3 ms·

Any interrupt will take the processor out of hlt state; i.e. hit a key on the keyboard, it will fire an interrupt and the processor will start processing again.

Any interrupt will take the processor out of hlt state; i.e. hit a key on the keyboard, it will fire an interrupt and the processor will start processing again. The clock tick will also fire an interrupt. Once it fires an interrupt it will start searching for runnable processes again; e.g. a process can now return from a read() from it's STDIN tty now that you have typed a key.

swetland 13y ago
There's some inefficiency here in that wake() doesn't cause the other cpu to wake immediately from hlt so it'll remain halted until the next timer tick or whatnot. It'd be fun to add some scheduler stats and poke around with things a bit. Some really trivial cprintf() tracing in scheduler() implies that single processes can ping-pong between CPUs, but the printing itself is slow and invasive and could possibly be the cause.