* Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
*/
-/*
- * Tunables that become constants when CONFIG_SCHED_DEBUG is off:
- */
-#ifdef CONFIG_SCHED_DEBUG
-# define const_debug __read_mostly
-#else
-# define const_debug static const
-#endif
-
/*
* Targeted preemption latency for CPU-bound tasks:
* (default: 20ms, units: nanoseconds)
* and reduces their over-scheduling. Synchronous workloads will still
* have immediate wakeup/sleep latencies.
*/
-const_debug unsigned int sysctl_sched_wakeup_granularity = 1000000UL;
+const_debug unsigned int sysctl_sched_wakeup_granularity = 2000000UL;
unsigned int sysctl_sched_runtime_limit __read_mostly;
-/*
- * Debugging: various feature bits
- */
-enum {
- SCHED_FEAT_FAIR_SLEEPERS = 1,
- SCHED_FEAT_SLEEPER_AVG = 2,
- SCHED_FEAT_SLEEPER_LOAD_AVG = 4,
- SCHED_FEAT_START_DEBIT = 8,
- SCHED_FEAT_SKIP_INITIAL = 16,
-};
-
-const_debug unsigned int sysctl_sched_features =
- SCHED_FEAT_FAIR_SLEEPERS *1 |
- SCHED_FEAT_SLEEPER_AVG *0 |
- SCHED_FEAT_SLEEPER_LOAD_AVG *1 |
- SCHED_FEAT_START_DEBIT *1 |
- SCHED_FEAT_SKIP_INITIAL *0;
-
extern struct sched_class fair_sched_class;
/**************************************************************
* CFS operations on generic schedulable entities:
*/
-/* currently running entity (if any) on this cfs_rq */
-static inline struct sched_entity *cfs_rq_curr(struct cfs_rq *cfs_rq)
-{
- return cfs_rq->curr;
-}
-
-static inline void
-set_cfs_rq_curr(struct cfs_rq *cfs_rq, struct sched_entity *se)
-{
- cfs_rq->curr = se;
-}
-
#ifdef CONFIG_FAIR_GROUP_SCHED
/* cpu runqueue to which this cfs_rq is attached */
* Scheduling class tree data structure manipulation methods:
*/
+static inline u64
+max_vruntime(u64 min_vruntime, u64 vruntime)
+{
+ if ((vruntime > min_vruntime) ||
+ (min_vruntime > (1ULL << 61) && vruntime < (1ULL << 50)))
+ min_vruntime = vruntime;
+
+ return min_vruntime;
+}
+
+static inline void
+set_leftmost(struct cfs_rq *cfs_rq, struct rb_node *leftmost)
+{
+ struct sched_entity *se;
+
+ cfs_rq->rb_leftmost = leftmost;
+ if (leftmost)
+ se = rb_entry(leftmost, struct sched_entity, run_node);
+}
+
+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 inline void
+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;
struct sched_entity *entry;
- s64 key = se->fair_key;
+ s64 key = entity_key(cfs_rq, se);
int leftmost = 1;
/*
* We dont care about collisions. Nodes with
* the same key stay together.
*/
- if (key - entry->fair_key < 0) {
+ if (key < entity_key(cfs_rq, entry)) {
link = &parent->rb_left;
} else {
link = &parent->rb_right;
* used):
*/
if (leftmost)
- cfs_rq->rb_leftmost = &se->run_node;
+ set_leftmost(cfs_rq, &se->run_node);
rb_link_node(&se->run_node, parent, link);
rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline);
- update_load_add(&cfs_rq->load, se->load.weight);
- cfs_rq->nr_running++;
- se->on_rq = 1;
-
- schedstat_add(cfs_rq, wait_runtime, se->wait_runtime);
}
-static inline void
+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);
- rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
- update_load_sub(&cfs_rq->load, se->load.weight);
- cfs_rq->nr_running--;
- se->on_rq = 0;
+ set_leftmost(cfs_rq, rb_next(&se->run_node));
- schedstat_add(cfs_rq, wait_runtime, -se->wait_runtime);
+ rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
}
static inline struct rb_node *first_fair(struct cfs_rq *cfs_rq)
return rb_entry(first_fair(cfs_rq), struct sched_entity, run_node);
}
-/**************************************************************
- * Scheduling class statistics methods:
- */
-
-/*
- * Calculate the preemption granularity needed to schedule every
- * runnable task once per sysctl_sched_latency amount of time.
