From: Byungchul Park <[email protected]> we have to sync a se with its cfs_rq, when switching sched class to fair class.
current code does not sync it because the se average load won't be valid any more if it has been detached for a long time. however the se's average load would be valid just after being detached from cfs_rq, so we need to sync it in that case, e.g. priority inheritance. to solve the problem that a se average load becomes more useless over time, this patch decays its average load even for the duration that the se has been detached, when it gets attached to the cfs_rq. Signed-off-by: Byungchul Park <[email protected]> --- kernel/sched/fair.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 1be042a..3419f6c 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -2711,6 +2711,17 @@ static inline void update_load_avg(struct sched_entity *se, int update_tg) static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) { + /* + * in case of migration and cgroup-change, more care should be taken + * because se's cfs_rq was changed, that means calling __update_load_avg + * with new cfs_rq->avg.last_update_time is meaningless. so we skip the + * update here. we have to update it with prev cfs_rq just before changing + * se's cfs_rq, and get here soon. + */ + if (se->avg.last_update_time) + __update_load_avg(cfs_rq->avg.last_update_time, cpu_of(rq_of(cfs_rq)), + &se->avg, 0, 0, NULL); + se->avg.last_update_time = cfs_rq->avg.last_update_time; cfs_rq->avg.load_avg += se->avg.load_avg; cfs_rq->avg.load_sum += se->avg.load_sum; @@ -7948,6 +7959,11 @@ static void switched_to_fair(struct rq *rq, struct task_struct *p) se->depth = se->parent ? se->parent->depth + 1 : 0; #endif +#ifdef CONFIG_SMP + /* synchronize task with its cfs_rq */ + attach_entity_load_avg(cfs_rq_of(&p->se), &p->se); +#endif + if (!task_on_rq_queued(p)) { /* @@ -8049,6 +8065,10 @@ static void task_move_group_fair(struct task_struct *p, int queued) detach_entity_load_avg(cfs_rq, se); #endif set_task_rq(p, task_cpu(p)); + + /* tell se's cfs_rq has been changed */ + p->se.avg.last_update_time = 0; + se->depth = se->parent ? se->parent->depth + 1 : 0; cfs_rq = cfs_rq_of(se); if (!queued) -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
