Commit ac086bc2 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar

sched: rt-group: smp balancing

Currently the rt group scheduling does a per cpu runtime limit, however
the rt load balancer makes no guarantees about an equal spread of real-
time tasks, just that at any one time, the highest priority tasks run.

Solve this by making the runtime limit a global property by borrowing
excessive runtime from the other cpus once the local limit runs out.
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent d0b27fa7
...@@ -164,6 +164,7 @@ struct rt_prio_array { ...@@ -164,6 +164,7 @@ struct rt_prio_array {
struct rt_bandwidth { struct rt_bandwidth {
ktime_t rt_period; ktime_t rt_period;
u64 rt_runtime; u64 rt_runtime;
spinlock_t rt_runtime_lock;
struct hrtimer rt_period_timer; struct hrtimer rt_period_timer;
}; };
...@@ -198,6 +199,8 @@ void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime) ...@@ -198,6 +199,8 @@ void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime)
rt_b->rt_period = ns_to_ktime(period); rt_b->rt_period = ns_to_ktime(period);
rt_b->rt_runtime = runtime; rt_b->rt_runtime = runtime;
spin_lock_init(&rt_b->rt_runtime_lock);
hrtimer_init(&rt_b->rt_period_timer, hrtimer_init(&rt_b->rt_period_timer,
CLOCK_MONOTONIC, HRTIMER_MODE_REL); CLOCK_MONOTONIC, HRTIMER_MODE_REL);
rt_b->rt_period_timer.function = sched_rt_period_timer; rt_b->rt_period_timer.function = sched_rt_period_timer;
...@@ -414,6 +417,8 @@ struct rt_rq { ...@@ -414,6 +417,8 @@ struct rt_rq {
#endif #endif
int rt_throttled; int rt_throttled;
u64 rt_time; u64 rt_time;
u64 rt_runtime;
spinlock_t rt_runtime_lock;
#ifdef CONFIG_RT_GROUP_SCHED #ifdef CONFIG_RT_GROUP_SCHED
unsigned long rt_nr_boosted; unsigned long rt_nr_boosted;
...@@ -7299,6 +7304,8 @@ static void init_rt_rq(struct rt_rq *rt_rq, struct rq *rq) ...@@ -7299,6 +7304,8 @@ static void init_rt_rq(struct rt_rq *rt_rq, struct rq *rq)
rt_rq->rt_time = 0; rt_rq->rt_time = 0;
rt_rq->rt_throttled = 0; rt_rq->rt_throttled = 0;
rt_rq->rt_runtime = 0;
spin_lock_init(&rt_rq->rt_runtime_lock);
#ifdef CONFIG_RT_GROUP_SCHED #ifdef CONFIG_RT_GROUP_SCHED
rt_rq->rt_nr_boosted = 0; rt_rq->rt_nr_boosted = 0;
...@@ -7335,6 +7342,7 @@ static void init_tg_rt_entry(struct rq *rq, struct task_group *tg, ...@@ -7335,6 +7342,7 @@ static void init_tg_rt_entry(struct rq *rq, struct task_group *tg,
init_rt_rq(rt_rq, rq); init_rt_rq(rt_rq, rq);
rt_rq->tg = tg; rt_rq->tg = tg;
rt_rq->rt_se = rt_se; rt_rq->rt_se = rt_se;
rt_rq->rt_runtime = tg->rt_bandwidth.rt_runtime;
if (add) if (add)
list_add(&rt_rq->leaf_rt_rq_list, &rq->leaf_rt_rq_list); list_add(&rt_rq->leaf_rt_rq_list, &rq->leaf_rt_rq_list);
...@@ -7391,6 +7399,8 @@ void __init sched_init(void) ...@@ -7391,6 +7399,8 @@ void __init sched_init(void)
init_tg_rt_entry(rq, &init_task_group, init_tg_rt_entry(rq, &init_task_group,
&per_cpu(init_rt_rq, i), &per_cpu(init_rt_rq, i),
&per_cpu(init_sched_rt_entity, i), i, 1); &per_cpu(init_sched_rt_entity, i), i, 1);
#else
rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime;
#endif #endif
for (j = 0; j < CPU_LOAD_IDX_MAX; j++) for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
...@@ -7974,11 +7984,11 @@ static inline int tg_has_rt_tasks(struct task_group *tg) ...@@ -7974,11 +7984,11 @@ static inline int tg_has_rt_tasks(struct task_group *tg)
static int tg_set_bandwidth(struct task_group *tg, static int tg_set_bandwidth(struct task_group *tg,
u64 rt_period, u64 rt_runtime) u64 rt_period, u64 rt_runtime)
{ {
int err = 0; int i, err = 0;
mutex_lock(&rt_constraints_mutex); mutex_lock(&rt_constraints_mutex);
read_lock(&tasklist_lock); read_lock(&tasklist_lock);
if (rt_runtime_us == 0 && tg_has_rt_tasks(tg)) { if (rt_runtime == 0 && tg_has_rt_tasks(tg)) {
