From: Anna-Maria Gleixner <[email protected]> Looping over all clock bases to find active bits is suboptimal if not all bases are active.
Avoid this by converting it to a __ffs() evaluation. Signed-off-by: Anna-Maria Gleixner <[email protected]> --- kernel/time/hrtimer.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -465,17 +465,18 @@ static inline void hrtimer_update_next_t static ktime_t __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base) { - struct hrtimer_clock_base *base = cpu_base->clock_base; unsigned int active = cpu_base->active_bases; ktime_t expires, expires_next = KTIME_MAX; hrtimer_update_next_timer(cpu_base, NULL); - for (; active; base++, active >>= 1) { + while (active) { + unsigned int id = __ffs(active); + struct hrtimer_clock_base *base; struct timerqueue_node *next; struct hrtimer *timer; - if (!(active & 0x01)) - continue; + active &= ~(1U << id); + base = cpu_base->clock_base + id; next = timerqueue_getnext(&base->active); timer = container_of(next, struct hrtimer, node); @@ -1242,15 +1243,16 @@ static void __run_hrtimer(struct hrtimer static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now) { - struct hrtimer_clock_base *base = cpu_base->clock_base; unsigned int active = cpu_base->active_bases; - for (; active; base++, active >>= 1) { + while (active) { + unsigned int id = __ffs(active); + struct hrtimer_clock_base *base; struct timerqueue_node *node; ktime_t basenow; - if (!(active & 0x01)) - continue; + active &= ~(1U << id); + base = cpu_base->clock_base + id; basenow = ktime_add(now, base->offset);
