path: root/kernel/sched/fair.c
diff options
authorPaul Turner <pjt@google.com>2012-10-04 13:18:32 +0200
committerIngo Molnar <mingo@kernel.org>2012-10-24 10:27:31 +0200
commitf4e26b120b9de84cb627bc7361ba43cfdc51341f (patch)
tree19786e34c5de3c9b7c9c871a27b0f8d85cc8690d /kernel/sched/fair.c
parent5b51f2f80b3b906ce59bd4dce6eca3c7f34cb1b9 (diff)
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>
Diffstat (limited to 'kernel/sched/fair.c')
1 files changed, 11 insertions, 2 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 6ecf455fd95..3e6a3531fa9 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)
-#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).
+ */
* 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 /* CONFIG_SMP */
static unsigned long
@@ -5773,8 +5781,9 @@ const struct sched_class fair_sched_class = {
.select_task_rq = select_task_rq_fair,
.migrate_task_rq = migrate_task_rq_fair,
.rq_online = rq_online_fair,
.rq_offline = rq_offline_fair,