4 ms·

> It takes more than one clock cycle to determine the next task that we're going to resume execution for and then actually resume it. Not really, if you just i

• wahern 8y ago
  The difference between stackful coroutines (i.e. fibers in this case) and Python-style coroutines is that Python's coroutines need to rebuild the stack on every resume, whereas resuming a fiber is basically a goto. The cost of yielding and resuming a coroutine in Python is O(N) for the depth of the call chain, but O(1) for fibers. So as you say, a simple scheduler that just walks a linked-list could resume a stackful coroutine in a few instructions, plus the cost of restoring hardware registers (which is the same cost as a non-inlined function call), and the latter is easily pipelined so would take fewer cycles than instructions.
  • tomp 8y ago
    Indeed, a highly-optimized scheduler is basically the same as looping through an array and calling virtual methods of each object. Extremely cheap.