* (default: 20ms, units: nanoseconds)
*
* NOTE: this latency value is not the same as the concept of
- * 'timeslice length' - timeslices in CFS are of variable length.
- * (to see the precise effective timeslice length of your workload,
- * run vmstat and monitor the context-switches field)
+ * 'timeslice length' - timeslices in CFS are of variable length
+ * and have no persistent notion like in traditional, time-slice
+ * based scheduling concepts.
*
- * On SMP systems the value of this is multiplied by the log2 of the
- * number of CPUs. (i.e. factor 2x on 2-way systems, 3x on 4-way
- * systems, 4x on 8-way systems, 5x on 16-way systems, etc.)
- * Targeted preemption latency for CPU-bound tasks:
+ * (to see the precise effective timeslice length of your workload,
+ * run vmstat and monitor the context-switches (cs) field)
*/
const_debug unsigned int sysctl_sched_latency = 20000000ULL;
*/
const_debug unsigned int sysctl_sched_wakeup_granularity = 10000000UL;
+const_debug unsigned int sysctl_sched_migration_cost = 500000UL;
+
/**************************************************************
* CFS operations on generic schedulable entities:
*/
* Scheduling class tree data structure manipulation methods:
*/
-static inline u64
-max_vruntime(u64 min_vruntime, u64 vruntime)
+static inline u64 max_vruntime(u64 min_vruntime, u64 vruntime)
{
s64 delta = (s64)(vruntime - min_vruntime);
if (delta > 0)
return min_vruntime;
}
-static inline u64
-min_vruntime(u64 min_vruntime, u64 vruntime)
+static inline u64 min_vruntime(u64 min_vruntime, u64 vruntime)
{
s64 delta = (s64)(vruntime - min_vruntime);
if (delta < 0)
return min_vruntime;
}
-static inline s64
-entity_key(struct cfs_rq *cfs_rq, struct sched_entity *se)
+static inline s64 entity_key(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
return se->vruntime - cfs_rq->min_vruntime;
}
/*
* Enqueue an entity into the rb-tree:
*/
-static void
-__enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
+static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
struct rb_node *parent = NULL;
rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline);
}
-static void
-__dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
+static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
if (cfs_rq->rb_leftmost == &se->run_node)
cfs_rq->rb_leftmost = rb_next(&se->run_node);
static inline void
update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
- update_curr(cfs_rq);
/*
* Mark the end of the wait period if dequeueing a
* waiting task:
se->exec_start = rq_of(cfs_rq)->clock;
}
-/*
- * We are descheduling a task - update its stats:
- */
-static inline void
-update_stats_curr_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
-{
- se->exec_start = 0;
-}
-
/**************************************************
* Scheduling class queueing methods:
*/
vruntime = cfs_rq->min_vruntime;
- if (sched_feat(USE_TREE_AVG)) {
+ if (sched_feat(TREE_AVG)) {
struct sched_entity *last = __pick_last_entity(cfs_rq);
if (last) {
vruntime += last->vruntime;
vruntime += sched_vslice_add(cfs_rq, se);
if (!initial) {
- if (sched_feat(NEW_FAIR_SLEEPERS))
+ if (sched_feat(NEW_FAIR_SLEEPERS) && entity_is_task(se) &&
+ task_of(se)->policy != SCHED_BATCH)
vruntime -= sysctl_sched_latency;
vruntime = max_t(s64, vruntime, se->vruntime);
enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup)
{
/*
- * Update the fair clock.
+ * Update run-time statistics of the 'current'.
*/
update_curr(cfs_rq);
static void
dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
{
+ /*
+ * Update run-time statistics of the 'current'.
+ */
+ update_curr(cfs_rq);
+
update_stats_dequeue(cfs_rq, se);
if (sleep) {
+ se->peer_preempt = 0;
#ifdef CONFIG_SCHEDSTATS
if (entity_is_task(se)) {
struct task_struct *tsk = task_of(se);
ideal_runtime = sched_slice(cfs_rq, curr);
delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
- if (delta_exec > ideal_runtime)
+ if (delta_exec > ideal_runtime ||
+ (sched_feat(PREEMPT_RESTRICT) && curr->peer_preempt))
resched_task(rq_of(cfs_rq)->curr);
+ curr->peer_preempt = 0;
}
static void
if (prev->on_rq)
update_curr(cfs_rq);
- update_stats_curr_end(cfs_rq, prev);
-
check_spread(cfs_rq, prev);
if (prev->on_rq) {
update_stats_wait_start(cfs_rq, prev);
*/
update_curr(cfs_rq);
- if (cfs_rq->nr_running > 1)
+ if (cfs_rq->nr_running > 1 || !sched_feat(WAKEUP_PREEMPT))
check_preempt_tick(cfs_rq, curr);
}
if (likely(!sysctl_sched_compat_yield)) {
__update_rq_clock(rq);
/*
- * Dequeue and enqueue the task to update its
- * position within the tree:
+ * Update run-time statistics of the 'current'.
*/
update_curr(cfs_rq);
struct task_struct *curr = rq->curr;
struct cfs_rq *cfs_rq = task_cfs_rq(curr);
struct sched_entity *se = &curr->se, *pse = &p->se;
- s64 delta;
+ s64 delta, gran;
if (unlikely(rt_prio(p->prio))) {
update_rq_clock(rq);
resched_task(curr);
return;
}
+ /*
+ * Batch tasks do not preempt (their preemption is driven by
+ * the tick):
+ */
+ if (unlikely(p->policy == SCHED_BATCH))
+ return;
- while (!is_same_group(se, pse)) {
- se = parent_entity(se);
- pse = parent_entity(pse);
- }
+ if (sched_feat(WAKEUP_PREEMPT)) {
+ while (!is_same_group(se, pse)) {
+ se = parent_entity(se);
+ pse = parent_entity(pse);
+ }
- delta = se->vruntime - pse->vruntime;
+ delta = se->vruntime - pse->vruntime;
+ gran = sysctl_sched_wakeup_granularity;
+ if (unlikely(se->load.weight != NICE_0_LOAD))
+ gran = calc_delta_fair(gran, &se->load);
- if (delta > (s64)sysctl_sched_wakeup_granularity)
- resched_task(curr);
+ if (delta > gran) {
+ int now = !sched_feat(PREEMPT_RESTRICT);
+
+ if (now || p->prio < curr->prio || !se->peer_preempt++)
+ resched_task(curr);
+ }
+ }
}
static struct task_struct *pick_next_task_fair(struct rq *rq)
{
struct cfs_rq *cfs_rq = task_cfs_rq(p);
struct sched_entity *se = &p->se, *curr = cfs_rq->curr;
+ int this_cpu = smp_processor_id();
sched_info_queued(p);
update_curr(cfs_rq);
place_entity(cfs_rq, se, 1);
- if (sysctl_sched_child_runs_first &&
+ if (sysctl_sched_child_runs_first && this_cpu == task_cpu(p) &&
curr->vruntime < se->vruntime) {
/*
* Upon rescheduling, sched_class::put_prev_task() will place
check_spread(cfs_rq, curr);
__enqueue_entity(cfs_rq, se);
account_entity_enqueue(cfs_rq, se);
+ se->peer_preempt = 0;
resched_task(rq->curr);
}
projects / cascardo / linux.git / blobdiff