diff options
| author | Brendan Jackman <brendan.jackman@arm.com> | 2017-08-31 12:58:01 +0100 |
|---|---|---|
| committer | Chris Redpath <chris.redpath@arm.com> | 2017-10-27 13:30:33 +0100 |
| commit | 411654764590c071ef55242ffd50c4e74930353b (patch) | |
| tree | 8403034a164843822f85c9b3602367cf788054c4 /kernel | |
| parent | 9c825cf6165c1662ce588a1fe11a912eaeaec928 (diff) | |
UPSTREAM: sched/fair: Fix usage of find_idlest_group() when no groups are allowed
When 'p' is not allowed on any of the CPUs in the sched_domain, we
currently return NULL from find_idlest_group(), and pointlessly
continue the search on lower sched_domain levels (where 'p' is also not
allowed) before returning prev_cpu regardless (as we have not updated
new_cpu).
Add an explicit check for this case, and add a comment to
find_idlest_group(). Now when find_idlest_group() returns NULL, it always
means that the local group is allowed and idlest.
Change-Id: I5f2648d2f7fb0465677961ecb7473df3d06f0057
Signed-off-by: Brendan Jackman <brendan.jackman@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20171005114516.18617-5-brendan.jackman@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry-picked-from: commit 6fee85ccbc76 tip:sched/core)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched/fair.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index dc685b67d08b..0e3a9935515c 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5976,6 +5976,8 @@ static unsigned long capacity_spare_wake(int cpu, struct task_struct *p) /* * find_idlest_group finds and returns the least busy CPU group within the * domain. + * + * Assumes p is allowed on at least one CPU in sd. */ static struct sched_group * find_idlest_group(struct sched_domain *sd, struct task_struct *p, @@ -6136,6 +6138,9 @@ static inline int find_idlest_cpu(struct sched_domain *sd, struct task_struct *p schedstat_inc(this_rq(), eas_stats.cas_attempts); } + if (!cpumask_intersects(sched_domain_span(sd), &p->cpus_allowed)) + return prev_cpu; + while (sd) { struct sched_group *group; struct sched_domain *tmp; |