List of top Computer Science and IT Engineering Questions on Memory Management and Virtual Memory

Consider contiguous allocation of physical memory to processes using variable
partitioning scheme. Suppose there are 8 holes in the memory of sizes 20 KB, 4 KB,
25 KB, 18 KB, 7 KB, 9 KB, 15 KB, and 12 KB. Assume that no two holes are
adjacent. Two processes P1 of size 16 KB and P2 of size 9 KB arrive in that order,
and they are allocated memory using the best-fit technique. After allocating space
to P1 and P2, the number of holes of size less than 8 KB is ____________. (answer
in integer)
Note: \(1\mathrm{K}=2^{10}\)

A system has a Translation Lookaside Buffer (TLB) that has a reach of 1 MB. TLB
reach is defined as the total amount of physical memory that can be accessed
through the TLB entries. The paging system uses pages of size 4 KB. The virtual
address space is 64 GB and physical address space is 1 GB. If each TLB entry stores
a 4-bit process id, page number, frame number, and a 2-bit control field, then the
size of the TLB (in bytes) is ___________. (answer in integer)
Note: \(1\mathrm{K}=2^{10}\), \(1\mathrm{M}=2^{20}\), \(1\mathrm{G}=2^{30}\)

Consider a system that has a cache memory unit and a memory management unit
(MMU). The address input to the cache memory is a physical address. The MMU
has a translation lookaside buffer (TLB). Assume that when a page is evicted from
the main memory, the corresponding blocks in the cache are marked as invalid.
For a given memory reference, which of the following sequences of events can
NEVER happen?