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sched: rt-group: smp balancing

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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: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra
2008-04-19 19:44:58 +02:00
committed by Ingo Molnar
parent d0b27fa778
commit ac086bc229
2 changed files with 122 additions and 6 deletions
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88
kernel/sched_rt.c
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@@ -62,7 +62,12 @@ static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
if (!rt_rq->tg)
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) \
@@ -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];
}
static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
{
return &rt_rq->tg->rt_bandwidth;
}
#else
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) \
@@ -200,6 +215,11 @@ struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
return &cpu_rq(cpu)->rt;
}
static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
{
return &def_rt_bandwidth;
}
#endif
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);
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);
if (rt_rq->rt_throttled && rt_rq->rt_time < runtime) {
rt_rq->rt_throttled = 0;
@@ -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)
idle = 0;
spin_unlock(&rt_rq->rt_runtime_lock);
}
if (enqueue)
@@ -237,6 +260,47 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
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)
{
#ifdef CONFIG_RT_GROUP_SCHED
@@ -259,6 +323,22 @@ static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
if (rt_rq->rt_throttled)
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) {
rt_rq->rt_throttled = 1;
if (rt_rq_throttled(rt_rq)) {
@@ -294,9 +374,11 @@ static void update_curr_rt(struct rq *rq)
curr->se.exec_start = rq->clock;
cpuacct_charge(curr, delta_exec);
spin_lock(&rt_rq->rt_runtime_lock);
rt_rq->rt_time += delta_exec;
if (sched_rt_runtime_exceeded(rt_rq))
resched_task(curr);
spin_unlock(&rt_rq->rt_runtime_lock);
}
static inline