err = -EBUSY; err = -EBUSY;
goto unlock; goto unlock;
} }
...@@ -7986,8 +7996,19 @@ static int tg_set_bandwidth(struct task_group *tg, ...@@ -7986,8 +7996,19 @@ static int tg_set_bandwidth(struct task_group *tg,
err = -EINVAL; err = -EINVAL;
goto unlock; goto unlock;
} }
spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock);
tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period); tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period);
tg->rt_bandwidth.rt_runtime = rt_runtime; tg->rt_bandwidth.rt_runtime = rt_runtime;
for_each_possible_cpu(i) {
struct rt_rq *rt_rq = tg->rt_rq[i];
spin_lock(&rt_rq->rt_runtime_lock);
rt_rq->rt_runtime = rt_runtime;
spin_unlock(&rt_rq->rt_runtime_lock);
}
spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock);
unlock: unlock:
read_unlock(&tasklist_lock); read_unlock(&tasklist_lock);
mutex_unlock(&rt_constraints_mutex); mutex_unlock(&rt_constraints_mutex);
...@@ -8052,6 +8073,19 @@ static int sched_rt_global_constraints(void) ...@@ -8052,6 +8073,19 @@ static int sched_rt_global_constraints(void)
#else #else
static int sched_rt_global_constraints(void) static int sched_rt_global_constraints(void)
{ {
unsigned long flags;
int i;
spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
for_each_possible_cpu(i) {
struct rt_rq *rt_rq = &cpu_rq(i)->rt;
spin_lock(&rt_rq->rt_runtime_lock);
rt_rq->rt_runtime = global_rt_runtime();
spin_unlock(&rt_rq->rt_runtime_lock);
}
spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
return 0; return 0;
} }
#endif #endif
...@@ -8168,7 +8202,7 @@ static u64 cpu_shares_read_uint(struct cgroup *cgrp, struct cftype *cft) ...@@ -8168,7 +8202,7 @@ static u64 cpu_shares_read_uint(struct cgroup *cgrp, struct cftype *cft)
#endif #endif
#ifdef CONFIG_RT_GROUP_SCHED #ifdef CONFIG_RT_GROUP_SCHED
static int cpu_rt_runtime_write(struct cgroup *cgrp, struct cftype *cft, static ssize_t cpu_rt_runtime_write(struct cgroup *cgrp, struct cftype *cft,
struct file *file, struct file *file,
const char __user *userbuf, const char __user *userbuf,
size_t nbytes, loff_t *unused_ppos) size_t nbytes, loff_t *unused_ppos)
......
...@@ -62,7 +62,12 @@ static inline u64 sched_rt_runtime(struct rt_rq *rt_rq) ...@@ -62,7 +62,12 @@ static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
if (!rt_rq->tg) if (!rt_rq->tg)
return RUNTIME_INF; return RUNTIME_INF;
return rt_rq->tg->rt_bandwidth.rt_runtime; return rt_rq->rt_runtime;
}
static inline u64 sched_rt_period(struct rt_rq *rt_rq)
{
return ktime_to_ns(rt_rq->tg->rt_bandwidth.rt_period);
} }
#define for_each_leaf_rt_rq(rt_rq, rq) \ #define for_each_leaf_rt_rq(rt_rq, rq) \
...@@ -145,11 +150,21 @@ struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu) ...@@ -145,11 +150,21 @@ struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
return container_of(rt_b, struct task_group, rt_bandwidth)->rt_rq[cpu]; return container_of(rt_b, struct task_group, rt_bandwidth)->rt_rq[cpu];
} }
static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
{
return &rt_rq->tg->rt_bandwidth;
}
#else #else
static inline u64 sched_rt_runtime(struct rt_rq *rt_rq) static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
{ {
return def_rt_bandwidth.rt_runtime; return rt_rq->rt_runtime;
}
static inline u64 sched_rt_period(struct rt_rq *rt_rq)
{
return ktime_to_ns(def_rt_bandwidth.rt_period);
} }
#define for_each_leaf_rt_rq(rt_rq, rq) \ #define for_each_leaf_rt_rq(rt_rq, rq) \
...@@ -200,6 +215,11 @@ struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu) ...@@ -200,6 +215,11 @@ struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
return &cpu_rq(cpu)->rt; return &cpu_rq(cpu)->rt;
} }
static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
{
