提交 6378ddb5 编写于 作者: V Venki Pallipadi 提交者: Ingo Molnar

time: track accurate idle time with tick_sched.idle_sleeptime

Current idle time in kstat is based on jiffies and is coarse grained.
tick_sched.idle_sleeptime is making some attempt to keep track of idle time
in a fine grained manner.  But, it is not handling the time spent in
interrupts fully.

Make tick_sched.idle_sleeptime accurate with respect to time spent on
handling interrupts and also add tick_sched.idle_lastupdate, which keeps
track of last time when idle_sleeptime was updated.

This statistics will be crucial for cpufreq-ondemand governor, which can
shed some conservative gaurd band that is uses today while setting the
frequency.  The ondemand changes that uses the exact idle time is coming
soon.
Signed-off-by: NVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
上级 bbe4d18a
...@@ -51,8 +51,10 @@ struct tick_sched { ...@@ -51,8 +51,10 @@ struct tick_sched {
unsigned long idle_jiffies; unsigned long idle_jiffies;
unsigned long idle_calls; unsigned long idle_calls;
unsigned long idle_sleeps; unsigned long idle_sleeps;
int idle_active;
ktime_t idle_entrytime; ktime_t idle_entrytime;
ktime_t idle_sleeptime; ktime_t idle_sleeptime;
ktime_t idle_lastupdate;
ktime_t sleep_length; ktime_t sleep_length;
unsigned long last_jiffies; unsigned long last_jiffies;
unsigned long next_jiffies; unsigned long next_jiffies;
...@@ -103,6 +105,8 @@ extern void tick_nohz_stop_sched_tick(void); ...@@ -103,6 +105,8 @@ extern void tick_nohz_stop_sched_tick(void);
extern void tick_nohz_restart_sched_tick(void); extern void tick_nohz_restart_sched_tick(void);
extern void tick_nohz_update_jiffies(void); extern void tick_nohz_update_jiffies(void);
extern ktime_t tick_nohz_get_sleep_length(void); extern ktime_t tick_nohz_get_sleep_length(void);
extern void tick_nohz_stop_idle(int cpu);
extern u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time);
# else # else
static inline void tick_nohz_stop_sched_tick(void) { } static inline void tick_nohz_stop_sched_tick(void) { }
static inline void tick_nohz_restart_sched_tick(void) { } static inline void tick_nohz_restart_sched_tick(void) { }
...@@ -113,6 +117,8 @@ static inline ktime_t tick_nohz_get_sleep_length(void) ...@@ -113,6 +117,8 @@ static inline ktime_t tick_nohz_get_sleep_length(void)
return len; return len;
} }
static inline void tick_nohz_stop_idle(int cpu) { }
static inline u64 get_cpu_idle_time_us(int cpu, u64 *unused) { return 0; }
# endif /* !NO_HZ */ # endif /* !NO_HZ */
#endif #endif
...@@ -280,9 +280,14 @@ asmlinkage void do_softirq(void) ...@@ -280,9 +280,14 @@ asmlinkage void do_softirq(void)
*/ */
void irq_enter(void) void irq_enter(void)
{ {
#ifdef CONFIG_NO_HZ
int cpu = smp_processor_id();
if (idle_cpu(cpu) && !in_interrupt())
tick_nohz_stop_idle(cpu);
#endif
__irq_enter(); __irq_enter();
#ifdef CONFIG_NO_HZ #ifdef CONFIG_NO_HZ
if (idle_cpu(smp_processor_id())) if (idle_cpu(cpu))
tick_nohz_update_jiffies(); tick_nohz_update_jiffies();
#endif #endif
} }
......
...@@ -143,6 +143,44 @@ void tick_nohz_update_jiffies(void) ...@@ -143,6 +143,44 @@ void tick_nohz_update_jiffies(void)
local_irq_restore(flags); local_irq_restore(flags);
} }
void tick_nohz_stop_idle(int cpu)
{
struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
if (ts->idle_active) {
ktime_t now, delta;
now = ktime_get();
delta = ktime_sub(now, ts->idle_entrytime);
ts->idle_lastupdate = now;
