2015-04-14 21:09:12

by Thomas Gleixner

Subject: [patch 17/39] tick: sched: Remove hrtimer_active() checks

hrtimer_start() enforces a timer interrupt if the timer is already
expired. Get rid of the checks and the forward loop.

Signed-off-by: Thomas Gleixner <[email protected]>
Cc: John Stultz <[email protected]>
Cc: Preeti U Murthy <[email protected]>
Cc: Marcelo Tosatti <[email protected]>
Cc: Frederic Weisbecker <[email protected]>

---
kernel/time/tick-sched.c | 19 ++++---------------
1 file changed, 4 insertions(+), 15 deletions(-)

Index: tip/kernel/time/tick-sched.c
===================================================================
--- tip.orig/kernel/time/tick-sched.c
+++ tip/kernel/time/tick-sched.c
@@ -696,11 +696,9 @@ static ktime_t tick_nohz_stop_sched_tick
if (ts->nohz_mode == NOHZ_MODE_HIGHRES) {
hrtimer_start(&ts->sched_timer, expires,
HRTIMER_MODE_ABS_PINNED);
- /* Check, if the timer was already in the past */
- if (hrtimer_active(&ts->sched_timer))
- goto out;
+ goto out;
} else if (!tick_program_event(expires, 0))
- goto out;
+ goto out;
/*
* We are past the event already. So we crossed a
* jiffie boundary. Update jiffies and raise the
@@ -888,8 +886,6 @@ static void tick_nohz_restart(struct tic
if (ts->nohz_mode == NOHZ_MODE_HIGHRES) {
hrtimer_start_expires(&ts->sched_timer,
HRTIMER_MODE_ABS_PINNED);
- /* Check, if the timer was already in the past */
- if (hrtimer_active(&ts->sched_timer))
break;
} else {
if (!tick_program_event(
@@ -1167,15 +1163,8 @@ void tick_setup_sched_timer(void)
hrtimer_add_expires_ns(&ts->sched_timer, offset);
}

- for (;;) {
- hrtimer_forward(&ts->sched_timer, now, tick_period);
- hrtimer_start_expires(&ts->sched_timer,
- HRTIMER_MODE_ABS_PINNED);
- /* Check, if the timer was already in the past */
- if (hrtimer_active(&ts->sched_timer))
- break;
- now = ktime_get();
- }
+ hrtimer_forward(&ts->sched_timer, now, tick_period);
+ hrtimer_start_expires(&ts->sched_timer, HRTIMER_MODE_ABS_PINNED);

#ifdef CONFIG_NO_HZ_COMMON
if (tick_nohz_enabled) {

2015-04-16 13:37:36

by Frederic Weisbecker

Subject: Re: [patch 17/39] tick: sched: Remove hrtimer_active() checks

On Tue, Apr 14, 2015 at 09:08:52PM -0000, Thomas Gleixner wrote:
> hrtimer_start() enforces a timer interrupt if the timer is already
> expired. Get rid of the checks and the forward loop.
>
> Signed-off-by: Thomas Gleixner <[email protected]>
> Cc: John Stultz <[email protected]>
> Cc: Preeti U Murthy <[email protected]>
> Cc: Marcelo Tosatti <[email protected]>

Reviewed-by: Frederic Weisbecker <[email protected]>

2015-04-22 19:09:57

by tip-bot for Vasyl Gomonovych

Subject: [tip:timers/core] tick: sched: Remove hrtimer_active() checks

Commit-ID: afc08b15cc2a3d2c48cbd427be8e0eea05698363
Gitweb: http://git.kernel.org/tip/afc08b15cc2a3d2c48cbd427be8e0eea05698363
Author: Thomas Gleixner <[email protected]>
AuthorDate: Tue, 14 Apr 2015 21:08:52 +0000
Committer: Thomas Gleixner <[email protected]>
CommitDate: Wed, 22 Apr 2015 17:06:50 +0200

tick: sched: Remove hrtimer_active() checks

hrtimer_start() enforces a timer interrupt if the timer is already
expired. Get rid of the checks and the forward loop.

Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Frederic Weisbecker <[email protected]>
Acked-by: Peter Zijlstra <[email protected]>
Cc: Preeti U Murthy <[email protected]>
Cc: Viresh Kumar <[email protected]>
Cc: Marcelo Tosatti <[email protected]>
Cc: John Stultz <[email protected]>
Cc: Marcelo Tosatti <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>

---
kernel/time/tick-sched.c | 19 ++++---------------
1 file changed, 4 insertions(+), 15 deletions(-)

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 9142591..dc586c3 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -696,11 +696,9 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts,
if (ts->nohz_mode == NOHZ_MODE_HIGHRES) {
hrtimer_start(&ts->sched_timer, expires,
HRTIMER_MODE_ABS_PINNED);
- /* Check, if the timer was already in the past */
- if (hrtimer_active(&ts->sched_timer))
- goto out;
+ goto out;
} else if (!tick_program_event(expires, 0))
- goto out;
+ goto out;
/*
* We are past the event already. So we crossed a
* jiffie boundary. Update jiffies and raise the
@@ -888,8 +886,6 @@ static void tick_nohz_restart(struct tick_sched *ts, ktime_t now)
if (ts->nohz_mode == NOHZ_MODE_HIGHRES) {
hrtimer_start_expires(&ts->sched_timer,
HRTIMER_MODE_ABS_PINNED);
- /* Check, if the timer was already in the past */
- if (hrtimer_active(&ts->sched_timer))
break;
} else {
if (!tick_program_event(
@@ -1167,15 +1163,8 @@ void tick_setup_sched_timer(void)
hrtimer_add_expires_ns(&ts->sched_timer, offset);
}

- for (;;) {
- hrtimer_forward(&ts->sched_timer, now, tick_period);
- hrtimer_start_expires(&ts->sched_timer,
- HRTIMER_MODE_ABS_PINNED);
- /* Check, if the timer was already in the past */
- if (hrtimer_active(&ts->sched_timer))
- break;
- now = ktime_get();
- }
+ hrtimer_forward(&ts->sched_timer, now, tick_period);
+ hrtimer_start_expires(&ts->sched_timer, HRTIMER_MODE_ABS_PINNED);

#ifdef CONFIG_NO_HZ_COMMON
if (tick_nohz_enabled) {