External fragmentation will not occur when :
Answer: D
Correct answer: no matter which algorithm is used, it will always occur
Every contiguous allocation scheme leaves gaps as processes of different sizes come and go, so the placement strategy affects how much external fragmentation occurs but cannot prevent it. Only non-contiguous allocation removes the problem.
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Sometimes the overhead of keeping track of a hole might be :
Answer: B
Correct answer: larger than the hole itself
A hole must be recorded in the free list, and if the hole is very small the record costs more memory than the hole would ever supply. Such holes are therefore left attached to the allocated block, which converts external fragmentation into internal.
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When the memory allocated to a process is slightly larger than the process, then :
Answer: A
Correct answer: internal fragmentation occurs
Memory allocated to a process but not used by it is internal fragmentation - the waste lies inside the allocation. External fragmentation is waste between allocations.
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Physical memory is broken into fixed-sized blocks called ________
Answer: A
Correct answer: frames
Physical memory is divided into fixed-size frames and logical memory into pages of the same size. Keeping the two names apart is what makes the rest of paging describable.
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Logical memory is broken into blocks of the same size called _________
Answer: B
Correct answer: pages
Logical memory is divided into pages, which are the same size as the physical frames they are loaded into.
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Every address generated by the CPU is divided into two parts :
Answer: B
Correct answer: page number & page offset
A logical address splits into a page number, which selects an entry in the page table, and a page offset, which is carried through unchanged to index within the frame.
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The __________ is used as an index into the page table.
Answer: B
Correct answer: page number
The page number indexes the page table; the entry found there gives the frame number, which replaces it to form the physical address.
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The _____ table contains the base address of each page in physical memory.
Answer: C
Correct answer: page
The page table holds one entry per page, giving the base address in physical memory of the frame that page occupies.
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The size of a page is typically :
Answer: B
Correct answer: power of 2
Page size is a power of two so that the split of an address into page number and offset requires no division: the low bits are the offset and the high bits the page number.
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If the size of logical address space is 2 to the power of m, and a page size is 2 to the power of n addressing units, then the high order _____ bits of a logical address designate the page number, and the ____ low order bits designate the page offset.
Answer: D
Correct answer: m – n, n
If the address is m bits and the page size is \( 2^{n} \), the low n bits are the offset within the page and the remaining m − n bits are the page number.
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