[RFC patch 2/5] hrtimer: Make use of the active bases bitfield

[Thomas Gleixner]

Instead of looping through all bases, find the active ones via the
cpu_base->active_bases bit field.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
 kernel/hrtimer.c |   33 +++++++++++++++++++++------------
 1 file changed, 21 insertions(+), 12 deletions(-)

Index: tip/kernel/hrtimer.c
===================================================================
--- tip.orig/kernel/hrtimer.c
+++ tip/kernel/hrtimer.c
@@ -1284,7 +1284,8 @@ void hrtimer_interrupt(struct clock_even
 {
 	struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
 	ktime_t expires_next, now, entry_time, delta;
-	int i, retries = 0;
+	unsigned long bases;
+	int retries = 0;
 
 	BUG_ON(!cpu_base->hres_active);
 	cpu_base->nr_events++;
@@ -1302,16 +1303,18 @@ retry:
 	 * this CPU.
 	 */
 	cpu_base->expires_next.tv64 = KTIME_MAX;
+	bases = cpu_base->active_bases;
 
-	for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
+	while (bases) {
 		struct hrtimer_clock_base *base;
 		struct timerqueue_node *node;
 		ktime_t basenow;
+		int idx;
 
-		if (!(cpu_base->active_bases & (1 << i)))
-			continue;
+		idx = __ffs(bases);
+		bases &= ~(1 << idx);
 
-		base = cpu_base->clock_base + i;
+		base = cpu_base->clock_base + idx;
 		basenow = ktime_add(now, base->offset);
 
 		while ((node = timerqueue_getnext(&base->active))) {
@@ -1479,18 +1482,24 @@ void hrtimer_run_pending(void)
  */
 void hrtimer_run_queues(void)
 {
-	struct timerqueue_node *node;
 	struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
-	struct hrtimer_clock_base *base;
-	int index, gettime = 1;
+	unsigned long bases;
+	int gettime = 1;
 
 	if (hrtimer_hres_active())
 		return;
 
-	for (index = 0; index < HRTIMER_MAX_CLOCK_BASES; index++) {
-		base = &cpu_base->clock_base[index];
-		if (!timerqueue_getnext(&base->active))
-			continue;
+	bases = cpu_base->active_bases;
+
+	while (bases) {
+		struct hrtimer_clock_base *base;
+		struct timerqueue_node *node;
+		int idx;
+
+		idx = __ffs(bases);
+		bases &= ~(1 << idx);
+
+		base = &cpu_base->clock_base[idx];
 
 		if (gettime) {
 			hrtimer_get_softirq_time(cpu_base);


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