diff options
| -rw-r--r-- | kernel/sched_fair.c | 36 |
1 files changed, 27 insertions, 9 deletions
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index 7041dc697855..95487e3c8b06 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -203,6 +203,20 @@ static struct sched_entity *__pick_next_entity(struct cfs_rq *cfs_rq) * Scheduling class statistics methods: */ +static u64 __sched_period(unsigned long nr_running) +{ + u64 period = sysctl_sched_latency; + unsigned long nr_latency = + sysctl_sched_latency / sysctl_sched_min_granularity; + + if (unlikely(nr_running > nr_latency)) { + period *= nr_running; + do_div(period, nr_latency); + } + + return period; +} + /* * Calculate the preemption granularity needed to schedule every * runnable task once per sysctl_sched_latency amount of time. @@ -1103,6 +1117,8 @@ static void task_tick_fair(struct rq *rq, struct task_struct *curr) } } +#define swap(a,b) do { typeof(a) tmp = (a); (a) = (b); (b) = tmp; } while (0) + /* * Share the fairness runtime between parent and child, thus the * total amount of pressure for CPU stays equal - new tasks @@ -1118,14 +1134,9 @@ static void task_new_fair(struct rq *rq, struct task_struct *p) sched_info_queued(p); update_curr(cfs_rq); + se->vruntime = cfs_rq->min_vruntime; update_stats_enqueue(cfs_rq, se); - /* - * Child runs first: we let it run before the parent - * until it reschedules once. We set up the key so that - * it will preempt the parent: - */ - se->fair_key = curr->fair_key - - niced_granularity(curr, sched_granularity(cfs_rq)) - 1; + /* * The first wait is dominated by the child-runs-first logic, * so do not credit it with that waiting time yet: @@ -1138,9 +1149,16 @@ static void task_new_fair(struct rq *rq, struct task_struct *p) * -granularity/2, so initialize the task with that: */ if (sched_feat(START_DEBIT)) - se->wait_runtime = -(sched_granularity(cfs_rq) / 2); + se->wait_runtime = -(__sched_period(cfs_rq->nr_running+1) / 2); + + if (sysctl_sched_child_runs_first && + curr->vruntime < se->vruntime) { + + dequeue_entity(cfs_rq, curr, 0); + swap(curr->vruntime, se->vruntime); + enqueue_entity(cfs_rq, curr, 0); + } - se->vruntime = cfs_rq->min_vruntime; update_stats_enqueue(cfs_rq, se); __enqueue_entity(cfs_rq, se); resched_task(rq->curr); |