Commit 8722903c authored by Yafang Shao's avatar Yafang Shao Committed by Peter Zijlstra
Browse files

sched: Define sched_clock_irqtime as static key 



Since CPU time accounting is a performance-critical path, let's define
sched_clock_irqtime as a static key to minimize potential overhead.

Signed-off-by: default avatarYafang Shao <laoar.shao@gmail.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarMichal Koutný <mkoutny@suse.com>
Reviewed-by: default avatarVincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20250103022409.2544-2-laoar.shao@gmail.com
parent 3229adbe

kernel/sched/cputime.c

+7 −9
Original line number Diff line number Diff line
@@ -9,6 +9,8 @@ 


#ifdef CONFIG_IRQ_TIME_ACCOUNTING



DEFINE_STATIC_KEY_FALSE(sched_clock_irqtime);



/*

 * There are no locks covering percpu hardirq/softirq time.

 * They are only modified in vtime_account, on corresponding CPU
@@ -22,16 +24,14 @@ 
 */

DEFINE_PER_CPU(struct irqtime, cpu_irqtime);



static int sched_clock_irqtime;



void enable_sched_clock_irqtime(void)

{

	sched_clock_irqtime = 1;

	static_branch_enable(&sched_clock_irqtime);

}



void disable_sched_clock_irqtime(void)

{

	sched_clock_irqtime = 0;

	static_branch_disable(&sched_clock_irqtime);

}



static void irqtime_account_delta(struct irqtime *irqtime, u64 delta,
@@ -57,7 +57,7 @@ void irqtime_account_irq(struct task_struct *curr, unsigned int offset) 
	s64 delta;

	int cpu;



	if (!sched_clock_irqtime)

	if (!irqtime_enabled())

		return;



	cpu = smp_processor_id();
@@ -90,8 +90,6 @@ static u64 irqtime_tick_accounted(u64 maxtime) 


#else /* CONFIG_IRQ_TIME_ACCOUNTING */



#define sched_clock_irqtime	(0)



static u64 irqtime_tick_accounted(u64 dummy)

{

	return 0;
@@ -478,7 +476,7 @@ void account_process_tick(struct task_struct *p, int user_tick) 
	if (vtime_accounting_enabled_this_cpu())

		return;



	if (sched_clock_irqtime) {

	if (irqtime_enabled()) {

		irqtime_account_process_tick(p, user_tick, 1);

		return;

	}
@@ -507,7 +505,7 @@ void account_idle_ticks(unsigned long ticks) 
{

	u64 cputime, steal;



	if (sched_clock_irqtime) {

	if (irqtime_enabled()) {

		irqtime_account_idle_ticks(ticks);

		return;

	}

kernel/sched/sched.h

+13 −0
Original line number Diff line number Diff line
@@ -3233,6 +3233,12 @@ struct irqtime { 
};



DECLARE_PER_CPU(struct irqtime, cpu_irqtime);

DECLARE_STATIC_KEY_FALSE(sched_clock_irqtime);



static inline int irqtime_enabled(void)

{

	return static_branch_likely(&sched_clock_irqtime);

}



/*

 * Returns the irqtime minus the softirq time computed by ksoftirqd.
@@ -3253,6 +3259,13 @@ static inline u64 irq_time_read(int cpu) 
	return total;

}



#else



static inline int irqtime_enabled(void)

{

	return 0;

}



#endif /* CONFIG_IRQ_TIME_ACCOUNTING */



#ifdef CONFIG_CPU_FREQ