return &def_rt_bandwidth;
}
#endif #endif
static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun) static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
...@@ -218,8 +238,10 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun) ...@@ -218,8 +238,10 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
spin_lock(&rq->lock); spin_lock(&rq->lock);
if (rt_rq->rt_time) { if (rt_rq->rt_time) {
u64 runtime = rt_b->rt_runtime; u64 runtime;
spin_lock(&rt_rq->rt_runtime_lock);
runtime = rt_rq->rt_runtime;
rt_rq->rt_time -= min(rt_rq->rt_time, overrun*runtime); rt_rq->rt_time -= min(rt_rq->rt_time, overrun*runtime);
if (rt_rq->rt_throttled && rt_rq->rt_time < runtime) { if (rt_rq->rt_throttled && rt_rq->rt_time < runtime) {
rt_rq->rt_throttled = 0; rt_rq->rt_throttled = 0;
...@@ -227,6 +249,7 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun) ...@@ -227,6 +249,7 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
} }
if (rt_rq->rt_time || rt_rq->rt_nr_running) if (rt_rq->rt_time || rt_rq->rt_nr_running)
idle = 0; idle = 0;
spin_unlock(&rt_rq->rt_runtime_lock);
} }
if (enqueue) if (enqueue)
...@@ -237,6 +260,47 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun) ...@@ -237,6 +260,47 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
return idle; return idle;
} }
#ifdef CONFIG_SMP
static int balance_runtime(struct rt_rq *rt_rq)
{
struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
struct root_domain *rd = cpu_rq(smp_processor_id())->rd;
int i, weight, more = 0;
u64 rt_period;
weight = cpus_weight(rd->span);
spin_lock(&rt_b->rt_runtime_lock);
rt_period = ktime_to_ns(rt_b->rt_period);
for_each_cpu_mask(i, rd->span) {
struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
s64 diff;
if (iter == rt_rq)
continue;
spin_lock(&iter->rt_runtime_lock);
diff = iter->rt_runtime - iter->rt_time;
if (diff > 0) {
do_div(diff, weight);
if (rt_rq->rt_runtime + diff > rt_period)
diff = rt_period - rt_rq->rt_runtime;
iter->rt_runtime -= diff;
rt_rq->rt_runtime += diff;
more = 1;
if (rt_rq->rt_runtime == rt_period) {
spin_unlock(&iter->rt_runtime_lock);
break;
}
}
spin_unlock(&iter->rt_runtime_lock);
}
spin_unlock(&rt_b->rt_runtime_lock);
return more;
}
#endif
static inline int rt_se_prio(struct sched_rt_entity *rt_se) static inline int rt_se_prio(struct sched_rt_entity *rt_se)
{ {
#ifdef CONFIG_RT_GROUP_SCHED #ifdef CONFIG_RT_GROUP_SCHED
...@@ -259,6 +323,22 @@ static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq) ...@@ -259,6 +323,22 @@ static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
if (rt_rq->rt_throttled) if (rt_rq->rt_throttled)
return rt_rq_throttled(rt_rq); return rt_rq_throttled(rt_rq);
if (sched_rt_runtime(rt_rq) >= sched_rt_period(rt_rq))
return 0;
#ifdef CONFIG_SMP
if (rt_rq->rt_time > runtime) {
int more;
spin_unlock(&rt_rq->rt_runtime_lock);
more = balance_runtime(rt_rq);
spin_lock(&rt_rq->rt_runtime_lock);
if (more)
runtime = sched_rt_runtime(rt_rq);
}
#endif
if (rt_rq->rt_time > runtime) { if (rt_rq->rt_time > runtime) {
rt_rq->rt_throttled = 1; rt_rq->rt_throttled = 1;
if (rt_rq_throttled(rt_rq)) { if (rt_rq_throttled(rt_rq)) {
...@@ -294,9 +374,11 @@ static void update_curr_rt(struct rq *rq) ...@@ -294,9 +374,11 @@ static void update_curr_rt(struct rq *rq)
curr->se.exec_start = rq->clock; curr->se.exec_start = rq->clock;
cpuacct_charge(curr, delta_exec); cpuacct_charge(curr, delta_exec);
spin_lock(&rt_rq->rt_runtime_lock);
rt_rq->rt_time += delta_exec; rt_rq->rt_time += delta_exec;
if (sched_rt_runtime_exceeded(rt_rq)) if (sched_rt_runtime_exceeded(rt_rq))
resched_task(curr); resched_task(curr);
spin_unlock(&rt_rq->rt_runtime_lock);
} }
static inline static inline
......
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