This is a note to let you know that I've just added the patch titled
tick: Get rid of tick_period
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tick-get-rid-of-tick_period.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit f786046c8d8283c1e30b7d3b775822010000fa10
Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Date: Tue Nov 17 14:19:49 2020 +0100
tick: Get rid of tick_period
[ Upstream commit b996544916429946bf4934c1c01a306d1690972c ]
The variable tick_period is initialized to NSEC_PER_TICK / HZ during boot
and never updated again.
If NSEC_PER_TICK is not an integer multiple of HZ this computation is less
accurate than TICK_NSEC which has proper rounding in place.
Aside of the inaccuracy there is no reason for having this variable at
all. It's just a pointless indirection and all usage sites can just use the
TICK_NSEC constant.
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20201117132006.766643526@xxxxxxxxxxxxx
Stable-dep-of: e9523a0d8189 ("tick/common: Align tick period with the HZ tick.")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index e51778c312f1c..ce7339ff10d22 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -331,7 +331,7 @@ static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
bc_local = tick_do_periodic_broadcast();
if (clockevent_state_oneshot(dev)) {
- ktime_t next = ktime_add(dev->next_event, tick_period);
+ ktime_t next = ktime_add_ns(dev->next_event, TICK_NSEC);
clockevents_program_event(dev, next, true);
}
diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index 6c9c342dd0e53..92bf99d558b48 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -30,7 +30,6 @@ DEFINE_PER_CPU(struct tick_device, tick_cpu_device);
* Tick next event: keeps track of the tick time
*/
ktime_t tick_next_period;
-ktime_t tick_period;
/*
* tick_do_timer_cpu is a timer core internal variable which holds the CPU NR
@@ -88,7 +87,7 @@ static void tick_periodic(int cpu)
write_seqcount_begin(&jiffies_seq);
/* Keep track of the next tick event */
- tick_next_period = ktime_add(tick_next_period, tick_period);
+ tick_next_period = ktime_add_ns(tick_next_period, TICK_NSEC);
do_timer(1);
write_seqcount_end(&jiffies_seq);
@@ -127,7 +126,7 @@ void tick_handle_periodic(struct clock_event_device *dev)
* Setup the next period for devices, which do not have
* periodic mode:
*/
- next = ktime_add(next, tick_period);
+ next = ktime_add_ns(next, TICK_NSEC);
if (!clockevents_program_event(dev, next, false))
return;
@@ -173,7 +172,7 @@ void tick_setup_periodic(struct clock_event_device *dev, int broadcast)
for (;;) {
if (!clockevents_program_event(dev, next, false))
return;
- next = ktime_add(next, tick_period);
+ next = ktime_add_ns(next, TICK_NSEC);
}
}
}
@@ -220,7 +219,6 @@ static void tick_setup_device(struct tick_device *td,
tick_do_timer_cpu = cpu;
tick_next_period = ktime_get();
- tick_period = NSEC_PER_SEC / HZ;
#ifdef CONFIG_NO_HZ_FULL
/*
* The boot CPU may be nohz_full, in which case set
diff --git a/kernel/time/tick-internal.h b/kernel/time/tick-internal.h
index 5294f5b1f9550..e61c1244e7d46 100644
--- a/kernel/time/tick-internal.h
+++ b/kernel/time/tick-internal.h
@@ -15,7 +15,6 @@
DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
extern ktime_t tick_next_period;
-extern ktime_t tick_period;
extern int tick_do_timer_cpu __read_mostly;
extern void tick_setup_periodic(struct clock_event_device *dev, int broadcast);
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 3b00167656d78..1b5037ba4ec40 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -92,17 +92,17 @@ static void tick_do_update_jiffies64(ktime_t now)
write_seqcount_begin(&jiffies_seq);
delta = ktime_sub(now, tick_next_period);
- if (unlikely(delta >= tick_period)) {
+ if (unlikely(delta >= TICK_NSEC)) {
/* Slow path for long idle sleep times */
- s64 incr = ktime_to_ns(tick_period);
+ s64 incr = TICK_NSEC;
ticks += ktime_divns(delta, incr);
last_jiffies_update = ktime_add_ns(last_jiffies_update,
incr * ticks);
} else {
- last_jiffies_update = ktime_add(last_jiffies_update,
- tick_period);
+ last_jiffies_update = ktime_add_ns(last_jiffies_update,
+ TICK_NSEC);
}
do_timer(ticks);
@@ -112,7 +112,7 @@ static void tick_do_update_jiffies64(ktime_t now)
* pairs with the READ_ONCE() in the lockless quick check above.
*/
WRITE_ONCE(tick_next_period,
- ktime_add(last_jiffies_update, tick_period));
+ ktime_add_ns(last_jiffies_update, TICK_NSEC));
write_seqcount_end(&jiffies_seq);
raw_spin_unlock(&jiffies_lock);
@@ -659,7 +659,7 @@ static void tick_nohz_restart(struct tick_sched *ts, ktime_t now)
hrtimer_set_expires(&ts->sched_timer, ts->last_tick);
/* Forward the time to expire in the future */
- hrtimer_forward(&ts->sched_timer, now, tick_period);
+ hrtimer_forward(&ts->sched_timer, now, TICK_NSEC);
if (ts->nohz_mode == NOHZ_MODE_HIGHRES) {
hrtimer_start_expires(&ts->sched_timer,
@@ -1221,7 +1221,7 @@ static void tick_nohz_handler(struct clock_event_device *dev)
if (unlikely(ts->tick_stopped))
return;
- hrtimer_forward(&ts->sched_timer, now, tick_period);
+ hrtimer_forward(&ts->sched_timer, now, TICK_NSEC);
tick_program_event(hrtimer_get_expires(&ts->sched_timer), 1);
}
@@ -1258,7 +1258,7 @@ static void tick_nohz_switch_to_nohz(void)
next = tick_init_jiffy_update();
hrtimer_set_expires(&ts->sched_timer, next);
- hrtimer_forward_now(&ts->sched_timer, tick_period);
+ hrtimer_forward_now(&ts->sched_timer, TICK_NSEC);
tick_program_event(hrtimer_get_expires(&ts->sched_timer), 1);
tick_nohz_activate(ts, NOHZ_MODE_LOWRES);
}
@@ -1324,7 +1324,7 @@ static enum hrtimer_restart tick_sched_timer(struct hrtimer *timer)
if (unlikely(ts->tick_stopped))
return HRTIMER_NORESTART;
- hrtimer_forward(timer, now, tick_period);
+ hrtimer_forward(timer, now, TICK_NSEC);
return HRTIMER_RESTART;
}
@@ -1358,13 +1358,13 @@ void tick_setup_sched_timer(void)
/* Offset the tick to avert jiffies_lock contention. */
if (sched_skew_tick) {
- u64 offset = ktime_to_ns(tick_period) >> 1;
+ u64 offset = TICK_NSEC >> 1;
do_div(offset, num_possible_cpus());
offset *= smp_processor_id();
hrtimer_add_expires_ns(&ts->sched_timer, offset);
}
- hrtimer_forward(&ts->sched_timer, now, tick_period);
+ hrtimer_forward(&ts->sched_timer, now, TICK_NSEC);
hrtimer_start_expires(&ts->sched_timer, HRTIMER_MODE_ABS_PINNED_HARD);
tick_nohz_activate(ts, NOHZ_MODE_HIGHRES);
}
