The hrtimer softirq is called from the timer softirq every tick.
Retrieve the current time from xtime and wall_to_monotonic instead of
calling base->get_time() for each timer base. Store the time in the
base structure and provide a hook once clock source abstractions are in
place and to keep the code open for new base clocks.
Based on a patch from: Roman Zippel <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
include/linux/hrtimer.h | 20 ++++++++++++--------
kernel/hrtimer.c | 28 ++++++++++++++++++++++++++--
2 files changed, 38 insertions(+), 10 deletions(-)
Index: linux-2.6.16-updates/kernel/hrtimer.c
===================================================================
--- linux-2.6.16-updates.orig/kernel/hrtimer.c
+++ linux-2.6.16-updates/kernel/hrtimer.c
@@ -123,6 +123,26 @@ void ktime_get_ts(struct timespec *ts)
EXPORT_SYMBOL_GPL(ktime_get_ts);
/*
+ * Get the coarse grained time at the softirq based on xtime and
+ * wall_to_monotonic.
+ */
+static void hrtimer_get_softirq_time(struct hrtimer_base *base)
+{
+ ktime_t xtim, tomono;
+ unsigned long seq;
+
+ do {
+ seq = read_seqbegin(&xtime_lock);
+ xtim = timespec_to_ktime(xtime);
+ tomono = timespec_to_ktime(wall_to_monotonic);
+
+ } while (read_seqretry(&xtime_lock, seq));
+
+ base[CLOCK_REALTIME].softirq_time = xtim;
+ base[CLOCK_MONOTONIC].softirq_time = ktime_add(xtim, tomono);
+}
+
+/*
* Functions and macros which are different for UP/SMP systems are kept in a
* single place
*/
@@ -586,9 +606,11 @@ int hrtimer_get_res(const clockid_t whic
*/
static inline void run_hrtimer_queue(struct hrtimer_base *base)
{
- ktime_t now = base->get_time();
struct rb_node *node;
+ if (base->get_softirq_time)
+ base->softirq_time = base->get_softirq_time();
+
spin_lock_irq(&base->lock);
while ((node = base->first)) {
@@ -598,7 +620,7 @@ static inline void run_hrtimer_queue(str
void *data;
timer = rb_entry(node, struct hrtimer, node);
- if (now.tv64 <= timer->expires.tv64)
+ if (base->softirq_time.tv64 <= timer->expires.tv64)
break;
fn = timer->function;
@@ -641,6 +663,8 @@ void hrtimer_run_queues(void)
struct hrtimer_base *base = __get_cpu_var(hrtimer_bases);
int i;
+ hrtimer_get_softirq_time(base);
+
for (i = 0; i < MAX_HRTIMER_BASES; i++)
run_hrtimer_queue(&base[i]);
}
Index: linux-2.6.16-updates/include/linux/hrtimer.h
===================================================================
--- linux-2.6.16-updates.orig/include/linux/hrtimer.h
+++ linux-2.6.16-updates/include/linux/hrtimer.h
@@ -72,14 +72,16 @@ struct hrtimer {
/**
* struct hrtimer_base - the timer base for a specific clock
*
- * @index: clock type index for per_cpu support when moving a timer
- * to a base on another cpu.
- * @lock: lock protecting the base and associated timers
- * @active: red black tree root node for the active timers
- * @first: pointer to the timer node which expires first
- * @resolution: the resolution of the clock, in nanoseconds
- * @get_time: function to retrieve the current time of the clock
- * @curr_timer: the timer which is executing a callback right now
+ * @index: clock type index for per_cpu support when moving a timer
+ * to a base on another cpu.
+ * @lock: lock protecting the base and associated timers
+ * @active: red black tree root node for the active timers
+ * @first: pointer to the timer node which expires first
+ * @resolution: the resolution of the clock, in nanoseconds
+ * @get_time: function to retrieve the current time of the clock
+ * @get_sofirq_time: function to retrieve the current time from the softirq
+ * @curr_timer: the timer which is executing a callback right now
+ * @softirq_time: the time when running the hrtimer queue in the softirq
*/
struct hrtimer_base {
clockid_t index;
@@ -88,7 +90,9 @@ struct hrtimer_base {
struct rb_node *first;
ktime_t resolution;
ktime_t (*get_time)(void);
+ ktime_t (*get_softirq_time)(void);
struct hrtimer *curr_timer;
+ ktime_t softirq_time;
};
/*
--
-
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