sched: Implement demand based update_cfs_load()

When the system is busy, dilation of rq->next_balance makes lb->update_shares()
insufficiently frequent for threads which don't sleep (no dequeue/enqueue
updates).  Adjust for this by making demand based updates based on the
accumulation of execution time sufficient to wrap our averaging window.

Signed-off-by: Paul Turner <pjt@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20101115234938.291159744@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 8 insertions, 1 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index dadab4d13875..e914a716e1d4 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -353,9 +353,16 @@ struct cfs_rq {
          */
         unsigned long h_load;
 
+        /*
+         * Maintaining per-cpu shares distribution for group scheduling
+         *
+         * load_stamp is the last time we updated the load average
+         * load_last is the last time we updated the load average and saw load
+         * load_unacc_exec_time is currently unaccounted execution time
+         */
         u64 load_avg;
         u64 load_period;
-        u64 load_stamp, load_last;
+        u64 load_stamp, load_last, load_unacc_exec_time;
 
         unsigned long load_contribution;
 #endif