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sched: Define sched_clock_irqtime as static key

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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: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20250103022409.2544-2-laoar.shao@gmail.com
This commit is contained in:
Yafang Shao 2025-01-03 10:24:06 +08:00 • committed by Peter Zijlstra
parent 3229adbe78
commit 8722903cbb
2 changed files with 20 additions and 9 deletions
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16
kernel/sched/cputime.c
View file

@ -9,6 +9,8 @@
#ifdef CONFIG_IRQ_TIME_ACCOUNTING #ifdef CONFIG_IRQ_TIME_ACCOUNTING
DEFINE_STATIC_KEY_FALSE(sched_clock_irqtime);
/* /*
* There are no locks covering percpu hardirq/softirq time. * There are no locks covering percpu hardirq/softirq time.
* They are only modified in vtime_account, on corresponding CPU * They are only modified in vtime_account, on corresponding CPU
@ -22,16 +24,14 @@
*/ */
DEFINE_PER_CPU(struct irqtime, cpu_irqtime); DEFINE_PER_CPU(struct irqtime, cpu_irqtime);
static int sched_clock_irqtime;
void enable_sched_clock_irqtime(void) void enable_sched_clock_irqtime(void)
{ {
sched_clock_irqtime = 1; static_branch_enable(&sched_clock_irqtime);
} }
void disable_sched_clock_irqtime(void) 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, 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; s64 delta;
int cpu; int cpu;
if (!sched_clock_irqtime) if (!irqtime_enabled())
return; return;
cpu = smp_processor_id(); cpu = smp_processor_id();
@ -90,8 +90,6 @@ static u64 irqtime_tick_accounted(u64 maxtime)
#else /* CONFIG_IRQ_TIME_ACCOUNTING */ #else /* CONFIG_IRQ_TIME_ACCOUNTING */
#define sched_clock_irqtime (0)
static u64 irqtime_tick_accounted(u64 dummy) static u64 irqtime_tick_accounted(u64 dummy)
{ {
return 0; return 0;
@ -478,7 +476,7 @@ void account_process_tick(struct task_struct *p, int user_tick)
if (vtime_accounting_enabled_this_cpu()) if (vtime_accounting_enabled_this_cpu())
return; return;
if (sched_clock_irqtime) { if (irqtime_enabled()) {
irqtime_account_process_tick(p, user_tick, 1); irqtime_account_process_tick(p, user_tick, 1);
return; return;
} }
@ -507,7 +505,7 @@ void account_idle_ticks(unsigned long ticks)
{ {
u64 cputime, steal; u64 cputime, steal;
if (sched_clock_irqtime) { if (irqtime_enabled()) {
irqtime_account_idle_ticks(ticks); irqtime_account_idle_ticks(ticks);
return; return;
} }

13
kernel/sched/sched.h
View file

@ -3233,6 +3233,12 @@ struct irqtime {
}; };
DECLARE_PER_CPU(struct irqtime, cpu_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. * Returns the irqtime minus the softirq time computed by ksoftirqd.
@ -3253,6 +3259,13 @@ static inline u64 irq_time_read(int cpu)
return total; return total;
} }
#else
static inline int irqtime_enabled(void)
{
return 0;
}
#endif /* CONFIG_IRQ_TIME_ACCOUNTING */ #endif /* CONFIG_IRQ_TIME_ACCOUNTING */
#ifdef CONFIG_CPU_FREQ #ifdef CONFIG_CPU_FREQ