- * (down to a sensible low limit on granularity)
- *
- * For example, if there are 2 tasks running and latency is 10 msecs,
- * we switch tasks every 5 msecs. If we have 3 tasks running, we have
- * to switch tasks every 3.33 msecs to get a 10 msecs observed latency
- * for each task. We do finer and finer scheduling up to until we
- * reach the minimum granularity value.
- *
- * To achieve this we use the following dynamic-granularity rule:
- *
- * gran = lat/nr - lat/nr/nr
- *
- * This comes out of the following equations:
- *
- * kA1 + gran = kB1
- * kB2 + gran = kA2
- * kA2 = kA1
- * kB2 = kB1 - d + d/nr
- * lat = d * nr
- *
- * Where 'k' is key, 'A' is task A (waiting), 'B' is task B (running),
- * '1' is start of time, '2' is end of time, 'd' is delay between
- * 1 and 2 (during which task B was running), 'nr' is number of tasks
- * running, 'lat' is the the period of each task. ('lat' is the
- * sched_latency that we aim for.)
- */
-static long
-sched_granularity(struct cfs_rq *cfs_rq)
+static inline struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
{
- unsigned int gran = sysctl_sched_latency;
- unsigned int nr = cfs_rq->nr_running;
+ struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
+ struct sched_entity *se = NULL;
+ struct rb_node *parent;
- if (nr > 1) {
- gran = gran/nr - gran/nr/nr;
- gran = max(gran, sysctl_sched_min_granularity);
+ while (*link) {
+ parent = *link;
+ se = rb_entry(parent, struct sched_entity, run_node);
+ link = &parent->rb_right;
}
- return gran;
+ return se;
}
-/*
- * We rescale the rescheduling granularity of tasks according to their
- * nice level, but only linearly, not exponentially:
+/**************************************************************
+ * Scheduling class statistics methods:
*/
-static long
-niced_granularity(struct sched_entity *curr, unsigned long granularity)
+
+static u64 __sched_period(unsigned long nr_running)
{
- u64 tmp;
+ u64 period = sysctl_sched_latency;
+ unsigned long nr_latency =
+ sysctl_sched_latency / sysctl_sched_min_granularity;
- if (likely(curr->load.weight == NICE_0_LOAD))
- return granularity;
- /*
- * Positive nice levels get the same granularity as nice-0:
- */
- if (likely(curr->load.weight < NICE_0_LOAD)) {
- tmp = curr->load.weight * (u64)granularity;
- return (long) (tmp >> NICE_0_SHIFT);
+ if (unlikely(nr_running > nr_latency)) {
+ period *= nr_running;
+ do_div(period, nr_latency);
}
- /*
- * Negative nice level tasks get linearly finer
- * granularity:
- */
- tmp = curr->load.inv_weight * (u64)granularity;
- /*
- * It will always fit into 'long':
- */
- return (long) (tmp >> (WMULT_SHIFT-NICE_0_SHIFT));
+ return period;
}
-static inline void
-limit_wait_runtime(struct cfs_rq *cfs_rq, struct sched_entity *se)
+static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
- long limit = sysctl_sched_runtime_limit;
+ u64 period = __sched_period(cfs_rq->nr_running);
- /*
- * Niced tasks have the same history dynamic range as
- * non-niced tasks:
- */
- if (unlikely(se->wait_runtime > limit)) {
- se->wait_runtime = limit;
- schedstat_inc(se, wait_runtime_overruns);
- schedstat_inc(cfs_rq, wait_runtime_overruns);
- }
- if (unlikely(se->wait_runtime < -limit)) {
- se->wait_runtime = -limit;
- schedstat_inc(se, wait_runtime_underruns);
