Timed on a PSP, each way of handing the CPU to another thread (the call
and the switch together):
hardware before now
rotate to an equal thread 7 14 7
signal, better thread runs 10 17 10
it waits again, back to caller 10 19 12
wakeup, better thread runs 8 13 6
it sleeps again, back to caller 7 12 6
start a better thread, entry 30 28 30
thread ends, back to its waiter 21 13 20
notify, better thread's callback 14 13 14
A switch between two threads now costs 1150 cycles instead of 2700.
Starting a better thread costs 2000 cycles more, ending a thread 3300,
and setting up a callback 1800.
Also splits a wait timeout's ~30us into the deadline being taken 12us
into the call and the timeout going off 18us after it. That only changes
the time left written back, which threads/semaphores/wait and
threads/fpl/cancel pin between them. intr/vblank is re-recorded so it
no longer depends on the phase of the frame.
threads/callbacks/combos now passes.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
