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| author | Morten Rasmussen <morten.rasmussen@arm.com> | 2018-07-04 11:17:40 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2018-09-10 11:05:49 +0200 |
| commit | 3b1baa6496e6b7ad016342a9d256bdfb072ce902 (patch) | |
| tree | 9e91be8d2548ed6113f0e69636c5e22766d0b8c5 /kernel/sched/sched.h | |
| parent | df054e8445a4011e3d693c2268129c0456108663 (diff) | |
| download | lwn-3b1baa6496e6b7ad016342a9d256bdfb072ce902.tar.gz lwn-3b1baa6496e6b7ad016342a9d256bdfb072ce902.zip | |
sched/fair: Add 'group_misfit_task' load-balance type
To maximize throughput in systems with asymmetric CPU capacities (e.g.
ARM big.LITTLE) load-balancing has to consider task and CPU utilization
as well as per-CPU compute capacity when load-balancing in addition to
the current average load based load-balancing policy. Tasks with high
utilization that are scheduled on a lower capacity CPU need to be
identified and migrated to a higher capacity CPU if possible to maximize
throughput.
To implement this additional policy an additional group_type
(load-balance scenario) is added: 'group_misfit_task'. This represents
scenarios where a sched_group has one or more tasks that are not
suitable for its per-CPU capacity. 'group_misfit_task' is only considered
if the system is not overloaded or imbalanced ('group_imbalanced' or
'group_overloaded').
Identifying misfit tasks requires the rq lock to be held. To avoid
taking remote rq locks to examine source sched_groups for misfit tasks,
each CPU is responsible for tracking misfit tasks themselves and update
the rq->misfit_task flag. This means checking task utilization when
tasks are scheduled and on sched_tick.
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
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: dietmar.eggemann@arm.com
Cc: gaku.inami.xh@renesas.com
Cc: valentin.schneider@arm.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1530699470-29808-3-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched/sched.h')
| -rw-r--r-- | kernel/sched/sched.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 0f36adc31ba5..7dbf67d147a2 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -842,6 +842,8 @@ struct rq { unsigned char idle_balance; + unsigned long misfit_task_load; + /* For active balancing */ int active_balance; int push_cpu; |