sched: Compute load contribution by a group entity

Unlike task entities who have a fixed weight, group entities instead own a
fraction of their parenting task_group's shares as their contributed weight.

Compute this fraction so that we can correctly account hierarchies and shared
entity nodes.

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/20120823141506.855074415@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 27 insertions, 6 deletions

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index db788222f19..e20cb2693ef 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1117,22 +1117,43 @@ static inline void __update_cfs_rq_tg_load_contrib(struct cfs_rq *cfs_rq,
                 cfs_rq->tg_load_contrib += tg_contrib;
         }
 }
+
+static inline void __update_group_entity_contrib(struct sched_entity *se)
+{
+        struct cfs_rq *cfs_rq = group_cfs_rq(se);
+        struct task_group *tg = cfs_rq->tg;
+        u64 contrib;
+
+        contrib = cfs_rq->tg_load_contrib * tg->shares;
+        se->avg.load_avg_contrib = div64_u64(contrib,
+                                             atomic64_read(&tg->load_avg) + 1);
+}
 #else
 static inline void __update_cfs_rq_tg_load_contrib(struct cfs_rq *cfs_rq,
                                                  int force_update) {}
+static inline void __update_group_entity_contrib(struct sched_entity *se) {}
 #endif
 
+static inline void __update_task_entity_contrib(struct sched_entity *se)
+{
+        u32 contrib;
+
+        /* avoid overflowing a 32-bit type w/ SCHED_LOAD_SCALE */
+        contrib = se->avg.runnable_avg_sum * scale_load_down(se->load.weight);
+        contrib /= (se->avg.runnable_avg_period + 1);
+        se->avg.load_avg_contrib = scale_load(contrib);
+}
+
 /* Compute the current contribution to load_avg by se, return any delta */
 static long __update_entity_load_avg_contrib(struct sched_entity *se)
 {
         long old_contrib = se->avg.load_avg_contrib;
 
-        if (!entity_is_task(se))
-                return 0;
-
-        se->avg.load_avg_contrib = div64_u64(se->avg.runnable_avg_sum *
-                                             se->load.weight,
-                                             se->avg.runnable_avg_period + 1);
+        if (entity_is_task(se)) {
+                __update_task_entity_contrib(se);
+        } else {
+                __update_group_entity_contrib(se);
+        }
 
         return se->avg.load_avg_contrib - old_contrib;
 }