- schedstat_inc(cfs_rq, wait_runtime_underruns);
- }
-}
+ period *= se->load.weight;
+ do_div(period, cfs_rq->load.weight);
-static inline void
-__add_wait_runtime(struct cfs_rq *cfs_rq, struct sched_entity *se, long delta)
-{
- se->wait_runtime += delta;
- schedstat_add(se, sum_wait_runtime, delta);
- limit_wait_runtime(cfs_rq, se);
-}
-
-static void
-add_wait_runtime(struct cfs_rq *cfs_rq, struct sched_entity *se, long delta)
-{
- schedstat_add(cfs_rq, wait_runtime, -se->wait_runtime);
- __add_wait_runtime(cfs_rq, se, delta);
- schedstat_add(cfs_rq, wait_runtime, se->wait_runtime);
+ return period;
}
/*
__update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr,
unsigned long delta_exec)
{
- unsigned long delta, delta_fair, delta_mine;
- struct load_weight *lw = &cfs_rq->load;
- unsigned long load = lw->weight;
+ unsigned long delta_exec_weighted;
+ u64 next_vruntime, min_vruntime;
schedstat_set(curr->exec_max, max((u64)delta_exec, curr->exec_max));
curr->sum_exec_runtime += delta_exec;
- cfs_rq->exec_clock += delta_exec;
-
- if (unlikely(!load))
- return;
-
- delta_fair = calc_delta_fair(delta_exec, lw);
- delta_mine = calc_delta_mine(delta_exec, curr->load.weight, lw);
-
- if (cfs_rq->sleeper_bonus > sysctl_sched_min_granularity) {
- delta = min((u64)delta_mine, cfs_rq->sleeper_bonus);
- delta = min(delta, (unsigned long)(
- (long)sysctl_sched_runtime_limit - curr->wait_runtime));
- cfs_rq->sleeper_bonus -= delta;
- delta_mine -= delta;
+ schedstat_add(cfs_rq, exec_clock, delta_exec);
+ delta_exec_weighted = delta_exec;
+ if (unlikely(curr->load.weight != NICE_0_LOAD)) {
+ delta_exec_weighted = calc_delta_fair(delta_exec_weighted,
+ &curr->load);
}
+ curr->vruntime += delta_exec_weighted;
- cfs_rq->fair_clock += delta_fair;
/*
- * We executed delta_exec amount of time on the CPU,
- * but we were only entitled to delta_mine amount of
- * time during that period (if nr_running == 1 then
- * the two values are equal)
- * [Note: delta_mine - delta_exec is negative]:
+ * maintain cfs_rq->min_vruntime to be a monotonic increasing
+ * value tracking the leftmost vruntime in the tree.
*/
- add_wait_runtime(cfs_rq, curr, delta_mine - delta_exec);
+ if (first_fair(cfs_rq)) {
+ next_vruntime = __pick_next_entity(cfs_rq)->vruntime;
+
+ /* min_vruntime() := !max_vruntime() */
+ min_vruntime = max_vruntime(curr->vruntime, next_vruntime);
+ if (min_vruntime == next_vruntime)
+ min_vruntime = curr->vruntime;
+ else
+ min_vruntime = next_vruntime;
+ } else
+ min_vruntime = curr->vruntime;
+
+ cfs_rq->min_vruntime =
+ max_vruntime(cfs_rq->min_vruntime, min_vruntime);
}
static void update_curr(struct cfs_rq *cfs_rq)
{
- struct sched_entity *curr = cfs_rq_curr(cfs_rq);
+ struct sched_entity *curr = cfs_rq->curr;
u64 now = rq_of(cfs_rq)->clock;
unsigned long delta_exec;
static inline void
update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
- se->wait_start_fair = cfs_rq->fair_clock;
schedstat_set(se->wait_start, rq_of(cfs_rq)->clock);
}
-/*
- * We calculate fair deltas here, so protect against the random effects
- * of a multiplication overflow by capping it to the runtime limit:
- */
-#if BITS_PER_LONG == 32
static inline unsigned long
-calc_weighted(unsigned long delta, unsigned long weight, int shift)
+calc_weighted(unsigned long delta, struct sched_entity *se)
{
