Re: [PATCH] sched: put rq's sched_avg under CONFIG_FAIR_GROUP_SCHED

[Dietmar Eggemann <dietmar.eggemann@arm.com>]

On 25/02/14 20:52, Peter Zijlstra wrote:
> On Tue, Feb 25, 2014 at 11:47:42AM +0000, Dietmar Eggemann wrote:
>> +++ 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
>>  };
> 
> There is already a CONFIG_FAIR_GROUP_SCHED #ifdef in that structure;
> does it make sense to move this variable in there instead of adding yet
> another #ifdef?
> 

I changed the patch accordingly.

-- >8 --
Subject: [PATCH] sched: put rq's sched_avg under CONFIG_FAIR_GROUP_SCHED

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@arm.com>
---
 kernel/sched/fair.c  |   13 +++++++------
 kernel/sched/sched.h |    4 ++--
 2 files changed, 9 insertions(+), 8 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..b1fb1a62c52d 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -540,6 +540,8 @@ struct rq {
 #ifdef CONFIG_FAIR_GROUP_SCHED
 	/* list of leaf cfs_rq on this cpu: */
 	struct list_head leaf_cfs_rq_list;
+
+	struct sched_avg avg;
 #endif /* CONFIG_FAIR_GROUP_SCHED */
 
 	/*
@@ -629,8 +631,6 @@ struct rq {
 #ifdef CONFIG_SMP
 	struct llist_head wake_list;
 #endif
-
-	struct sched_avg avg;
 };
 
 static inline int cpu_of(struct rq *rq)
-- 
1.7.9.5