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Message-ID: <TYCP286MB2146C94F0A30EA8F7FEF8F14C683A@TYCP286MB2146.JPNP286.PROD.OUTLOOK.COM>
Date: Wed, 29 Nov 2023 18:35:30 +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 2/2] tick/nohz: Remove duplicate between tick_nohz_lowres_handler() and tick_nohz_highres_handler()
From: Peng Liu <liupeng17@...ovo.com>
tick_nohz_lowres_handler() does the same work as tick_nohz_highres_handler()
plus the clockevent device reprogramming, so should reuse the latter.
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/tick-sched.c | 96 ++++++++++++++++------------------------
1 file changed, 38 insertions(+), 58 deletions(-)
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index d25039f07838..a045425b8bf5 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -255,6 +255,41 @@ static void tick_sched_handle(struct tick_sched *ts, struct pt_regs *regs)
update_process_times(user_mode(regs));
profile_tick(CPU_PROFILING);
}
+
+/*
+ * We rearm the timer until we get disabled by the idle code.
+ * Called with interrupts disabled.
+ */
+static enum hrtimer_restart tick_nohz_highres_handler(struct hrtimer *timer)
+{
+ struct tick_sched *ts =
+ container_of(timer, struct tick_sched, sched_timer);
+ struct pt_regs *regs = get_irq_regs();
+ ktime_t now = ktime_get();
+
+ tick_sched_do_timer(ts, now);
+
+ /*
+ * Do not call when we are not in IRQ context and have
+ * no valid 'regs' pointer
+ */
+ if (regs)
+ tick_sched_handle(ts, regs);
+ else
+ ts->next_tick = 0;
+
+ /*
+ * In dynticks mode, tick reprogram is deferred:
+ * - to the idle task if in dynticks-idle
+ * - to IRQ exit if in full-dynticks.
+ */
+ if (unlikely(ts->tick_stopped))
+ return HRTIMER_NORESTART;
+
+ hrtimer_forward(timer, now, TICK_NSEC);
+
+ return HRTIMER_RESTART;
+}
#endif
#ifdef CONFIG_NO_HZ_FULL
@@ -1389,30 +1424,17 @@ void tick_nohz_idle_exit(void)
* infrastructure actually relies on the tick itself as a backend in
* low-resolution mode (see hrtimer_run_queues()).
*
- * This low-resolution handler still makes use of some hrtimer APIs meanwhile
- * for convenience with expiration calculation and forwarding.
+ * This low-resolution handler still reuse tick_nohz_highres_handler() since
+ * most of the work is independent of the clockevent level.
*/
static void tick_nohz_lowres_handler(struct clock_event_device *dev)
{
struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched);
- struct pt_regs *regs = get_irq_regs();
- ktime_t now = ktime_get();
dev->next_event = KTIME_MAX;
- tick_sched_do_timer(ts, now);
- tick_sched_handle(ts, regs);
-
- /*
- * In dynticks mode, tick reprogram is deferred:
- * - to the idle task if in dynticks-idle
- * - to IRQ exit if in full-dynticks.
- */
- if (likely(!ts->tick_stopped)) {
- hrtimer_forward(&ts->sched_timer, now, TICK_NSEC);
+ if (likely(tick_nohz_highres_handler(&ts->sched_timer) == HRTIMER_RESTART))
tick_program_event(hrtimer_get_expires(&ts->sched_timer), 1);
- }
-
}
static inline void tick_nohz_activate(struct tick_sched *ts, int mode)
@@ -1481,46 +1503,6 @@ void tick_irq_enter(void)
tick_nohz_irq_enter();
}
-/*
- * High resolution timer specific code
- */
-#ifdef CONFIG_HIGH_RES_TIMERS
-/*
- * We rearm the timer until we get disabled by the idle code.
- * Called with interrupts disabled.
- */
-static enum hrtimer_restart tick_nohz_highres_handler(struct hrtimer *timer)
-{
- struct tick_sched *ts =
- container_of(timer, struct tick_sched, sched_timer);
- struct pt_regs *regs = get_irq_regs();
- ktime_t now = ktime_get();
-
- tick_sched_do_timer(ts, now);
-
- /*
- * Do not call when we are not in IRQ context and have
- * no valid 'regs' pointer
- */
- if (regs)
- tick_sched_handle(ts, regs);
- else
- ts->next_tick = 0;
-
- /*
- * In dynticks mode, tick reprogram is deferred:
- * - to the idle task if in dynticks-idle
- * - to IRQ exit if in full-dynticks.
- */
- if (unlikely(ts->tick_stopped))
- return HRTIMER_NORESTART;
-
- hrtimer_forward(timer, now, TICK_NSEC);
-
- return HRTIMER_RESTART;
-}
-#endif /* HIGH_RES_TIMERS */
-
#if defined CONFIG_NO_HZ_COMMON || defined CONFIG_HIGH_RES_TIMERS
static int sched_skew_tick;
@@ -1542,10 +1524,8 @@ void tick_setup_sched_timer(int mode)
/* Emulate tick processing via per-CPU hrtimers: */
hrtimer_init(&ts->sched_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_HARD);
-#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());
--
2.34.1
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