sched: add tree based averages

add support for tree based vruntime averages.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

2 files changed, 18 insertions, 8 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index bf85b4b281c5..198b07a6d038 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -399,6 +399,8 @@ enum {
         SCHED_FEAT_SLEEPER_AVG          = 4,
         SCHED_FEAT_SLEEPER_LOAD_AVG     = 8,
         SCHED_FEAT_START_DEBIT          = 16,
+        SCHED_FEAT_USE_TREE_AVG         = 32,
+        SCHED_FEAT_APPROX_AVG           = 64,
 };
 
 const_debug unsigned int sysctl_sched_features =
@@ -406,7 +408,9 @@ const_debug unsigned int sysctl_sched_features =
                 SCHED_FEAT_NEW_FAIR_SLEEPERS    *1 |
                 SCHED_FEAT_SLEEPER_AVG          *0 |
                 SCHED_FEAT_SLEEPER_LOAD_AVG     *1 |
-                SCHED_FEAT_START_DEBIT          *1;
+                SCHED_FEAT_START_DEBIT          *1 |
+                SCHED_FEAT_USE_TREE_AVG         *0 |
+                SCHED_FEAT_APPROX_AVG           *0;
 
 #define sched_feat(x) (sysctl_sched_features & SCHED_FEAT_##x)
 
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index c8c6b0561391..86e5e8c5d101 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -547,16 +547,22 @@ static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
 static void
 place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
 {
-        struct sched_entity *last = __pick_last_entity(cfs_rq);
         u64 min_runtime, latency;
 
         min_runtime = cfs_rq->min_vruntime;
-        if (last) {
-                min_runtime += last->vruntime;
-                min_runtime >>= 1;
-                if (initial && sched_feat(START_DEBIT))
-                        min_runtime += sysctl_sched_latency/2;
-        }
+
+        if (sched_feat(USE_TREE_AVG)) {
+                struct sched_entity *last = __pick_last_entity(cfs_rq);
+                if (last) {
+                        min_runtime = __pick_next_entity(cfs_rq)->vruntime;
+                        min_runtime += last->vruntime;
+                        min_runtime >>= 1;
+                }
+        } else if (sched_feat(APPROX_AVG))
+                min_runtime += sysctl_sched_latency/2;
+
+        if (initial && sched_feat(START_DEBIT))
+                min_runtime += sched_slice(cfs_rq, se);
 
         if (!initial && sched_feat(NEW_FAIR_SLEEPERS)) {
                 latency = sysctl_sched_latency;