From f0862cb749c537c32de82912d30110098ddc6cd6 Mon Sep 17 00:00:00 2001 From: Alex Shi Date: Thu, 20 Jun 2013 10:18:48 +0800 Subject: [PATCH 1/2] sched: Fix sleep time double accounting in enqueue entity The woken migrated task will __synchronize_entity_decay(se); in migrate_task_rq_fair, then it needs to set `se->avg.last_runnable_update -= (-se->avg.decay_count) << 20' before update_entity_load_avg, in order to avoid sleep time is updated twice for se.avg.load_avg_contrib in both __syncchronize and update_entity_load_avg. However if the sleeping task is woken up from the same cpu, it miss the last_runnable_update before update_entity_load_avg(se, 0, 1), then the sleep time was used twice in both functions. So we need to remove the double sleep time accounting. Paul also contributed some code comments in this commit. Signed-off-by: Alex Shi Reviewed-by: Paul Turner Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1371694737-29336-5-git-send-email-alex.shi@intel.com Signed-off-by: Ingo Molnar --- kernel/sched/fair.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 8a4a02740f0a..b1e9def76b55 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1714,7 +1714,13 @@ static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq, } wakeup = 0; } else { - __synchronize_entity_decay(se); + /* + * Task re-woke on same cpu (or else migrate_task_rq_fair() + * would have made count negative); we must be careful to avoid + * double-accounting blocked time after synchronizing decays. + */ + se->avg.last_runnable_update += __synchronize_entity_decay(se) + << 20; } /* migrated tasks did not contribute to our blocked load */ From 916ff46934c350d6dee3c02da62950539559922c Mon Sep 17 00:00:00 2001 From: Kamalesh Babulal Date: Tue, 25 Jun 2013 13:33:36 +0530 Subject: [PATCH 2/2] sched/debug: Add load-tracking statistics to task At present we print per-entity load-tracking statistics for cfs_rq of cgroups/runqueues. Given that per task statistics is maintained, it can be used to know the contribution made by the task to its parenting cfs_rq level. This patch adds per-task load-tracking statistics to /proc//sched. Signed-off-by: Kamalesh Babulal Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20130625080336.GA20175@linux.vnet.ibm.com Signed-off-by: Ingo Molnar --- kernel/sched/debug.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index fbd8caa83ef5..6b7b86cfabad 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -569,6 +569,12 @@ void proc_sched_show_task(struct task_struct *p, struct seq_file *m) "nr_involuntary_switches", (long long)p->nivcsw); P(se.load.weight); +#if defined(CONFIG_SMP) && defined(CONFIG_FAIR_GROUP_SCHED) + P(se.avg.runnable_avg_sum); + P(se.avg.runnable_avg_period); + P(se.avg.load_avg_contrib); + P(se.avg.decay_count); +#endif P(policy); P(prio); #undef PN