sched: Normalize tg load contributions against runnable time
Entities of equal weight should receive equitable distribution of cpu time.
This is challenging in the case of a task_group's shares as execution may be
occurring on multiple cpus simultaneously.
To handle this we divide up the shares into weights proportionate with the load
on each cfs_rq. This does not however, account for the fact that the sum of
the parts may be less than one cpu and so we need to normalize:
load(tg) = min(runnable_avg(tg), 1) * tg->shares
Where runnable_avg is the aggregate time in which the task_group had runnable
children.
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/20120823141506.930124292@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 924a990..134928d 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -113,6 +113,7 @@
atomic_t load_weight;
atomic64_t load_avg;
+ atomic_t runnable_avg;
#endif
#ifdef CONFIG_RT_GROUP_SCHED
@@ -234,6 +235,7 @@
atomic64_t decay_counter, removed_load;
u64 last_decay;
#ifdef CONFIG_FAIR_GROUP_SCHED
+ u32 tg_runnable_contrib;
u64 tg_load_contrib;
#endif
#endif