From 583fc1fa5a3612f3ab73bf19b93df23bd9fa1a64 Mon Sep 17 00:00:00 2001 From: Ian Moffett Date: Fri, 26 Apr 2024 14:29:07 -0400 Subject: kernel: sched: Add support for early preemption Signed-off-by: Ian Moffett --- sys/kern/kern_sched.c | 26 +++++++++++++++++++++----- 1 file changed, 21 insertions(+), 5 deletions(-) (limited to 'sys/kern') diff --git a/sys/kern/kern_sched.c b/sys/kern/kern_sched.c index 79480ec..1f302d9 100644 --- a/sys/kern/kern_sched.c +++ b/sys/kern/kern_sched.c @@ -78,16 +78,22 @@ static size_t nthread = 0; */ static struct spinlock tdq_lock = {0}; +/* + * Perform timer oneshot + * + * @now: True for shortest timeslice. + */ static inline void -sched_oneshot(void) +sched_oneshot(bool now) { struct timer timer; + size_t usec = (now) ? SHORT_TIMESLICE_USEC : DEFAULT_TIMESLICE_USEC; tmrr_status_t tmr_status; tmr_status = req_timer(TIMER_SCHED, &timer); __assert(tmr_status == TMRR_SUCCESS); - timer.oneshot_us(DEFAULT_TIMESLICE_USEC); + timer.oneshot_us(usec); } /* @@ -144,7 +150,7 @@ sched_idle(void) __noreturn static void sched_enter(void) { - sched_oneshot(); + sched_oneshot(false); sched_idle(); __builtin_unreachable(); } @@ -354,6 +360,16 @@ sched_make_idletd(void) sched_enqueue_td(td); } +/* + * Cause an early preemption and lets + * the next thread run. + */ +void +sched_rest(void) +{ + sched_oneshot(true); +} + void sched_exit(void) { @@ -406,7 +422,7 @@ sched_context_switch(struct trapframe *tf) * preempt at all. */ if (nthread == 0 || (next_td = sched_dequeue_td()) == NULL) { - sched_oneshot(); + sched_oneshot(false); return; } @@ -436,7 +452,7 @@ sched_context_switch(struct trapframe *tf) /* Done, switch out our vas and oneshot */ pmap_switch_vas(vm_get_ctx(), next_td->addrsp); - sched_oneshot(); + sched_oneshot(false); } void -- cgit v1.2.3