How do interrupts in multicore/multicpu machines work?

Question

I recently started diving into low level OS programming. I am (very slowly) currently working through two older books, XINU and Build Your Own 32 Bit OS, as well as some res

Answer 1

In the old days the interrupt went to all processors. In modern times some kinds of hardware can be programmed by an OS to send an interrupt to one particular processor. Of course if you could choose a processor dynamically instead of statically, you wouldn't want to send the interrupt to whichever processor initiated the I/O, you'd want to send it to whichever processor is least burdened at the present time and can most efficiently start the next I/O operation, and/or whichever processor is least burdened at the present time and can most efficiently execute the thread that was waiting for the results.