Operating System MCQs

The segment-table entry defines where a segment begins in physical memory and how large it is.
These values support translation and bounds checking.

Most translations complete quickly when the TLB contains the requested entries.
Frequent misses require extra page-table accesses and increase average translation cost.

Associative lookup searches by content rather than by a conventional numeric array index.
Parallel comparison allows rapid translation matching.

Multilevel page tables avoid allocating one enormous flat table for every possible virtual page.
Unused address-space ranges need no lower-level table.

A hashed page table maps virtual page numbers into hash buckets containing translation entries.
It can represent sparse, very large virtual address spaces efficiently.

An inverted table reduces page-table memory by representing physical frames globally.
Entries typically include the owning process and virtual page information.

An address-space identifier tags cached translations with their owning process or address space.
This can avoid flushing the entire TLB on every context switch.

A page-table update may leave cached copies of the old translation on several CPUs.
The system sends coordination requests so those entries are invalidated consistently.

A process size is rarely an exact multiple of the page size.
The remaining bytes in its final frame are allocated but unused.

The valid-invalid mechanism lets hardware reject references outside the process's permitted pages.
In virtual-memory systems, related state can also indicate whether a legal page is resident.

Protection bits specify allowed operations such as read, write, or execute for a page.
The MMU checks these permissions during memory access.

Reentrant read-only code can be safely mapped to the same physical frames for many processes.
Each process may still maintain private writable data pages.