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Date: Tue, 7 Apr 2015 07:40:53 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
Peter Zijlstra <peterz@...radead.org>
Cc: linaro-kernel@...ts.linaro.org, linux-kernel@...r.kernel.org,
Preeti U Murthy <preeti@...ux.vnet.ibm.com>,
Viresh Kumar <viresh.kumar@...aro.org>
Subject: [PATCH V2 2/2] hrtimer: Iterate only over active clock-bases
At several instances we iterate over all possible clock-bases for a
particular cpu-base. Whereas, we only need to iterate over active bases.
We already have per cpu-base 'active_bases' field, which is updated on
addition/removal of hrtimers.
This patch creates for_each_active_base(), which uses 'active_bases' to
iterate only over active bases.
This also updates code which iterates over clock-bases.
Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
---
kernel/time/hrtimer.c | 65 ++++++++++++++++++++++++++++++++-------------------
1 file changed, 41 insertions(+), 24 deletions(-)
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 3152f327c988..9da63e9ee63b 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -110,6 +110,31 @@ static inline int hrtimer_clockid_to_base(clockid_t clock_id)
}
+static inline int __next_bit(unsigned int active_bases, int bit)
+{
+ do {
+ if (active_bases & (1 << bit))
+ return bit;
+ } while (++bit < HRTIMER_MAX_CLOCK_BASES);
+
+ /* We should never reach here */
+ return 0;
+}
+
+/*
+ * for_each_active_base: iterate over all active clock bases
+ * @_bit: 'int' variable for internal purpose
+ * @_base: holds pointer to a active clock base
+ * @_cpu_base: cpu base to iterate on
+ * @_active_bases: 'unsigned int' variable for internal purpose
+ */
+#define for_each_active_base(_bit, _base, _cpu_base, _active_bases) \
+ for ((_active_bases) = (_cpu_base)->active_bases, (_bit) = -1; \
+ (_active_bases) && \
+ ((_bit) = __next_bit(_active_bases, ++_bit), \
+ (_base) = (_cpu_base)->clock_base + _bit); \
+ (_active_bases) &= ~(1 << (_bit)))
+
/*
* Get the coarse grained time at the softirq based on xtime and
* wall_to_monotonic.
@@ -443,19 +468,15 @@ static inline void debug_deactivate(struct hrtimer *timer)
#if defined(CONFIG_NO_HZ_COMMON) || defined(CONFIG_HIGH_RES_TIMERS)
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;
ktime_t expires, expires_next = { .tv64 = KTIME_MAX };
+ struct hrtimer *timer;
+ unsigned int active_bases;
int i;
- for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) {
- struct timerqueue_node *next;
- struct hrtimer *timer;
-
- next = timerqueue_getnext(&base->active);
- if (!next)
- continue;
-
- timer = container_of(next, struct hrtimer, node);
+ for_each_active_base(i, base, cpu_base, active_bases) {
+ timer = container_of(timerqueue_getnext(&base->active),
+ struct hrtimer, node);
expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
if (expires.tv64 < expires_next.tv64)
expires_next = expires;
@@ -1245,6 +1266,8 @@ void hrtimer_interrupt(struct clock_event_device *dev)
{
struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
ktime_t expires_next, now, entry_time, delta;
+ struct hrtimer_clock_base *base;
+ unsigned int active_bases;
int i, retries = 0;
BUG_ON(!cpu_base->hres_active);
@@ -1264,15 +1287,10 @@ void hrtimer_interrupt(struct clock_event_device *dev)
*/
cpu_base->expires_next.tv64 = KTIME_MAX;
- for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
- struct hrtimer_clock_base *base;
+ for_each_active_base(i, base, cpu_base, active_bases) {
struct timerqueue_node *node;
ktime_t basenow;
- if (!(cpu_base->active_bases & (1 << i)))
- continue;
-
- base = cpu_base->clock_base + i;
basenow = ktime_add(now, base->offset);
while ((node = timerqueue_getnext(&base->active))) {
@@ -1435,16 +1453,13 @@ void hrtimer_run_queues(void)
struct timerqueue_node *node;
struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
struct hrtimer_clock_base *base;
+ unsigned int active_bases;
int index, 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;
-
+ for_each_active_base(index, base, cpu_base, active_bases) {
if (gettime) {
hrtimer_get_softirq_time(cpu_base);
gettime = 0;
@@ -1665,6 +1680,8 @@ static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
static void migrate_hrtimers(int scpu)
{
struct hrtimer_cpu_base *old_base, *new_base;
+ struct hrtimer_clock_base *clock_base;
+ unsigned int active_bases;
int i;
BUG_ON(cpu_online(scpu));
@@ -1680,9 +1697,9 @@ static void migrate_hrtimers(int scpu)
raw_spin_lock(&new_base->lock);
raw_spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
- for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
- migrate_hrtimer_list(&old_base->clock_base[i],
- &new_base->clock_base[i]);
+ for_each_active_base(i, clock_base, old_base, active_bases) {
+ migrate_hrtimer_list(clock_base,
+ &new_base->clock_base[clock_base->index]);
}
raw_spin_unlock(&old_base->lock);
--
2.3.0.rc0.44.ga94655d
--
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