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author | Thomas Gleixner <tglx@linutronix.de> | 2015-04-14 21:08:49 +0000 |
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committer | Thomas Gleixner <tglx@linutronix.de> | 2015-04-22 17:06:50 +0200 |
commit | 895bdfa793f6e912d1a58fc445b3dd4d686f7bd3 (patch) | |
tree | df602d9bb8097eb9cd0bd6f98addc9b5f5cd333d /kernel | |
parent | b97f44c9b658d52e0139c947ea5519e51ba38d81 (diff) | |
download | op-kernel-dev-895bdfa793f6e912d1a58fc445b3dd4d686f7bd3.zip op-kernel-dev-895bdfa793f6e912d1a58fc445b3dd4d686f7bd3.tar.gz |
hrtimer: Keep pointer to first timer and simplify __remove_hrtimer()
__remove_hrtimer() needs to evaluate the expiry time to figure out
whether the timer which is removed is eventually the first expiring
timer on the cpu. Keep a pointer to it, which is lazily updated, so we
can avoid the evaluation dance and retrieve the information from there.
Generates slightly better code.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203501.752838019@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/time/hrtimer.c | 46 |
1 files changed, 28 insertions, 18 deletions
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c index 0cd1e0b..30178d0 100644 --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -415,12 +415,21 @@ static inline void debug_deactivate(struct hrtimer *timer) } #if defined(CONFIG_NO_HZ_COMMON) || defined(CONFIG_HIGH_RES_TIMERS) +static inline void hrtimer_update_next_timer(struct hrtimer_cpu_base *cpu_base, + struct hrtimer *timer) +{ +#ifdef CONFIG_HIGH_RES_TIMERS + cpu_base->next_timer = timer; +#endif +} + static ktime_t __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base) { struct hrtimer_clock_base *base = cpu_base->clock_base; ktime_t expires, expires_next = { .tv64 = KTIME_MAX }; unsigned int active = cpu_base->active_bases; + hrtimer_update_next_timer(cpu_base, NULL); for (; active; base++, active >>= 1) { struct timerqueue_node *next; struct hrtimer *timer; @@ -431,8 +440,10 @@ static ktime_t __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base) next = timerqueue_getnext(&base->active); timer = container_of(next, struct hrtimer, node); expires = ktime_sub(hrtimer_get_expires(timer), base->offset); - if (expires.tv64 < expires_next.tv64) + if (expires.tv64 < expires_next.tv64) { expires_next = expires; + hrtimer_update_next_timer(cpu_base, timer); + } } /* * clock_was_set() might have changed base->offset of any of @@ -597,6 +608,8 @@ static int hrtimer_reprogram(struct hrtimer *timer, if (cpu_base->in_hrtirq) return 0; + cpu_base->next_timer = timer; + /* * If a hang was detected in the last timer interrupt then we * do not schedule a timer which is earlier than the expiry @@ -868,30 +881,27 @@ static void __remove_hrtimer(struct hrtimer *timer, unsigned long newstate, int reprogram) { struct hrtimer_cpu_base *cpu_base = base->cpu_base; - struct timerqueue_node *next_timer; + unsigned int state = timer->state; - if (!(timer->state & HRTIMER_STATE_ENQUEUED)) - goto out; + timer->state = newstate; + if (!(state & HRTIMER_STATE_ENQUEUED)) + return; - next_timer = timerqueue_getnext(&base->active); if (!timerqueue_del(&base->active, &timer->node)) cpu_base->active_bases &= ~(1 << base->index); - if (&timer->node == next_timer) { #ifdef CONFIG_HIGH_RES_TIMERS - /* Reprogram the clock event device. if enabled */ - if (reprogram && cpu_base->hres_active) { - ktime_t expires; - - expires = ktime_sub(hrtimer_get_expires(timer), - base->offset); - if (cpu_base->expires_next.tv64 == expires.tv64) - hrtimer_force_reprogram(cpu_base, 1); - } + /* + * Note: If reprogram is false we do not update + * cpu_base->next_timer. This happens when we remove the first + * timer on a remote cpu. No harm as we never dereference + * cpu_base->next_timer. So the worst thing what can happen is + * an superflous call to hrtimer_force_reprogram() on the + * remote cpu later on if the same timer gets enqueued again. + */ + if (reprogram && timer == cpu_base->next_timer) + hrtimer_force_reprogram(cpu_base, 1); #endif - } -out: - timer->state = newstate; } /* |