Operating System MCQs

Shared-cache topology can either help communicating threads or create contention among unrelated workloads.
A topology-aware scheduler considers both effects when placing threads.

Processor affinity favors running a thread on a previous CPU to preserve cache locality.
Avoiding unnecessary migration can improve performance on multiprocessor systems.

Concurrency can be achieved by interleaving tasks on one processor or by simultaneous execution.
Parallelism specifically requires overlapping execution on multiple processing units.

Data parallelism divides a common data set into parts processed by similar operations concurrently.
Task parallelism instead assigns different kinds of work to different threads.

Asymmetric multiprocessing assigns a master processor to handle scheduling and selected kernel responsibilities.
Other processors execute tasks directed by the master.

Thread-local storage gives each thread its own instance of a logically common variable.
It is useful for per-thread state that should not be shared or locked.

Scheduler activations provide a communication mechanism between the kernel and a user-level thread library.
They help the library react when kernel threads block, resume, or become available.

A lightweight process acts as an intermediate kernel scheduling resource for user-level threads.
The user thread library multiplexes its threads over these entities.

Process-contention scope selects among user threads belonging to one process.
The thread library typically performs this competition before the kernel schedules underlying entities.

System-contention scope schedules kernel-visible threads against other runnable threads system-wide.
This is the normal scope for kernel-level thread scheduling.

POSIX fork semantics normally replicate only the thread that invoked fork into the child process.
This creates synchronization concerns because locks held by vanished sibling threads may remain copied.

exec replaces the entire process address space with a new program image.
Only the new program's initial execution context remains after the replacement.