What Actually Happens During a Linux Context Switch: Registers, TLB Flushes, and the True Cost of Multithreading

Every backend engineer learns early on that threads are not free. We are told to keep thread pools bounded, avoid context-switch storms, and prefer event loops or green threads for high concurrency. Yet if you ask a developer what a context switch actually costs, the answer is usually vague: "It takes a microsecond or two to save some registers."... Weiterlesen