Revisiting the Cache Interference Costs of Context Switching

The high cost of context switching is one reason that operating system performance is not keeping pace with hardware improvements. Besides the cost of saving and restoring registers, another component of context switch cost is the cache interference between multiple processes sharing the same cache. We measured kernel on user, user on kernel, and user on user cache interference from context switching using a complete machine simulator. While the resulting cache interference is noticeable, the time between process switches is generally sufficient to amortize this cost over a large number of instructions. Completely eliminating all context-switch cache interference would therefore have a minimal impact on total execution time.