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authorLinus Torvalds <torvalds@linux-foundation.org>2012-06-04 11:25:31 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-06-04 11:25:31 -0700
commitc22072bdf053b115a1126658100967dda00b5ecf (patch)
tree21520119dbbfce237a5005e9840105e86944c9cc /kernel
parent0640113be25d283e0ff77a9f041e1242182387f0 (diff)
parent62cf20b32aee4ae889a2eb40fd41c0eab73de970 (diff)
downloadop-kernel-dev-c22072bdf053b115a1126658100967dda00b5ecf.zip
op-kernel-dev-c22072bdf053b115a1126658100967dda00b5ecf.tar.gz
Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer updates from Thomas Gleixner: "The clocksource driver is pure hardware enablement and the skew option is default off, well tested and non dangerous." * 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: tick: Move skew_tick option into the HIGH_RES_TIMER section clocksource: em_sti: Add DT support clocksource: em_sti: Emma Mobile STI driver clockevents: Make clockevents_config() a global symbol tick: Add tick skew boot option
Diffstat (limited to 'kernel')
-rw-r--r--kernel/time/clockevents.c3
-rw-r--r--kernel/time/tick-sched.c18
2 files changed, 19 insertions, 2 deletions
diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
index 9cd928f..7e1ce01 100644
--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c
@@ -297,8 +297,7 @@ void clockevents_register_device(struct clock_event_device *dev)
}
EXPORT_SYMBOL_GPL(clockevents_register_device);
-static void clockevents_config(struct clock_event_device *dev,
- u32 freq)
+void clockevents_config(struct clock_event_device *dev, u32 freq)
{
u64 sec;
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 6a3a5b9..efd3866 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -814,6 +814,16 @@ static enum hrtimer_restart tick_sched_timer(struct hrtimer *timer)
return HRTIMER_RESTART;
}
+static int sched_skew_tick;
+
+static int __init skew_tick(char *str)
+{
+ get_option(&str, &sched_skew_tick);
+
+ return 0;
+}
+early_param("skew_tick", skew_tick);
+
/**
* tick_setup_sched_timer - setup the tick emulation timer
*/
@@ -831,6 +841,14 @@ void tick_setup_sched_timer(void)
/* Get the next period (per cpu) */
hrtimer_set_expires(&ts->sched_timer, tick_init_jiffy_update());
+ /* Offset the tick to avert xtime_lock contention. */
+ if (sched_skew_tick) {
+ u64 offset = ktime_to_ns(tick_period) >> 1;
+ do_div(offset, num_possible_cpus());
+ offset *= smp_processor_id();
+ hrtimer_add_expires_ns(&ts->sched_timer, offset);
+ }
+
for (;;) {
hrtimer_forward(&ts->sched_timer, now, tick_period);
hrtimer_start_expires(&ts->sched_timer,
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