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sched: rt throttling vs no_hz

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We need to teach no_hz about the rt throttling because its tick driven.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2008-01-25 21:08:31 +01:00 committed by Ingo Molnar
parent 614ee1f61f
commit 48d5e25821
4 changed files with 45 additions and 15 deletions
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2
include/linux/sched.h
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@ -230,6 +230,8 @@ static inline int select_nohz_load_balancer(int cpu)
}
#endif
extern unsigned long rt_needs_cpu(int cpu);
/*
* Only dump TASK_* tasks. (0 for all tasks)
*/

23
kernel/sched.c
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@ -442,6 +442,7 @@ struct rq {
struct cfs_rq cfs;
struct rt_rq rt;
u64 rt_period_expire;
int rt_throttled;
#ifdef CONFIG_FAIR_GROUP_SCHED
/* list of leaf cfs_rq on this cpu: */
@ -594,6 +595,23 @@ static void update_rq_clock(struct rq *rq)
#define task_rq(p) cpu_rq(task_cpu(p))
#define cpu_curr(cpu) (cpu_rq(cpu)->curr)
unsigned long rt_needs_cpu(int cpu)
{
struct rq *rq = cpu_rq(cpu);
u64 delta;
if (!rq->rt_throttled)
return 0;
if (rq->clock > rq->rt_period_expire)
return 1;
delta = rq->rt_period_expire - rq->clock;
do_div(delta, NSEC_PER_SEC / HZ);
return (unsigned long)delta;
}
/*
* Tunables that become constants when CONFIG_SCHED_DEBUG is off:
*/
@ -7102,9 +7120,11 @@ static void init_rt_rq(struct rt_rq *rt_rq, struct rq *rq)
/* delimiter for bitsearch: */
__set_bit(MAX_RT_PRIO, array->bitmap);
#if defined CONFIG_SMP || defined CONFIG_FAIR_GROUP_SCHED
rt_rq->highest_prio = MAX_RT_PRIO;
#endif
#ifdef CONFIG_SMP
rt_rq->rt_nr_migratory = 0;
rt_rq->highest_prio = MAX_RT_PRIO;
rt_rq->overloaded = 0;
#endif
@ -7191,6 +7211,7 @@ void __init sched_init(void)
&per_cpu(init_sched_rt_entity, i), i, 1);
#endif
rq->rt_period_expire = 0;
rq->rt_throttled = 0;
for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
rq->cpu_load[j] = 0;

30
kernel/sched_rt.c
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@ -175,7 +175,11 @@ static int sched_rt_ratio_exceeded(struct rt_rq *rt_rq)
ratio = (period * rt_ratio) >> SCHED_RT_FRAC_SHIFT;
if (rt_rq->rt_time > ratio) {
struct rq *rq = rq_of_rt_rq(rt_rq);
rq->rt_throttled = 1;
rt_rq->rt_throttled = 1;
sched_rt_ratio_dequeue(rt_rq);
return 1;
}
@ -183,18 +187,6 @@ static int sched_rt_ratio_exceeded(struct rt_rq *rt_rq)
return 0;
}
static void __update_sched_rt_period(struct rt_rq *rt_rq, u64 period)
{
unsigned long rt_ratio = sched_rt_ratio(rt_rq);
u64 ratio = (period * rt_ratio) >> SCHED_RT_FRAC_SHIFT;
rt_rq->rt_time -= min(rt_rq->rt_time, ratio);
if (rt_rq->rt_throttled) {
rt_rq->rt_throttled = 0;
sched_rt_ratio_enqueue(rt_rq);
}
}
static void update_sched_rt_period(struct rq *rq)
{
struct rt_rq *rt_rq;
@ -204,8 +196,18 @@ static void update_sched_rt_period(struct rq *rq)
period = (u64)sysctl_sched_rt_period * NSEC_PER_MSEC;
rq->rt_period_expire += period;
for_each_leaf_rt_rq(rt_rq, rq)
__update_sched_rt_period(rt_rq, period);
for_each_leaf_rt_rq(rt_rq, rq) {
unsigned long rt_ratio = sched_rt_ratio(rt_rq);
u64 ratio = (period * rt_ratio) >> SCHED_RT_FRAC_SHIFT;
rt_rq->rt_time -= min(rt_rq->rt_time, ratio);
if (rt_rq->rt_throttled) {
rt_rq->rt_throttled = 0;
sched_rt_ratio_enqueue(rt_rq);
}
}
rq->rt_throttled = 0;
}
}

5
kernel/time/tick-sched.c
View File

@ -153,6 +153,7 @@ void tick_nohz_update_jiffies(void)
void tick_nohz_stop_sched_tick(void)
{
unsigned long seq, last_jiffies, next_jiffies, delta_jiffies, flags;
unsigned long rt_jiffies;
struct tick_sched *ts;
ktime_t last_update, expires, now, delta;
struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev;
@ -216,6 +217,10 @@ void tick_nohz_stop_sched_tick(void)
next_jiffies = get_next_timer_interrupt(last_jiffies);
delta_jiffies = next_jiffies - last_jiffies;
rt_jiffies = rt_needs_cpu(cpu);
if (rt_jiffies && rt_jiffies < delta_jiffies)
delta_jiffies = rt_jiffies;
if (rcu_needs_cpu(cpu))
delta_jiffies = 1;
/*