forked from luck/tmp_suning_uos_patched
sched: new task placement for vruntime
add proper new task placement for the vruntime based math too. ( note: introduces a swap() macro, but the swap token is too widely used in the kernel namespace for a generic version to be added without changing non-scheduler code - so this cleanup will be done separately. ) Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Mike Galbraith <efault@gmx.de> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
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@ -203,6 +203,20 @@ static struct sched_entity *__pick_next_entity(struct cfs_rq *cfs_rq)
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* Scheduling class statistics methods:
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*/
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static u64 __sched_period(unsigned long nr_running)
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{
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u64 period = sysctl_sched_latency;
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unsigned long nr_latency =
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sysctl_sched_latency / sysctl_sched_min_granularity;
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if (unlikely(nr_running > nr_latency)) {
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period *= nr_running;
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do_div(period, nr_latency);
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}
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return period;
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}
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/*
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* Calculate the preemption granularity needed to schedule every
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* runnable task once per sysctl_sched_latency amount of time.
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@ -1103,6 +1117,8 @@ static void task_tick_fair(struct rq *rq, struct task_struct *curr)
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}
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}
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#define swap(a,b) do { typeof(a) tmp = (a); (a) = (b); (b) = tmp; } while (0)
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/*
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* Share the fairness runtime between parent and child, thus the
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* total amount of pressure for CPU stays equal - new tasks
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@ -1118,14 +1134,9 @@ static void task_new_fair(struct rq *rq, struct task_struct *p)
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sched_info_queued(p);
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update_curr(cfs_rq);
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se->vruntime = cfs_rq->min_vruntime;
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update_stats_enqueue(cfs_rq, se);
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/*
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* Child runs first: we let it run before the parent
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* until it reschedules once. We set up the key so that
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* it will preempt the parent:
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*/
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se->fair_key = curr->fair_key -
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niced_granularity(curr, sched_granularity(cfs_rq)) - 1;
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/*
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* The first wait is dominated by the child-runs-first logic,
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* so do not credit it with that waiting time yet:
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@ -1138,9 +1149,16 @@ static void task_new_fair(struct rq *rq, struct task_struct *p)
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* -granularity/2, so initialize the task with that:
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*/
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if (sched_feat(START_DEBIT))
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se->wait_runtime = -(sched_granularity(cfs_rq) / 2);
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se->wait_runtime = -(__sched_period(cfs_rq->nr_running+1) / 2);
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if (sysctl_sched_child_runs_first &&
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curr->vruntime < se->vruntime) {
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dequeue_entity(cfs_rq, curr, 0);
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swap(curr->vruntime, se->vruntime);
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enqueue_entity(cfs_rq, curr, 0);
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}
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se->vruntime = cfs_rq->min_vruntime;
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update_stats_enqueue(cfs_rq, se);
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__enqueue_entity(cfs_rq, se);
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resched_task(rq->curr);
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