- u64 tmp = (u64)delta * weight >> shift;
+ unsigned long weight = se->load.weight;
- if (unlikely(tmp > sysctl_sched_runtime_limit*2))
- return sysctl_sched_runtime_limit*2;
- return tmp;
-}
-#else
-static inline unsigned long
-calc_weighted(unsigned long delta, unsigned long weight, int shift)
-{
- return delta * weight >> shift;
+ if (unlikely(weight != NICE_0_LOAD))
+ return (u64)delta * se->load.weight >> NICE_0_SHIFT;
+ else
+ return delta;
}
-#endif
/*
* Task is being enqueued - update stats:
*/
static void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
- s64 key;
-
/*
* Are we enqueueing a waiting task? (for current tasks
* a dequeue/enqueue event is a NOP)
*/
- if (se != cfs_rq_curr(cfs_rq))
+ if (se != cfs_rq->curr)
update_stats_wait_start(cfs_rq, se);
- /*
- * Update the key:
- */
- key = cfs_rq->fair_clock;
-
- /*
- * Optimize the common nice 0 case:
- */
- if (likely(se->load.weight == NICE_0_LOAD)) {
- key -= se->wait_runtime;
- } else {
- u64 tmp;
-
- if (se->wait_runtime < 0) {
- tmp = -se->wait_runtime;
- key += (tmp * se->load.inv_weight) >>
- (WMULT_SHIFT - NICE_0_SHIFT);
- } else {
- tmp = se->wait_runtime;
- key -= (tmp * se->load.inv_weight) >>
- (WMULT_SHIFT - NICE_0_SHIFT);
- }
- }
-
- se->fair_key = key;
-}
-
-/*
- * Note: must be called with a freshly updated rq->fair_clock.
- */
-static inline void
-__update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se,
- unsigned long delta_fair)
-{
- schedstat_set(se->wait_max, max(se->wait_max,
- rq_of(cfs_rq)->clock - se->wait_start));
-
- if (unlikely(se->load.weight != NICE_0_LOAD))
- delta_fair = calc_weighted(delta_fair, se->load.weight,
- NICE_0_SHIFT);
-
- add_wait_runtime(cfs_rq, se, delta_fair);
}
static void
update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
- unsigned long delta_fair;
-
- if (unlikely(!se->wait_start_fair))
- return;
-
- delta_fair = (unsigned long)min((u64)(2*sysctl_sched_runtime_limit),
- (u64)(cfs_rq->fair_clock - se->wait_start_fair));
-
- __update_stats_wait_end(cfs_rq, se, delta_fair);
-
- se->wait_start_fair = 0;
+ schedstat_set(se->wait_max, max(se->wait_max,
+ rq_of(cfs_rq)->clock - se->wait_start));
schedstat_set(se->wait_start, 0);
}
* Mark the end of the wait period if dequeueing a
* waiting task:
*/
- if (se != cfs_rq_curr(cfs_rq))
+ if (se != cfs_rq->curr)
update_stats_wait_end(cfs_rq, se);
}
* Scheduling class queueing methods:
*/
-static void __enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se,
- unsigned long delta_fair)
+static void
+account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
- unsigned long load = cfs_rq->load.weight;
- long prev_runtime;
-
- /*
- * Do not boost sleepers if there's too much bonus 'in flight'
- * already:
- */
- if (unlikely(cfs_rq->sleeper_bonus > sysctl_sched_runtime_limit))
- return;
-
- if (sysctl_sched_features & SCHED_FEAT_SLEEPER_LOAD_AVG)
- load = rq_of(cfs_rq)->cpu_load[2];
-
- /*
- * Fix up delta_fair with the effect of us running
- * during the whole sleep period:
- */
- if (sysctl_sched_features & SCHED_FEAT_SLEEPER_AVG)
- delta_fair = div64_likely32((u64)delta_fair * load,
- load + se->load.weight);
-
- if (unlikely(se->load.weight != NICE_0_LOAD))
- delta_fair = calc_weighted(delta_fair, se->load.weight,
- NICE_0_SHIFT);
-
- prev_runtime = se->wait_runtime;
