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kernel: disable hardclock() on secondary CPUs
> Date: Mon, 12 Feb 2024 11:35:20 -0600
> From: Scott Cheloha <scottcheloha@gmail.com>
>
> On Fri, Feb 09, 2024 at 11:57:00AM -0600, Scott Cheloha wrote:
> > Now that the dt(4) probe entry points are out of the hardclock() we
> > can disable it on secondary CPUs. There is no useful work left for
> > them to do there.
> >
> > This can wait a few days, just in case we need to back out the dt(4)
> > change.
> >
> > Thoughts?
>
> Ping.
ok kettenis@
Does this mean that we'll start running less interrupts on secondary
CPUs now?
> Index: kern_clockintr.c
> ===================================================================
> RCS file: /cvs/src/sys/kern/kern_clockintr.c,v
> diff -u -p -r1.66 kern_clockintr.c
> --- kern_clockintr.c 9 Feb 2024 16:52:58 -0000 1.66
> +++ kern_clockintr.c 12 Feb 2024 17:35:03 -0000
> @@ -63,7 +63,7 @@ clockintr_cpu_init(const struct intrcloc
> clockqueue_intrclock_install(cq, ic);
>
> /* TODO: Remove this from struct clockintr_queue. */
> - if (cq->cq_hardclock.cl_expiration == 0) {
> + if (CPU_IS_PRIMARY(ci) && cq->cq_hardclock.cl_expiration == 0) {
> clockintr_bind(&cq->cq_hardclock, ci, clockintr_hardclock,
> NULL);
> }
> @@ -99,12 +99,6 @@ clockintr_cpu_init(const struct intrcloc
> clockintr_schedule(&cq->cq_hardclock, 0);
> else
> clockintr_advance(&cq->cq_hardclock, hardclock_period);
> - } else {
> - if (cq->cq_hardclock.cl_expiration == 0) {
> - clockintr_stagger(&cq->cq_hardclock, hardclock_period,
> - multiplier, MAXCPUS);
> - }
> - clockintr_advance(&cq->cq_hardclock, hardclock_period);
> }
>
> /*
> Index: kern_clock.c
> ===================================================================
> RCS file: /cvs/src/sys/kern/kern_clock.c,v
> diff -u -p -r1.122 kern_clock.c
> --- kern_clock.c 9 Feb 2024 17:42:18 -0000 1.122
> +++ kern_clock.c 12 Feb 2024 17:35:03 -0000
> @@ -140,13 +140,6 @@ initclocks(void)
> void
> hardclock(struct clockframe *frame)
> {
> - /*
> - * If we are not the primary CPU, we're not allowed to do
> - * any more work.
> - */
> - if (CPU_IS_PRIMARY(curcpu()) == 0)
> - return;
> -
> tc_ticktock();
> ticks++;
> jiffies++;
>
>
kernel: disable hardclock() on secondary CPUs