Performance Overhead

What is a Context Switch?

A context switch is the process of saving the CPU state of a currently running task and loading the saved state of another task, so a single CPU core can appea…

What is Thrashing in Operating Systems?

Thrashing is a state where a system spends most of its time swapping pages between RAM and disk rather than executing actual instructions, causing CPU utilizat…

What is Busy Waiting and Why is it Costly?

Busy waiting is when a thread repeatedly checks a condition in a tight loop instead of yielding the CPU or being put to sleep, which wastes CPU cycles and star…

What is a Thread Pool and Why Use One?

A thread pool is a fixed or bounded group of pre-created worker threads that pull tasks from a shared queue, so an application avoids the cost of spawning and…

What Causes Context Switch Overhead and How Is It Reduced?

Context switch overhead comes from the direct cost of saving and restoring CPU state plus the indirect cost of losing cache, TLB, and pipeline warmth, and it i…

Polling vs Interrupt-Driven I/O: What Is the Difference?

Polling is where the CPU repeatedly checks a device’s status register in a loop until it is ready, while interrupt-driven I/O lets the CPU do other work and re…

What is Dispatcher Latency?

Dispatcher latency is the time the OS dispatcher takes to stop one process and start another once the scheduler has decided which task should run next — it cov…

What is the Memory Hierarchy in a Computer System?

The memory hierarchy is a layered arrangement of storage technologies — registers, cache, main memory, and secondary storage — ordered by decreasing speed and…