From 4d8d595dfa69e1c807bf928f364668a7f30da5dc Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 27 Jun 2008 13:41:19 +0200 Subject: [PATCH] sched: update aggregate when holding the RQs It was observed that in __update_group_shares_cpu() rq_weight > aggregate()->rq_weight This is caused by forks/wakeups in between the initial aggregate pass and locking of the RQs for load balance. To avoid this situation partially re-do the aggregation once we have the RQs locked (which avoids new tasks from appearing). Signed-off-by: Peter Zijlstra Cc: Srivatsa Vaddagiri Cc: Mike Galbraith Signed-off-by: Ingo Molnar --- kernel/sched.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/kernel/sched.c b/kernel/sched.c index 160d3c209b..dae20199dc 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -1721,6 +1721,11 @@ aggregate_get_up(struct task_group *tg, int cpu, struct sched_domain *sd) aggregate_group_set_shares(tg, cpu, sd); } +static void +aggregate_get_nop(struct task_group *tg, int cpu, struct sched_domain *sd) +{ +} + static DEFINE_PER_CPU(spinlock_t, aggregate_lock); static void __init init_aggregate(void) @@ -1740,6 +1745,11 @@ static int get_aggregate(int cpu, struct sched_domain *sd) return 1; } +static void update_aggregate(int cpu, struct sched_domain *sd) +{ + aggregate_walk_tree(aggregate_get_down, aggregate_get_nop, cpu, sd); +} + static void put_aggregate(int cpu, struct sched_domain *sd) { spin_unlock(&per_cpu(aggregate_lock, cpu)); @@ -1761,6 +1771,10 @@ static inline int get_aggregate(int cpu, struct sched_domain *sd) return 0; } +static inline void update_aggregate(int cpu, struct sched_domain *sd) +{ +} + static inline void put_aggregate(int cpu, struct sched_domain *sd) { } @@ -2192,6 +2206,12 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu) int load_idx = sd->forkexec_idx; int imbalance = 100 + (sd->imbalance_pct-100)/2; + /* + * now that we have both rqs locked the rq weight won't change + * anymore - so update the stats. + */ + update_aggregate(this_cpu, sd); + do { unsigned long load, avg_load; int local_group; -- 2.39.5