void xnclock_core_local_shot(struct xnsched *sched)
{
struct xntimerdata *tmd;
struct xntimer *timer;
xnsticks_t delay;
xntimerh_t *h;
/*
* Do not reprogram locally when inside the tick handler -
* will be done on exit anyway. Also exit if there is no
* pending timer.
*/
if (sched->status & XNINTCK)
return;
tmd = xnclock_this_timerdata(&nkclock);
h = xntimerq_head(&tmd->q);
if (h == NULL)
return;
/*
* Here we try to defer the host tick heading the timer queue,
* so that it does not preempt a real-time activity uselessly,
* in two cases:
*
* 1) a rescheduling is pending for the current CPU. We may
* assume that a real-time thread is about to resume, so we
* want to move the host tick out of the way until the host
* kernel resumes, unless there is no other outstanding
* timers.
*
* 2) the current thread is running in primary mode, in which
* case we may also defer the host tick until the host kernel
* resumes.
*
* The host tick deferral is cleared whenever Xenomai is about
* to yield control to the host kernel (see ___xnsched_run()),
* or a timer with an earlier timeout date is scheduled,
* whichever comes first.
*/
sched->lflags &= ~XNHDEFER;
timer = container_of(h, struct xntimer, aplink);
if (unlikely(timer == &sched->htimer)) {
if (xnsched_resched_p(sched) ||
!xnthread_test_state(sched->curr, XNROOT)) {
h = xntimerq_second(&tmd->q);
if (h) {
sched->lflags |= XNHDEFER;
timer = container_of(h, struct xntimer, aplink);
}
}
}
int xntimer_heading_p(struct xntimer *timer)
{
struct xnsched *sched = timer->sched;
xntimerq_t *q;
xntimerh_t *h;
q = xntimer_percpu_queue(timer);
h = xntimerq_head(q);
if (h == &timer->aplink)
return 1;
if (sched->lflags & XNHDEFER) {
h = xntimerq_second(q);
if (h == &timer->aplink)
return 1;
}
return 0;
}
