diff options
| author | Vincent Guittot <vincent.guittot@linaro.org> | 2019-10-18 15:26:34 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2019-10-21 09:40:54 +0200 |
| commit | 2ab4092fc82d6001fdd9d51dbba27d04dec967e0 (patch) | |
| tree | cc3411cf40c445f3ea352ae2f86a1c13e1bcbd57 | |
| parent | b0fb1eb4f04ae4768231b9731efb1134e22053a4 (diff) | |
| download | linux-2ab4092fc82d6001fdd9d51dbba27d04dec967e0.tar.bz2 | |
sched/fair: Spread out tasks evenly when not overloaded
When there is only one CPU per group, using the idle CPUs to evenly spread
tasks doesn't make sense and nr_running is a better metrics.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: hdanton@sina.com
Cc: parth@linux.ibm.com
Cc: pauld@redhat.com
Cc: quentin.perret@arm.com
Cc: riel@surriel.com
Cc: srikar@linux.vnet.ibm.com
Cc: valentin.schneider@arm.com
Link: https://lkml.kernel.org/r/1571405198-27570-8-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | kernel/sched/fair.c | 40 |
1 files changed, 28 insertions, 12 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index e6a3db08481c..f489f603f317 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -8591,18 +8591,34 @@ static struct sched_group *find_busiest_group(struct lb_env *env) busiest->sum_nr_running > local->sum_nr_running + 1) goto force_balance; - if (busiest->group_type != group_overloaded && - (env->idle == CPU_NOT_IDLE || - local->idle_cpus <= (busiest->idle_cpus + 1))) - /* - * If the busiest group is not overloaded - * and there is no imbalance between this and busiest group - * wrt. idle CPUs, it is balanced. The imbalance - * becomes significant if the diff is greater than 1 otherwise - * we might end up just moving the imbalance to another - * group. - */ - goto out_balanced; + if (busiest->group_type != group_overloaded) { + if (env->idle == CPU_NOT_IDLE) + /* + * If the busiest group is not overloaded (and as a + * result the local one too) but this CPU is already + * busy, let another idle CPU try to pull task. + */ + goto out_balanced; + + if (busiest->group_weight > 1 && + local->idle_cpus <= (busiest->idle_cpus + 1)) + /* + * If the busiest group is not overloaded + * and there is no imbalance between this and busiest + * group wrt idle CPUs, it is balanced. The imbalance + * becomes significant if the diff is greater than 1 + * otherwise we might end up to just move the imbalance + * on another group. Of course this applies only if + * there is more than 1 CPU per group. + */ + goto out_balanced; + + if (busiest->sum_h_nr_running == 1) + /* + * busiest doesn't have any tasks waiting to run + */ + goto out_balanced; + } force_balance: /* Looks like there is an imbalance. Compute it */ |