- __add_wait_runtime(cfs_rq, se, delta_fair);
- delta_fair = se->wait_runtime - prev_runtime;
+ update_load_add(&cfs_rq->load, se->load.weight);
+ cfs_rq->nr_running++;
+ se->on_rq = 1;
+}
- /*
- * Track the amount of bonus we've given to sleepers:
- */
- cfs_rq->sleeper_bonus += delta_fair;
+static void
+account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+ update_load_sub(&cfs_rq->load, se->load.weight);
+ cfs_rq->nr_running--;
+ se->on_rq = 0;
}
static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
- struct task_struct *tsk = task_of(se);
- unsigned long delta_fair;
-
- if ((entity_is_task(se) && tsk->policy == SCHED_BATCH) ||
- !(sysctl_sched_features & SCHED_FEAT_FAIR_SLEEPERS))
- return;
-
- delta_fair = (unsigned long)min((u64)(2*sysctl_sched_runtime_limit),
- (u64)(cfs_rq->fair_clock - se->sleep_start_fair));
-
- __enqueue_sleeper(cfs_rq, se, delta_fair);
-
- se->sleep_start_fair = 0;
-
#ifdef CONFIG_SCHEDSTATS
if (se->sleep_start) {
u64 delta = rq_of(cfs_rq)->clock - se->sleep_start;
* time that the task spent sleeping:
*/
if (unlikely(prof_on == SLEEP_PROFILING)) {
+ struct task_struct *tsk = task_of(se);
+
profile_hits(SLEEP_PROFILING, (void *)get_wchan(tsk),
delta >> 20);
}
#endif
}
+static void
+place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
+{
+ u64 min_runtime, latency;
+
+ min_runtime = cfs_rq->min_vruntime;
+
+ if (sched_feat(USE_TREE_AVG)) {
+ struct sched_entity *last = __pick_last_entity(cfs_rq);
+ if (last) {
+ min_runtime = __pick_next_entity(cfs_rq)->vruntime;
+ min_runtime += last->vruntime;
+ min_runtime >>= 1;
+ }
+ } else if (sched_feat(APPROX_AVG))
+ min_runtime += sysctl_sched_latency/2;
+
+ if (initial && sched_feat(START_DEBIT))
+ min_runtime += sched_slice(cfs_rq, se);
+
+ if (!initial && sched_feat(NEW_FAIR_SLEEPERS)) {
+ latency = sysctl_sched_latency;
+ if (min_runtime > latency)
+ min_runtime -= latency;
+ else
+ min_runtime = 0;
+ }
+
+ se->vruntime = max(se->vruntime, min_runtime);
+}
+
static void
enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup)
{
*/
update_curr(cfs_rq);
- if (wakeup)
+ if (wakeup) {
+ place_entity(cfs_rq, se, 0);
enqueue_sleeper(cfs_rq, se);
+ }
update_stats_enqueue(cfs_rq, se);
- __enqueue_entity(cfs_rq, se);
+ if (se != cfs_rq->curr)
+ __enqueue_entity(cfs_rq, se);
+ account_entity_enqueue(cfs_rq, se);
}
static void
dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
{
update_stats_dequeue(cfs_rq, se);
- if (sleep) {
- se->sleep_start_fair = cfs_rq->fair_clock;
#ifdef CONFIG_SCHEDSTATS
+ if (sleep) {
if (entity_is_task(se)) {
struct task_struct *tsk = task_of(se);
if (tsk->state & TASK_UNINTERRUPTIBLE)
se->block_start = rq_of(cfs_rq)->clock;
}
-#endif
}
- __dequeue_entity(cfs_rq, se);
+#endif
+ if (se != cfs_rq->curr)
+ __dequeue_entity(cfs_rq, se);
+ account_entity_dequeue(cfs_rq, se);
}
/*
* Preempt the current task with a newly woken task if needed:
*/
static void
-__check_preempt_curr_fair(struct cfs_rq *cfs_rq, struct sched_entity *se,
- struct sched_entity *curr, unsigned long granularity)
+check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
{
- s64 __delta = curr->fair_key - se->fair_key;
unsigned long ideal_runtime, delta_exec;
- /*
- * ideal_runtime is compared against sum_exec_runtime, which is
- * walltime, hence do not scale.
