Socket recv() one byte at a time

Question

Is it a good idea to call recv() one byte at a time with sockets (in terms of performance)? Does it cause a context switch? If so why is there a context switch?

Answer 1

Calling recv() one byte at a time will negatively impact performance. There is a certain amount of overhead on each call -- the transition to kernel mode, file descriptor lookup, dispatch to the protocol-specific driver, buffer/queue locking, etc. Calling recv() with larger buffers greatly decreases the average overhead per byte.