Messages in this thread Patch in this message | | | From | Morten Rasmussen <> | Subject | [PATCH] sched: Update task group load contributions during active load-balancing | Date | Tue, 16 Sep 2014 01:07:10 +0100 |
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Task group load-contributions are not updated when tasks belonging to task groups are migrated by active load-balancing. If no other task belonging to the same task group is already queued at the destination cpu the group sched_entity will be enqueued with load_avg_contrib=0. Hence, weighted_cpuload() won't reflect the newly added load.
The load may remain invisible until the next tick, when the sched_entity load_avg_contrib and task group contributions are reevaluated.
The enqueue loop
for_each_entity(se) { enqueue_entity(cfs_rq,se) ... enqueue_entity_load_avg(cfs_rq,se) ... update_entity_load_avg(se) ... __update_entity_load_avg_contrib(se) ... ... update_cfs_rq_blocked_load(cfs_rq) ... __update_cfs_rq_tg_load_contrib(cfs_rq) ... }
currently skips __update_entity_load_avg_contrib() and __update_cfs_rq_tg_load_contrib() for group entities for active load-balance migrations. The former updates the sched_entity load_avg_contrib, and the latter updates the task group contribution which is needed by the former. They must both be called to ensure that load doesn't temporarily disappear.
cc: Paul Turner <pjt@google.com> cc: Ben Segall <bsegall@google.com>
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com> --- kernel/sched/fair.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index be9e97b..2b6e2eb 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -2521,7 +2521,8 @@ static inline void update_entity_load_avg(struct sched_entity *se, else now = cfs_rq_clock_task(group_cfs_rq(se)); - if (!__update_entity_runnable_avg(now, &se->avg, se->on_rq)) + if (!__update_entity_runnable_avg(now, &se->avg, se->on_rq) && + entity_is_task(se)) return; contrib_delta = __update_entity_load_avg_contrib(se); @@ -2609,6 +2610,10 @@ static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq, cfs_rq->runnable_load_avg += se->avg.load_avg_contrib; /* we force update consideration on load-balancer moves */ update_cfs_rq_blocked_load(cfs_rq, !wakeup); + + /* We force update group contributions on load-balancer moves */ + if (wakeup && !entity_is_task(se)) + __update_cfs_rq_tg_load_contrib(cfs_rq, 0); } /* -- 1.7.9.5
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