CVSROOT: /cvs
Module name: src
Changes by: chel...@cvs.openbsd.org 2023/08/05 14:07:56
Modified files:
sys/kern : kern_clock.c kern_time.c kern_clockintr.c
kern_sched.c sched_bsd.c
sys/sys : time.h sched.h proc.h systm.h
Log message:
hardclock(9): move setitimer(2) code into itimer_update()
- Move the setitimer(2) code responsible for updating the ITIMER_VIRTUAL
and ITIMER_PROF timers from hardclock(9) into a new clock interrupt
routine, itimer_update(). itimer_update() is periodic and runs at the
same frequency as the hardclock.
+ Revise itimerdecr() to run within itimer_mtx instead of entering
and leaving it.
- Each schedstate_percpu has its own itimer_update() handle, spc_itimer.
A new scheduler flag, SPCF_ITIMER, indicates whether spc_itimer was
started during the last mi_switch() and needs to be stopped during the
next mi_switch() or sched_exit().
- A new per-process flag, PS_ITIMER, indicates whether ITIMER_VIRTUAL
and/or ITIMER_PROF are running. Checking the flag is easier than
entering itimer_mtx to check process.ps_timer[]. The flag is set
and cleared in a new helper function, process_reset_itimer_flag().
- In setitimer(), call need_resched() when the state of ITIMER_VIRTUAL
or ITIMER_PROF is changed to force an mi_switch() and update
spc_itimer.
claudio@ notes that ITIMER_PROF could be implemented as a high-res
timer using the thread's execution time as a guide for when to
interrupt the process and assert SIGPROF. This would probably work
really well in single-threaded processes. ITIMER_VIRTUAL would be
more difficult to make high-res, though, as you need to exclude time
spent in the kernel.
Tested on powerpc64 by gkoehler@. With input from claudio@.
Thread: https://marc.info/?l=openbsd-tech&m=169038818517101&w=2
ok claudio@