- */
- ideal_runtime = max(sysctl_sched_latency / cfs_rq->nr_running,
- (unsigned long)sysctl_sched_min_granularity);
-
- /*
- * If we executed more than what the latency constraint suggests,
- * reduce the rescheduling granularity. This way the total latency
- * of how much a task is not scheduled converges to
- * sysctl_sched_latency:
- */
+ ideal_runtime = sched_slice(cfs_rq, curr);
delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
if (delta_exec > ideal_runtime)
- granularity = 0;
-
- /*
- * Take scheduling granularity into account - do not
- * preempt the current task unless the best task has
- * a larger than sched_granularity fairness advantage:
- *
- * scale granularity as key space is in fair_clock.
- */
- if (__delta > niced_granularity(curr, granularity))
resched_task(rq_of(cfs_rq)->curr);
}
-static inline void
+static void
set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
- /*
- * Any task has to be enqueued before it get to execute on
- * a CPU. So account for the time it spent waiting on the
- * runqueue. (note, here we rely on pick_next_task() having
- * done a put_prev_task_fair() shortly before this, which
- * updated rq->fair_clock - used by update_stats_wait_end())
- */
- update_stats_wait_end(cfs_rq, se);
+ /* 'current' is not kept within the tree. */
+ if (se->on_rq) {
+ /*
+ * Any task has to be enqueued before it get to execute on
+ * a CPU. So account for the time it spent waiting on the
+ * runqueue.
+ */
+ update_stats_wait_end(cfs_rq, se);
+ __dequeue_entity(cfs_rq, se);
+ }
+
update_stats_curr_start(cfs_rq, se);
- set_cfs_rq_curr(cfs_rq, se);
+ cfs_rq->curr = se;
#ifdef CONFIG_SCHEDSTATS
/*
* Track our maximum slice length, if the CPU's load is at
* least twice that of our own weight (i.e. dont track it
* when there are only lesser-weight tasks around):
*/
- if (rq_of(cfs_rq)->ls.load.weight >= 2*se->load.weight) {
+ if (rq_of(cfs_rq)->load.weight >= 2*se->load.weight) {
se->slice_max = max(se->slice_max,
se->sum_exec_runtime - se->prev_sum_exec_runtime);
}
update_stats_curr_end(cfs_rq, prev);
- if (prev->on_rq)
+ if (prev->on_rq) {
update_stats_wait_start(cfs_rq, prev);
- set_cfs_rq_curr(cfs_rq, NULL);
+ /* Put 'current' back into the tree. */
+ __enqueue_entity(cfs_rq, prev);
+ }
+ cfs_rq->curr = NULL;
}
static void entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
{
- struct sched_entity *next;
-
/*
- * Dequeue and enqueue the task to update its
- * position within the tree:
+ * Update run-time statistics of the 'current'.
*/
- dequeue_entity(cfs_rq, curr, 0);
- enqueue_entity(cfs_rq, curr, 0);
-
- /*
- * Reschedule if another task tops the current one.
- */
- next = __pick_next_entity(cfs_rq);
- if (next == curr)
- return;
+ update_curr(cfs_rq);
- __check_preempt_curr_fair(cfs_rq, next, curr,
- sched_granularity(cfs_rq));
+ if (cfs_rq->nr_running > 1)
+ check_preempt_tick(cfs_rq, curr);
}
/**************************************************
*/
static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu)
{
- /* A later patch will take group into account */
- return &cpu_rq(this_cpu)->cfs;
+ return cfs_rq->tg->cfs_rq[this_cpu];
}
/* Iterate thr' all leaf cfs_rq's on a runqueue */
*
* If compat_yield is turned on then we requeue to the end of the tree.
