From: Paul Turner Date: Thu, 21 Jul 2011 16:43:27 +0000 (-0700) Subject: sched: Implement hierarchical task accounting for SCHED_OTHER X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=953bfcd10e6f3697233e8e5128c611d275da39c1;p=linux-beck.git sched: Implement hierarchical task accounting for SCHED_OTHER Introduce hierarchical task accounting for the group scheduling case in CFS, as well as promoting the responsibility for maintaining rq->nr_running to the scheduling classes. The primary motivation for this is that with scheduling classes supporting bandwidth throttling it is possible for entities participating in throttled sub-trees to not have root visible changes in rq->nr_running across activate and de-activate operations. This in turn leads to incorrect idle and weight-per-task load balance decisions. This also allows us to make a small fixlet to the fastpath in pick_next_task() under group scheduling. Note: this issue also exists with the existing sched_rt throttling mechanism. This patch does not address that. Signed-off-by: Paul Turner Reviewed-by: Hidetoshi Seto Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20110721184756.878333391@google.com Signed-off-by: Ingo Molnar --- diff --git a/kernel/sched.c b/kernel/sched.c index cf427bb2b65e..cd1a531ca8ff 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -311,7 +311,7 @@ struct task_group root_task_group; /* CFS-related fields in a runqueue */ struct cfs_rq { struct load_weight load; - unsigned long nr_running; + unsigned long nr_running, h_nr_running; u64 exec_clock; u64 min_vruntime; @@ -1802,7 +1802,6 @@ static void activate_task(struct rq *rq, struct task_struct *p, int flags) rq->nr_uninterruptible--; enqueue_task(rq, p, flags); - inc_nr_running(rq); } /* @@ -1814,7 +1813,6 @@ static void deactivate_task(struct rq *rq, struct task_struct *p, int flags) rq->nr_uninterruptible++; dequeue_task(rq, p, flags); - dec_nr_running(rq); } #ifdef CONFIG_IRQ_TIME_ACCOUNTING @@ -4258,7 +4256,7 @@ pick_next_task(struct rq *rq) * Optimization: we know that if all tasks are in * the fair class we can call that function directly: */ - if (likely(rq->nr_running == rq->cfs.nr_running)) { + if (likely(rq->nr_running == rq->cfs.h_nr_running)) { p = fair_sched_class.pick_next_task(rq); if (likely(p)) return p; diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index f4b732a3552b..f86b0cb5eb29 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -1310,16 +1310,19 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) break; cfs_rq = cfs_rq_of(se); enqueue_entity(cfs_rq, se, flags); + cfs_rq->h_nr_running++; flags = ENQUEUE_WAKEUP; } for_each_sched_entity(se) { cfs_rq = cfs_rq_of(se); + cfs_rq->h_nr_running++; update_cfs_load(cfs_rq, 0); update_cfs_shares(cfs_rq); } + inc_nr_running(rq); hrtick_update(rq); } @@ -1339,6 +1342,7 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) for_each_sched_entity(se) { cfs_rq = cfs_rq_of(se); dequeue_entity(cfs_rq, se, flags); + cfs_rq->h_nr_running--; /* Don't dequeue parent if it has other entities besides us */ if (cfs_rq->load.weight) { @@ -1358,11 +1362,13 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) for_each_sched_entity(se) { cfs_rq = cfs_rq_of(se); + cfs_rq->h_nr_running--; update_cfs_load(cfs_rq, 0); update_cfs_shares(cfs_rq); } + dec_nr_running(rq); hrtick_update(rq); } diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c index a8c207ff3492..a9d3c6bc684a 100644 --- a/kernel/sched_rt.c +++ b/kernel/sched_rt.c @@ -936,6 +936,8 @@ enqueue_task_rt(struct rq *rq, struct task_struct *p, int flags) if (!task_current(rq, p) && p->rt.nr_cpus_allowed > 1) enqueue_pushable_task(rq, p); + + inc_nr_running(rq); } static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags) @@ -946,6 +948,8 @@ static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags) dequeue_rt_entity(rt_se); dequeue_pushable_task(rq, p); + + dec_nr_running(rq); } /* @@ -1841,4 +1845,3 @@ static void print_rt_stats(struct seq_file *m, int cpu) rcu_read_unlock(); } #endif /* CONFIG_SCHED_DEBUG */ - diff --git a/kernel/sched_stoptask.c b/kernel/sched_stoptask.c index 6f437632afab..8b44e7fa7fb3 100644 --- a/kernel/sched_stoptask.c +++ b/kernel/sched_stoptask.c @@ -34,11 +34,13 @@ static struct task_struct *pick_next_task_stop(struct rq *rq) static void enqueue_task_stop(struct rq *rq, struct task_struct *p, int flags) { + inc_nr_running(rq); } static void dequeue_task_stop(struct rq *rq, struct task_struct *p, int flags) { + dec_nr_running(rq); } static void yield_task_stop(struct rq *rq)