sched: Move periodic share updates to entity_tick()

Long running entities that do not block (dequeue) require periodic updates to
maintain accurate share values.  (Note: group entities with several threads are
quite likely to be non-blocking in many circumstances).

By virtue of being long-running however, we will see entity ticks (otherwise
the required update occurs in dequeue/put and we are done).  Thus we can move
the detection (and associated work) for these updates into the periodic path.

This restores the 'atomicity' of update_curr() with respect to accounting.

Signed-off-by: Paul Turner <pjt@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20101216031038.067028969@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 17 insertions, 4 deletions

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index c88671718bc9..16ee398d8a4e 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -564,10 +564,6 @@ __update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr,
 
 #if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED
         cfs_rq->load_unacc_exec_time += delta_exec;
-        if (cfs_rq->load_unacc_exec_time > sysctl_sched_shares_window) {
-                update_cfs_load(cfs_rq, 0);
-                update_cfs_shares(cfs_rq, 0);
-        }
 #endif
 }
 
@@ -809,6 +805,14 @@ static void update_cfs_shares(struct cfs_rq *cfs_rq, long weight_delta)
 
         reweight_entity(cfs_rq_of(se), se, shares);
 }
+
+static void update_entity_shares_tick(struct cfs_rq *cfs_rq)
+{
+        if (cfs_rq->load_unacc_exec_time > sysctl_sched_shares_window) {
+                update_cfs_load(cfs_rq, 0);
+                update_cfs_shares(cfs_rq, 0);
+        }
+}
 #else /* CONFIG_FAIR_GROUP_SCHED */
 static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update)
 {
@@ -817,6 +821,10 @@ static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update)
 static inline void update_cfs_shares(struct cfs_rq *cfs_rq, long weight_delta)
 {
 }
+
+static inline void update_entity_shares_tick(struct cfs_rq *cfs_rq)
+{
+}
 #endif /* CONFIG_FAIR_GROUP_SCHED */
 
 static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
@@ -1133,6 +1141,11 @@ entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
          */
         update_curr(cfs_rq);
 
+        /*
+         * Update share accounting for long-running entities.
+         */
+        update_entity_shares_tick(cfs_rq);
+
 #ifdef CONFIG_SCHED_HRTICK
         /*
          * queued ticks are scheduled to match the slice, so don't bother