The speed at which pages are examined (the scanrate) is constant.
B) The pageout process only runs if the number of free pages is less than lotsfree.
C) An LRU approximation algorithm is employed.
D) Pages selected for replacement may be reclaimed before being placed on the free list.
A- THE SPEED AT WHICH PAGES ARE EXAMINED (THE SCANRATE) IS CONSTANT
Which of the following statements is false with regard to allocating kernel memory?
A) Slab allocation does not suffer from fragmentation.
B) Adjacent segments can be combined into one larger segment with the buddy system.
C) Because the kernel requests memory of varying sizes, some of which may be quite small, the system does not have to be concerned about wasting memory
C
The _____ is an approximation of a program’s locality.
A) locality model
B) working set
C) page fault frequency
D) page replacement algorithm
B- WORKING SET
Working set: set of actively used resources or data elements in a program or system at a given point in time.
Program locality refers to the tendency of a program to access certain data or instructions more frequently or in a clustered manner
\_\_\_\_\_\_ allows a portion of a virtual address space to be logically associated with a file. A) Memory-mapping B) Shared memory C) Slab allocation D) Locality of reference
A- MEMORY MAPPING