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sched: Introduce temporary FAIR_GROUP_SCHED dependency for load-tracking 

While per-entity load-tracking is generally useful, beyond computing shares
distribution, e.g. runnable based load-balance (in progress), governors,
power-management, etc.

These facilities are not yet consumers of this data.  This may be trivially
reverted when the information is required; but avoid paying the overhead for
calculations we will not use until then.

Signed-off-by: Paul Turner <pjt@google.com>
Reviewed-by: Ben Segall <bsegall@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20120823141507.422162369@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Paul Turner 2012-10-04 13:18:32 +02:00 committed by Ingo Molnar
parent 5b51f2f80b
commit f4e26b120b
4 changed files with 32 additions and 5 deletions
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8
include/linux/sched.h
View File

@ -1168,7 +1168,13 @@ struct sched_entity {
/* rq "owned" by this entity/group: */
struct cfs_rq *my_q;
#endif
#ifdef CONFIG_SMP
/*
* Load-tracking only depends on SMP, FAIR_GROUP_SCHED dependency below may be
* removed when useful for applications beyond shares distribution (e.g.
* load-balance).
*/
#if defined(CONFIG_SMP) && defined(CONFIG_FAIR_GROUP_SCHED)
/* Per-entity load-tracking */
struct sched_avg avg;
#endif
};

7
kernel/sched/core.c
View File

@ -1526,7 +1526,12 @@ static void __sched_fork(struct task_struct *p)
p->se.vruntime = 0;
INIT_LIST_HEAD(&p->se.group_node);
#ifdef CONFIG_SMP
/*
* Load-tracking only depends on SMP, FAIR_GROUP_SCHED dependency below may be
* removed when useful for applications beyond shares distribution (e.g.
* load-balance).
*/
#if defined(CONFIG_SMP) && defined(CONFIG_FAIR_GROUP_SCHED)
p->se.avg.runnable_avg_period = 0;
p->se.avg.runnable_avg_sum = 0;
#endif

13
kernel/sched/fair.c
View File

@ -882,7 +882,8 @@ static inline void update_cfs_shares(struct cfs_rq *cfs_rq)
}
#endif /* CONFIG_FAIR_GROUP_SCHED */
#ifdef CONFIG_SMP
/* Only depends on SMP, FAIR_GROUP_SCHED may be removed when useful in lb */
#if defined(CONFIG_SMP) && defined(CONFIG_FAIR_GROUP_SCHED)
/*
* We choose a half-life close to 1 scheduling period.
* Note: The tables below are dependent on this value.
@ -3173,6 +3174,12 @@ select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flags)
return new_cpu;
}
/*
* Load-tracking only depends on SMP, FAIR_GROUP_SCHED dependency below may be
* removed when useful for applications beyond shares distribution (e.g.
* load-balance).
*/
#ifdef CONFIG_FAIR_GROUP_SCHED
/*
* Called immediately before a task is migrated to a new cpu; task_cpu(p) and
* cfs_rq_of(p) references at time of call are still valid and identify the
@ -3196,6 +3203,7 @@ migrate_task_rq_fair(struct task_struct *p, int next_cpu)
atomic64_add(se->avg.load_avg_contrib, &cfs_rq->removed_load);
}
}
#endif
#endif /* CONFIG_SMP */
static unsigned long
@ -5773,8 +5781,9 @@ const struct sched_class fair_sched_class = {
#ifdef CONFIG_SMP
.select_task_rq = select_task_rq_fair,
#ifdef CONFIG_FAIR_GROUP_SCHED
.migrate_task_rq = migrate_task_rq_fair,
#endif
.rq_online = rq_online_fair,
.rq_offline = rq_offline_fair,

9
kernel/sched/sched.h
View File

@ -225,6 +225,12 @@ struct cfs_rq {
#endif
#ifdef CONFIG_SMP
/*
* Load-tracking only depends on SMP, FAIR_GROUP_SCHED dependency below may be
* removed when useful for applications beyond shares distribution (e.g.
* load-balance).
*/
#ifdef CONFIG_FAIR_GROUP_SCHED
/*
* CFS Load tracking
* Under CFS, load is tracked on a per-entity basis and aggregated up.
@ -234,7 +240,8 @@ struct cfs_rq {
u64 runnable_load_avg, blocked_load_avg;
atomic64_t decay_counter, removed_load;
u64 last_decay;
#endif /* CONFIG_FAIR_GROUP_SCHED */
/* These always depend on CONFIG_FAIR_GROUP_SCHED */
#ifdef CONFIG_FAIR_GROUP_SCHED
u32 tg_runnable_contrib;
u64 tg_load_contrib;