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Commit 3b495b22 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

posix-cpu-timers: Simplify timer queueing 



Now that the expiry cache can be accessed as an array, the per clock
checking can be reduced to just comparing the corresponding array elements.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarFrederic Weisbecker <frederic@kernel.org>
Link: https://lkml.kernel.org/r/20190821192921.212129449@linutronix.de
parent 11b8462f

kernel/time/posix-cpu-timers.c

+21 −34
Original line number Diff line number Diff line
@@ -456,20 +456,20 @@ static inline int expires_gt(u64 expires, u64 new_exp) 
 */

static void arm_timer(struct k_itimer *timer)

{

	struct cpu_timer_list *const nt = &timer->it.cpu;

	int clkidx = CPUCLOCK_WHICH(timer->it_clock);

	u64 *cpuexp, newexp = timer->it.cpu.expires;

	struct task_struct *p = timer->it.cpu.task;

	struct list_head *head, *listpos;

	struct task_cputime *cputime_expires;

	struct cpu_timer_list *const nt = &timer->it.cpu;

	struct cpu_timer_list *next;



	if (CPUCLOCK_PERTHREAD(timer->it_clock)) {

		head = p->posix_cputimers.cpu_timers;

		cputime_expires = &p->posix_cputimers.cputime_expires;

		head = p->posix_cputimers.cpu_timers + clkidx;

		cpuexp = p->posix_cputimers.expiries + clkidx;

	} else {

		head = p->signal->posix_cputimers.cpu_timers;

		cputime_expires = &p->signal->posix_cputimers.cputime_expires;

		head = p->signal->posix_cputimers.cpu_timers + clkidx;

		cpuexp = p->signal->posix_cputimers.expiries + clkidx;

	}

	head += CPUCLOCK_WHICH(timer->it_clock);



	listpos = head;

	list_for_each_entry(next, head, entry) {
@@ -479,8 +479,8 @@ static void arm_timer(struct k_itimer *timer) 
	}

	list_add(&nt->entry, listpos);



	if (listpos == head) {

		u64 exp = nt->expires;

	if (listpos != head)

		return;



	/*

	 * We are the new earliest-expiring POSIX 1.b timer, hence
@@ -488,27 +488,14 @@ static void arm_timer(struct k_itimer *timer) 
	 * for process timers we share expiration cache with itimers

	 * and RLIMIT_CPU and for thread timers with RLIMIT_RTTIME.

	 */

	if (expires_gt(*cpuexp, newexp))

		*cpuexp = newexp;



		switch (CPUCLOCK_WHICH(timer->it_clock)) {

		case CPUCLOCK_PROF:

			if (expires_gt(cputime_expires->prof_exp, exp))

				cputime_expires->prof_exp = exp;

			break;

		case CPUCLOCK_VIRT:

			if (expires_gt(cputime_expires->virt_exp, exp))

				cputime_expires->virt_exp = exp;

			break;

		case CPUCLOCK_SCHED:

			if (expires_gt(cputime_expires->sched_exp, exp))

				cputime_expires->sched_exp = exp;

			break;

		}

	if (CPUCLOCK_PERTHREAD(timer->it_clock))

		tick_dep_set_task(p, TICK_DEP_BIT_POSIX_TIMER);

	else

		tick_dep_set_signal(p->signal, TICK_DEP_BIT_POSIX_TIMER);

}

}



/*

 * The timer is locked, fire it and arrange for its reload.