Commit 953bfcd1 authored by Paul Turner's avatar Paul Turner Committed by Ingo Molnar
Browse files

sched: Implement hierarchical task accounting for SCHED_OTHER



Introduce hierarchical task accounting for the group scheduling case in CFS, as
well as promoting the responsibility for maintaining rq->nr_running to the
scheduling classes.

The primary motivation for this is that with scheduling classes supporting
bandwidth throttling it is possible for entities participating in throttled
sub-trees to not have root visible changes in rq->nr_running across activate
and de-activate operations.  This in turn leads to incorrect idle and
weight-per-task load balance decisions.

This also allows us to make a small fixlet to the fastpath in pick_next_task()
under group scheduling.

Note: this issue also exists with the existing sched_rt throttling mechanism.
This patch does not address that.
Signed-off-by: default avatarPaul Turner <pjt@google.com>
Reviewed-by: default avatarHidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20110721184756.878333391@google.com

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 5710f15b
......@@ -311,7 +311,7 @@ struct task_group root_task_group;
/* CFS-related fields in a runqueue */
struct cfs_rq {
struct load_weight load;
unsigned long nr_running;
unsigned long nr_running, h_nr_running;
u64 exec_clock;
u64 min_vruntime;
......@@ -1802,7 +1802,6 @@ static void activate_task(struct rq *rq, struct task_struct *p, int flags)
rq->nr_uninterruptible--;
enqueue_task(rq, p, flags);
inc_nr_running(rq);
}
/*
......@@ -1814,7 +1813,6 @@ static void deactivate_task(struct rq *rq, struct task_struct *p, int flags)
rq->nr_uninterruptible++;
dequeue_task(rq, p, flags);
dec_nr_running(rq);
}
#ifdef CONFIG_IRQ_TIME_ACCOUNTING
......@@ -4258,7 +4256,7 @@ pick_next_task(struct rq *rq)
* Optimization: we know that if all tasks are in
* the fair class we can call that function directly:
*/
if (likely(rq->nr_running == rq->cfs.nr_running)) {
if (likely(rq->nr_running == rq->cfs.h_nr_running)) {
p = fair_sched_class.pick_next_task(rq);
if (likely(p))
return p;
......
......@@ -1310,16 +1310,19 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
break;
cfs_rq = cfs_rq_of(se);
enqueue_entity(cfs_rq, se, flags);
cfs_rq->h_nr_running++;
flags = ENQUEUE_WAKEUP;
}
for_each_sched_entity(se) {
cfs_rq = cfs_rq_of(se);
cfs_rq->h_nr_running++;
update_cfs_load(cfs_rq, 0);
update_cfs_shares(cfs_rq);
}
inc_nr_running(rq);
hrtick_update(rq);
}
......@@ -1339,6 +1342,7 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
for_each_sched_entity(se) {
cfs_rq = cfs_rq_of(se);
dequeue_entity(cfs_rq, se, flags);
cfs_rq->h_nr_running--;
/* Don't dequeue parent if it has other entities besides us */
if (cfs_rq->load.weight) {
......@@ -1358,11 +1362,13 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
for_each_sched_entity(se) {
cfs_rq = cfs_rq_of(se);
cfs_rq->h_nr_running--;
update_cfs_load(cfs_rq, 0);
update_cfs_shares(cfs_rq);
}
dec_nr_running(rq);
hrtick_update(rq);
}
......
......@@ -936,6 +936,8 @@ enqueue_task_rt(struct rq *rq, struct task_struct *p, int flags)
if (!task_current(rq, p) && p->rt.nr_cpus_allowed > 1)
enqueue_pushable_task(rq, p);
inc_nr_running(rq);
}
static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags)
......@@ -946,6 +948,8 @@ static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags)
dequeue_rt_entity(rt_se);
dequeue_pushable_task(rq, p);
dec_nr_running(rq);
}
/*
......@@ -1841,4 +1845,3 @@ static void print_rt_stats(struct seq_file *m, int cpu)
rcu_read_unlock();
}
#endif /* CONFIG_SCHED_DEBUG */
......@@ -34,11 +34,13 @@ static struct task_struct *pick_next_task_stop(struct rq *rq)
static void
enqueue_task_stop(struct rq *rq, struct task_struct *p, int flags)
{
inc_nr_running(rq);
}
static void
dequeue_task_stop(struct rq *rq, struct task_struct *p, int flags)
{
dec_nr_running(rq);
}
static void yield_task_stop(struct rq *rq)
......
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