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Message-ID: <TYCP286MB21466A2954F68505833BB0A1C683A@TYCP286MB2146.JPNP286.PROD.OUTLOOK.COM>
Date: Wed, 29 Nov 2023 18:35:18 +0800
From: Peng Liu <pngliu@...mail.com>
To: unlisted-recipients:; (no To-header on input)
Cc: frederic@...nel.org, tglx@...utronix.de, mingo@...nel.org,
linux-kernel@...r.kernel.org, liupeng17@...ovo.com
Subject: [PATCH v3 1/2] tick/nohz: Remove duplicate between tick_nohz_switch_to_nohz() and tick_setup_sched_timer()
From: Peng Liu <liupeng17@...ovo.com>
The ts->sched_timer initialization work of tick_nohz_switch_to_nohz()
is almost the same as that of tick_setup_sched_timer(), so adjust the
latter to get it reused by tick_nohz_switch_to_nohz().
This also makes low-res mode sched_timer benefit from the tick skew
boot option.
Signed-off-by: Peng Liu <liupeng17@...ovo.com>
---
Changes in v3:
- Remove the first``#ifdef CONFIG_HIGH_RES_TIMERS'' in tick_setup_sched_timer()
in patch 2/2
- Add comment on sched_skew_tick introduced to low-res mode tick_sched setup
- Replace hrtimer_forward() with hrtimer_forward_now() in tick_setup_sched_timer()
- Remove the sedond ``#ifdef CONFIG_HIGH_RES_TIMERS'' in tick_setup_sched_timer()
- Move tick_nohz_highres_handler() ahead to avoid additional declaration
Changes in v2:
- Fix build warning: Function parameter or member 'mode' not described in
'tick_setup_sched_timer'
- Fix build error: use of undeclared identifier 'tick_nohz_highres_handler'
- Fix build error: use of undeclared identifier 'sched_skew_tick'
---
kernel/time/hrtimer.c | 2 +-
kernel/time/tick-sched.c | 38 +++++++++++++++++---------------------
kernel/time/tick-sched.h | 2 +-
3 files changed, 19 insertions(+), 23 deletions(-)
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 760793998cdd..355b5a957f7f 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -746,7 +746,7 @@ static void hrtimer_switch_to_hres(void)
base->hres_active = 1;
hrtimer_resolution = HIGH_RES_NSEC;
- tick_setup_sched_timer();
+ tick_setup_sched_timer(NOHZ_MODE_HIGHRES);
/* "Retrigger" the interrupt to get things going */
retrigger_next_event(NULL);
}
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index be77b021e5d6..d25039f07838 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -1430,9 +1430,6 @@ static inline void tick_nohz_activate(struct tick_sched *ts, int mode)
*/
static void tick_nohz_switch_to_nohz(void)
{
- struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched);
- ktime_t next;
-
if (!tick_nohz_enabled)
return;
@@ -1441,16 +1438,9 @@ static void tick_nohz_switch_to_nohz(void)
/*
* Recycle the hrtimer in 'ts', so we can share the
- * hrtimer_forward_now() function with the highres code.
+ * highres code.
*/
- hrtimer_init(&ts->sched_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_HARD);
- /* Get the next period */
- next = tick_init_jiffy_update();
-
- hrtimer_set_expires(&ts->sched_timer, next);
- 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);
+ tick_setup_sched_timer(NOHZ_MODE_LOWRES);
}
static inline void tick_nohz_irq_enter(void)
@@ -1529,7 +1519,9 @@ static enum hrtimer_restart tick_nohz_highres_handler(struct hrtimer *timer)
return HRTIMER_RESTART;
}
+#endif /* HIGH_RES_TIMERS */
+#if defined CONFIG_NO_HZ_COMMON || defined CONFIG_HIGH_RES_TIMERS
static int sched_skew_tick;
static int __init skew_tick(char *str)
@@ -1542,15 +1534,18 @@ early_param("skew_tick", skew_tick);
/**
* tick_setup_sched_timer - setup the tick emulation timer
+ * @mode: tick_nohz_mode to setup for
*/
-void tick_setup_sched_timer(void)
+void tick_setup_sched_timer(int mode)
{
struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched);
- ktime_t now = ktime_get();
/* Emulate tick processing via per-CPU hrtimers: */
hrtimer_init(&ts->sched_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_HARD);
- ts->sched_timer.function = tick_nohz_highres_handler;
+#ifdef CONFIG_HIGH_RES_TIMERS
+ if (mode == NOHZ_MODE_HIGHRES)
+ ts->sched_timer.function = tick_nohz_highres_handler;
+#endif
/* Get the next period (per-CPU) */
hrtimer_set_expires(&ts->sched_timer, tick_init_jiffy_update());
@@ -1563,13 +1558,14 @@ void tick_setup_sched_timer(void)
hrtimer_add_expires_ns(&ts->sched_timer, offset);
}
- 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);
+ hrtimer_forward_now(&ts->sched_timer, TICK_NSEC);
+ if (mode == NOHZ_MODE_HIGHRES)
+ hrtimer_start_expires(&ts->sched_timer, HRTIMER_MODE_ABS_PINNED_HARD);
+ else
+ tick_program_event(hrtimer_get_expires(&ts->sched_timer), 1);
+ tick_nohz_activate(ts, mode);
}
-#endif /* HIGH_RES_TIMERS */
-#if defined CONFIG_NO_HZ_COMMON || defined CONFIG_HIGH_RES_TIMERS
void tick_cancel_sched_timer(int cpu)
{
struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
@@ -1581,7 +1577,7 @@ void tick_cancel_sched_timer(int cpu)
memset(ts, 0, sizeof(*ts));
}
-#endif
+#endif /* CONFIG_NO_HZ_COMMON || CONFIG_HIGH_RES_TIMERS */
/*
* Async notification about clocksource changes
diff --git a/kernel/time/tick-sched.h b/kernel/time/tick-sched.h
index 5ed5a9d41d5a..35808bbb8a47 100644
--- a/kernel/time/tick-sched.h
+++ b/kernel/time/tick-sched.h
@@ -102,7 +102,7 @@ struct tick_sched {
extern struct tick_sched *tick_get_tick_sched(int cpu);
-extern void tick_setup_sched_timer(void);
+extern void tick_setup_sched_timer(int mode);
#if defined CONFIG_NO_HZ_COMMON || defined CONFIG_HIGH_RES_TIMERS
extern void tick_cancel_sched_timer(int cpu);
#else
--
2.34.1
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