Commit-ID: c272ca58c3ec5631f4ab507489d9477f74efe645 Gitweb: https://git.kernel.org/tip/c272ca58c3ec5631f4ab507489d9477f74efe645 Author: Anna-Maria Gleixner <[email protected]> AuthorDate: Thu, 21 Dec 2017 11:41:39 +0100 Committer: Ingo Molnar <[email protected]> CommitDate: Tue, 16 Jan 2018 02:35:46 +0100
hrtimer: Switch 'for' loop to _ffs() evaluation 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. The functionallity is outsourced into its own function and is called via a macro as suggested by Peter Zijlstra. Suggested-by: Peter Zijlstra <[email protected]> Signed-off-by: Anna-Maria Gleixner <[email protected]> Cc: Christoph Hellwig <[email protected]> Cc: John Stultz <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- kernel/time/hrtimer.c | 31 +++++++++++++++++++++---------- 1 file changed, 21 insertions(+), 10 deletions(-) diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c index f4f4658..cfcf8de 100644 --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -448,6 +448,23 @@ static inline void debug_deactivate(struct hrtimer *timer) trace_hrtimer_cancel(timer); } +static struct hrtimer_clock_base * +__next_base(struct hrtimer_cpu_base *cpu_base, unsigned int *active) +{ + unsigned int idx; + + if (!*active) + return NULL; + + idx = __ffs(*active); + *active &= ~(1U << idx); + + return &cpu_base->clock_base[idx]; +} + +#define for_each_active_base(base, cpu_base, active) \ + while ((base = __next_base((cpu_base), &(active)))) + #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) @@ -459,18 +476,15 @@ static inline void hrtimer_update_next_timer(struct hrtimer_cpu_base *cpu_base, static ktime_t __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base) { - struct hrtimer_clock_base *base = cpu_base->clock_base; + struct hrtimer_clock_base *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) { + for_each_active_base(base, cpu_base, active) { struct timerqueue_node *next; struct hrtimer *timer; - if (!(active & 0x01)) - continue; - next = timerqueue_getnext(&base->active); timer = container_of(next, struct hrtimer, node); expires = ktime_sub(hrtimer_get_expires(timer), base->offset); @@ -1241,16 +1255,13 @@ static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base, static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now) { - struct hrtimer_clock_base *base = cpu_base->clock_base; + struct hrtimer_clock_base *base; unsigned int active = cpu_base->active_bases; - for (; active; base++, active >>= 1) { + for_each_active_base(base, cpu_base, active) { struct timerqueue_node *node; ktime_t basenow; - if (!(active & 0x01)) - continue; - basenow = ktime_add(now, base->offset); while ((node = timerqueue_getnext(&base->active))) {
