sched/fair: Propagate an effective runnable_load_avg

The load balancer uses runnable_load_avg as load indicator. For
!cgroup this is:

  runnable_load_avg = \Sum se->avg.load_avg ; where se->on_rq

That is, a direct sum of all runnable tasks on that runqueue. As
opposed to load_avg, which is a sum of all tasks on the runqueue,
which includes a blocked component.

However, in the cgroup case, this comes apart since the group entities
are always runnable, even if most of their constituent entities are
blocked.

Therefore introduce a runnable_weight which for task entities is the
same as the regular weight, but for group entities is a fraction of
the entity weight and represents the runnable part of the group
runqueue.

Then propagate this load through the PELT hierarchy to arrive at an
effective runnable load avgerage -- which we should not confuse with
the canonical runnable load average.

Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2017-05-06 15:59:54 +02:00 committed by Ingo Molnar
parent 0e2d2aaaae
commit 1ea6c46a23
4 changed files with 124 additions and 62 deletions

View file

@ -331,9 +331,11 @@ struct load_weight {
struct sched_avg {
u64 last_update_time;
u64 load_sum;
u64 runnable_load_sum;
u32 util_sum;
u32 period_contrib;
unsigned long load_avg;
unsigned long runnable_load_avg;
unsigned long util_avg;
};
@ -376,6 +378,7 @@ struct sched_statistics {
struct sched_entity {
/* For load-balancing: */
struct load_weight load;
unsigned long runnable_weight;
struct rb_node run_node;
struct list_head group_node;
unsigned int on_rq;