Commit-ID: f4e26b120b9de84cb627bc7361ba43cfdc51341f
Gitweb: http://git.kernel.org/tip/f4e26b120b9de84cb627bc7361ba43cfdc51341f
Author: Paul Turner <pjt@xxxxxxxxxx>
AuthorDate: Thu, 4 Oct 2012 13:18:32 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 24 Oct 2012 10:27:31 +0200
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@xxxxxxxxxx>
Reviewed-by: Ben Segall <bsegall@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Link: http://lkml.kernel.org/r/20120823141507.422162369@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
include/linux/sched.h | 8 +++++++-
kernel/sched/core.c | 7 ++++++-
kernel/sched/fair.c | 13 +++++++++++--
kernel/sched/sched.h | 9 ++++++++-
4 files changed, 32 insertions(+), 5 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index e483ccb..e1581a0 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -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
};
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index f268600..5dae0d2 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -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
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 6ecf455..3e6a353 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -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.
@@ -3174,6 +3175,12 @@ unlock:
}
/*
+ * 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
* previous cpu. However, the caller only guarantees p->pi_lock is held; no
@@ -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,
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 0a75a43..5eca173 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -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;
--
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