[tip:timers/core] hrtimer: Use cpu_base-> active_base for hotpath iterators

[tip-bot for Thomas Gleixner <tipbot@zytor.com>]

Commit-ID:  34aee88a02ba296a8e8c9523cdf77147731903f1
Gitweb:     http://git.kernel.org/tip/34aee88a02ba296a8e8c9523cdf77147731903f1
Author:     Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Tue, 14 Apr 2015 21:08:41 +0000
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Wed, 22 Apr 2015 17:06:49 +0200

hrtimer: Use cpu_base->active_base for hotpath iterators

The active_bases field is guaranteed to be in sync with the timerqueue
of the corresponding clock base. So we can use it for iterating over
the clock bases. This allows to break out early if no more active
clock bases are available and avoids touching the cache lines of
inactive clock bases.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
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/20150414203501.322887675@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 kernel/time/hrtimer.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 9bbfe33..fce0ccf 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -419,16 +419,16 @@ 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 };
-	int i;
+	unsigned int active = cpu_base->active_bases;
 
-	for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) {
+	for (; active; base++, active >>= 1) {
 		struct timerqueue_node *next;
 		struct hrtimer *timer;
 
-		next = timerqueue_getnext(&base->active);
-		if (!next)
+		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);
 		if (expires.tv64 < expires_next.tv64)
@@ -1214,17 +1214,16 @@ static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base,
 
 static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now)
 {
-	int i;
+	struct hrtimer_clock_base *base = cpu_base->clock_base;
+	unsigned int active = cpu_base->active_bases;
 
-	for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
-		struct hrtimer_clock_base *base;
+	for (; active; base++, active >>= 1) {
 		struct timerqueue_node *node;
 		ktime_t basenow;
 
-		if (!(cpu_base->active_bases & (1 << i)))
+		if (!(active & 0x01))
 			continue;
 
-		base = cpu_base->clock_base + i;
 		basenow = ktime_add(now, base->offset);
 
 		while ((node = timerqueue_getnext(&base->active))) {