ts->idle_sleeptime = ktime_add(ts->idle_sleeptime, delta);
ts->idle_active = 0;
}
}
static ktime_t tick_nohz_start_idle(int cpu)
{
struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
ktime_t now, delta;
now = ktime_get();
if (ts->idle_active) {
delta = ktime_sub(now, ts->idle_entrytime);
ts->idle_lastupdate = now;
ts->idle_sleeptime = ktime_add(ts->idle_sleeptime, delta);
}
ts->idle_entrytime = now;
ts->idle_active = 1;
return now;
}
u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time)
{
struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
*last_update_time = ktime_to_us(ts->idle_lastupdate);
return ktime_to_us(ts->idle_sleeptime);
}
/** /**
* tick_nohz_stop_sched_tick - stop the idle tick from the idle task * tick_nohz_stop_sched_tick - stop the idle tick from the idle task
* *
...@@ -155,13 +193,14 @@ void tick_nohz_stop_sched_tick(void) ...@@ -155,13 +193,14 @@ void tick_nohz_stop_sched_tick(void)
unsigned long seq, last_jiffies, next_jiffies, delta_jiffies, flags; unsigned long seq, last_jiffies, next_jiffies, delta_jiffies, flags;
unsigned long rt_jiffies; unsigned long rt_jiffies;
struct tick_sched *ts; struct tick_sched *ts;
ktime_t last_update, expires, now, delta; ktime_t last_update, expires, now;
struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev; struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev;
int cpu; int cpu;
local_irq_save(flags); local_irq_save(flags);
cpu = smp_processor_id(); cpu = smp_processor_id();
now = tick_nohz_start_idle(cpu);
ts = &per_cpu(tick_cpu_sched, cpu); ts = &per_cpu(tick_cpu_sched, cpu);
/* /*
...@@ -193,19 +232,7 @@ void tick_nohz_stop_sched_tick(void) ...@@ -193,19 +232,7 @@ void tick_nohz_stop_sched_tick(void)
} }
} }
now = ktime_get();
/*
* When called from irq_exit we need to account the idle sleep time
* correctly.
*/
if (ts->tick_stopped) {
delta = ktime_sub(now, ts->idle_entrytime);
ts->idle_sleeptime = ktime_add(ts->idle_sleeptime, delta);
}
ts->idle_entrytime = now;
ts->idle_calls++; ts->idle_calls++;
/* Read jiffies and the time when jiffies were updated last */ /* Read jiffies and the time when jiffies were updated last */
do { do {
seq = read_seqbegin(&xtime_lock); seq = read_seqbegin(&xtime_lock);
...@@ -337,23 +364,22 @@ void tick_nohz_restart_sched_tick(void) ...@@ -337,23 +364,22 @@ void tick_nohz_restart_sched_tick(void)
int cpu = smp_processor_id(); int cpu = smp_processor_id();
struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
unsigned long ticks; unsigned long ticks;
ktime_t now, delta; ktime_t now;
if (!ts->tick_stopped) local_irq_disable();
tick_nohz_stop_idle(cpu);
if (!ts->tick_stopped) {
local_irq_enable();
return; return;
}
/* Update jiffies first */ /* Update jiffies first */
now = ktime_get();
local_irq_disable();
select_nohz_load_balancer(0); select_nohz_load_balancer(0);
now = ktime_get();
tick_do_update_jiffies64(now); tick_do_update_jiffies64(now);
cpu_clear(cpu, nohz_cpu_mask); cpu_clear(cpu, nohz_cpu_mask);
/* Account the idle time */
delta = ktime_sub(now, ts->idle_entrytime);
ts->idle_sleeptime = ktime_add(ts->idle_sleeptime, delta);
/* /*
* We stopped the tick in idle. Update process times would miss the * We stopped the tick in idle. Update process times would miss the
* time we slept as update_process_times does only a 1 tick * time we slept as update_process_times does only a 1 tick
......
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