On Fri, 2014-05-09 at 14:36 +0100, Chris Redpath wrote:
When looking for a task to be idle-pulled, don't consider tasks where the affinity does not allow that task to be placed on the target CPU. Also ensure that tasks with restricted affinity do not block selecting other unrestricted busy tasks.
Use the knowledge of target CPU more effectively in idle pull by passing to hmp_get_heaviest_task when we know it, otherwise only checking for general affinity matches with any of the CPUs in the bigger HMP domain.
We still need to explicitly check affinity is allowed in idle pull since if we find no match in hmp_get_heaviest_task we will return the current one, which may not be affine to the new CPU despite having high enough load. In this case, there is nothing to move.
Signed-off-by: Chris Redpath chris.redpath@arm.com Signed-off-by: Jon Medhurst tixy@linaro.org
kernel/sched/fair.c | 42 +++++++++++++++++++++++++++--------------- 1 file changed, 27 insertions(+), 15 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 37f4562..d8fdb8d 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -3721,30 +3721,36 @@ static inline struct hmp_domain *hmp_faster_domain(int cpu); /* must hold runqueue lock for queue se is currently on */ static struct sched_entity *hmp_get_heaviest_task(
struct sched_entity *se, int migrate_up)
struct sched_entity *se, int target_cpu){ int num_tasks = hmp_max_tasks; struct sched_entity *max_se = se; unsigned long int max_ratio = se->avg.load_avg_ratio; const struct cpumask *hmp_target_mask = NULL;
- struct hmp_domain *hmp;
- if (migrate_up) {
struct hmp_domain *hmp;if (hmp_cpu_is_fastest(cpu_of(se->cfs_rq->rq)))return max_se;
- if (hmp_cpu_is_fastest(cpu_of(se->cfs_rq->rq)))
return max_se;
hmp = hmp_faster_domain(cpu_of(se->cfs_rq->rq));hmp_target_mask = &hmp->cpus;
- hmp = hmp_faster_domain(cpu_of(se->cfs_rq->rq));
- hmp_target_mask = &hmp->cpus;
- if (target_cpu >= 0) {
/* idle_balance gets run on a CPU while* it is in the middle of being hotplugged* out. Bail early in that case.*/if(!cpumask_test_cpu(target_cpu, hmp_target_mask))return NULL;hmp_target_mask = cpumask_of(target_cpu);while (num_tasks && se) { if (entity_is_task(se) &&
(se->avg.load_avg_ratio > max_ratio &&hmp_target_mask &&cpumask_intersects(hmp_target_mask,tsk_cpus_allowed(task_of(se))))) {
se->avg.load_avg_ratio > max_ratio &&cpumask_intersects(hmp_target_mask,tsk_cpus_allowed(task_of(se)))) { max_se = se; max_ratio = se->avg.load_avg_ratio;@@ -7153,7 +7159,11 @@ static void hmp_force_up_migration(int this_cpu) } } orig = curr;
curr = hmp_get_heaviest_task(curr, 1);
curr = hmp_get_heaviest_task(curr, -1);if (!curr) {
This case can't happen because hmp_get_heaviest_task can only return zero when we specify a target cpu. However, I like defensive programming and in not making too many assumptions in code, so not going to disagree with adding this check :-)
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