linux-kernel - [PATCH] sched: put rq's sched_avg under CONFIG_FAIR_GROUP

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Date:	Tue, 25 Feb 2014 11:47:42 +0000
From:	Dietmar Eggemann <dietmar.eggemann@....com>
To:	Peter Zijlstra <peterz@...radead.org>,
	Ben Segall <bsegall@...gle.com>
Cc:	linux-kernel@...r.kernel.org,
	Dietmar Eggemann <dietmar.eggemann@....com>
Subject: [PATCH] sched: put rq's sched_avg under CONFIG_FAIR_GROUP_SCHED

From: Dietmar Eggemann <Dietmar.Eggemann@....com>

The struct sched_avg of struct rq is only used in case group
scheduling is enabled inside __update_tg_runnable_avg() to update
per-cpu representation of a task group.  I.e. that there is no need to
maintain the runnable avg of a rq in the !CONFIG_FAIR_GROUP_SCHED case.

This patch guards struct sched_avg of struct rq and
update_rq_runnable_avg() with CONFIG_FAIR_GROUP_SCHED.

There is an extra empty definition for update_rq_runnable_avg()
necessary for the !CONFIG_FAIR_GROUP_SCHED && CONFIG_SMP case.

The function print_cfs_group_stats() which prints out struct sched_avg
of struct rq is already guarded with CONFIG_FAIR_GROUP_SCHED.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@....com>
---

Hi,

I was just wondering what the overall policy is when it comes to guard
specific functionality in the scheduler code?  Do we want to to guard
something like the fair group scheduling support completely?

The patch is against tip/master .

 kernel/sched/fair.c  |   13 +++++++------
 kernel/sched/sched.h |    2 ++
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 5f6ddbef80af..76c6513b6889 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2376,12 +2376,19 @@ static inline void __update_group_entity_contrib(struct sched_entity *se)
 		se->avg.load_avg_contrib >>= NICE_0_SHIFT;
 	}
 }
+
+static inline void update_rq_runnable_avg(struct rq *rq, int runnable)
+{
+	__update_entity_runnable_avg(rq_clock_task(rq), &rq->avg, runnable);
+	__update_tg_runnable_avg(&rq->avg, &rq->cfs);
+}
 #else /* CONFIG_FAIR_GROUP_SCHED */
 static inline void __update_cfs_rq_tg_load_contrib(struct cfs_rq *cfs_rq,
 						 int force_update) {}
 static inline void __update_tg_runnable_avg(struct sched_avg *sa,
 						  struct cfs_rq *cfs_rq) {}
 static inline void __update_group_entity_contrib(struct sched_entity *se) {}
+static inline void update_rq_runnable_avg(struct rq *rq, int runnable) {}
 #endif /* CONFIG_FAIR_GROUP_SCHED */
 
 static inline void __update_task_entity_contrib(struct sched_entity *se)
@@ -2480,12 +2487,6 @@ static void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq, int force_update)
 	__update_cfs_rq_tg_load_contrib(cfs_rq, force_update);
 }
 
-static inline void update_rq_runnable_avg(struct rq *rq, int runnable)
-{
-	__update_entity_runnable_avg(rq_clock_task(rq), &rq->avg, runnable);
-	__update_tg_runnable_avg(&rq->avg, &rq->cfs);
-}
-
 /* Add the load generated by se into cfs_rq's child load-average */
 static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq,
 						  struct sched_entity *se,
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 4be68da1fe00..63beab7512e7 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -630,7 +630,9 @@ struct rq {
 	struct llist_head wake_list;
 #endif
 
+#ifdef CONFIG_FAIR_GROUP_SCHED
 	struct sched_avg avg;
+#endif
 };
 
 static inline int cpu_of(struct rq *rq)
-- 
1.7.9.5


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