diff options
| author | Morten Rasmussen <morten.rasmussen@arm.com> | 2016-10-14 14:41:10 +0100 |
|---|---|---|
| committer | Andres Oportus <andresoportus@google.com> | 2017-06-02 08:01:52 -0700 |
| commit | adc7f08b2fb617a7b1c30e9dd87e36dcfbe9facb (patch) | |
| tree | 5e96f3eb302746e821f7c1c744cbfd8619937bcd /kernel | |
| parent | 60cc9f4e1e9fa3e951fb5a04d420da6eeb3067ee (diff) | |
UPSTREAM: sched/fair: Avoid pulling tasks from non-overloaded higher capacity groups
For asymmetric CPU capacity systems it is counter-productive for
throughput if low capacity CPUs are pulling tasks from non-overloaded
CPUs with higher capacity. The assumption is that higher CPU capacity is
preferred over running alone in a group with lower CPU capacity.
This patch rejects higher CPU capacity groups with one or less task per
CPU as potential busiest group which could otherwise lead to a series of
failing load-balancing attempts leading to a force-migration.
Change-Id: I428875bb6267c780026ef75e2882300738d016e7
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: freedom.tan@mediatek.com
Cc: keita.kobayashi.ym@renesas.com
Cc: mgalbraith@suse.de
Cc: sgurrappadi@nvidia.com
Cc: vincent.guittot@linaro.org
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1476452472-24740-5-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit 9e0994c0a1c1f82c705f1f66388e1bcffcee8bb9)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched/fair.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index d18e2c7b67e5..c00a8ae48a46 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -7569,14 +7569,20 @@ static bool update_sd_pick_busiest(struct lb_env *env, if (sgs->avg_load <= busiest->avg_load) return false; + if (!(env->sd->flags & SD_ASYM_CPUCAPACITY)) + goto asym_packing; + /* - * Candiate sg has no more than one task per cpu and has higher - * per-cpu capacity. No reason to pull tasks to less capable cpus. + * Candidate sg has no more than one task per CPU and + * has higher per-CPU capacity. Migrating tasks to less + * capable CPUs may harm throughput. Maximize throughput, + * power/energy consequences are not considered. */ if (sgs->sum_nr_running <= sgs->group_weight && group_smaller_cpu_capacity(sds->local, sg)) return false; +asym_packing: /* This is the busiest node in its class. */ if (!(env->sd->flags & SD_ASYM_PACKING)) return true; |