*/
-static void yield_task_fair(struct rq *rq, struct task_struct *p)
+static void yield_task_fair(struct rq *rq)
{
- struct cfs_rq *cfs_rq = task_cfs_rq(p);
+ struct cfs_rq *cfs_rq = task_cfs_rq(rq->curr);
struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
- struct sched_entity *rightmost, *se = &p->se;
+ struct sched_entity *rightmost, *se = &rq->curr->se;
struct rb_node *parent;
/*
* Dequeue and enqueue the task to update its
* position within the tree:
*/
- dequeue_entity(cfs_rq, &p->se, 0);
- enqueue_entity(cfs_rq, &p->se, 0);
+ dequeue_entity(cfs_rq, se, 0);
+ enqueue_entity(cfs_rq, se, 0);
return;
}
/*
* Minimally necessary key value to be last in the tree:
*/
- se->fair_key = rightmost->fair_key + 1;
+ se->vruntime = rightmost->vruntime + 1;
if (cfs_rq->rb_leftmost == &se->run_node)
cfs_rq->rb_leftmost = rb_next(&se->run_node);
/*
* Preempt the current task with a newly woken task if needed:
*/
-static void check_preempt_curr_fair(struct rq *rq, struct task_struct *p)
+static void check_preempt_wakeup(struct rq *rq, struct task_struct *p)
{
struct task_struct *curr = rq->curr;
struct cfs_rq *cfs_rq = task_cfs_rq(curr);
- unsigned long gran;
if (unlikely(rt_prio(p->prio))) {
update_rq_clock(rq);
resched_task(curr);
return;
}
+ if (is_same_group(curr, p)) {
+ s64 delta = curr->se.vruntime - p->se.vruntime;
- gran = sysctl_sched_wakeup_granularity;
- /*
- * Batch tasks prefer throughput over latency:
- */
- if (unlikely(p->policy == SCHED_BATCH))
- gran = sysctl_sched_batch_wakeup_granularity;
-
- if (is_same_group(curr, p))
- __check_preempt_curr_fair(cfs_rq, &p->se, &curr->se, gran);
+ if (delta > (s64)sysctl_sched_wakeup_granularity)
+ resched_task(curr);
+ }
}
static struct task_struct *pick_next_task_fair(struct rq *rq)
}
}
+#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
static void task_new_fair(struct rq *rq, struct task_struct *p)
{
struct cfs_rq *cfs_rq = task_cfs_rq(p);
- struct sched_entity *se = &p->se, *curr = cfs_rq_curr(cfs_rq);
+ struct sched_entity *se = &p->se, *curr = cfs_rq->curr;
sched_info_queued(p);
update_curr(cfs_rq);
- 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:
- */
- if (sysctl_sched_features & SCHED_FEAT_SKIP_INITIAL)
- se->wait_start_fair = 0;
+ place_entity(cfs_rq, se, 1);
- /*
- * The statistical average of wait_runtime is about
- * -granularity/2, so initialize the task with that:
- */
- if (sysctl_sched_features & SCHED_FEAT_START_DEBIT)
- se->wait_runtime = -(sched_granularity(cfs_rq) / 2);
+ if (sysctl_sched_child_runs_first &&
+ curr->vruntime < se->vruntime) {
+ /*
+ * Upon rescheduling, sched_class::put_prev_task() will place
+ * 'current' within the tree based on its new key value.
+ */
+ swap(curr->vruntime, se->vruntime);
+ }
+ update_stats_enqueue(cfs_rq, se);
__enqueue_entity(cfs_rq, se);
+ account_entity_enqueue(cfs_rq, se);
resched_task(rq->curr);
}
-#ifdef CONFIG_FAIR_GROUP_SCHED
/* Account for a task changing its policy or group.
*
* This routine is mostly called to set cfs_rq->curr field when a task
for_each_sched_entity(se)
set_next_entity(cfs_rq_of(se), se);
}
-#else
-static void set_curr_task_fair(struct rq *rq)
-{
-}
-#endif
/*
* All the scheduling class methods:
.dequeue_task = dequeue_task_fair,
.yield_task = yield_task_fair,
- .check_preempt_curr = check_preempt_curr_fair,
+ .check_preempt_curr = check_preempt_wakeup,
.pick_next_task = pick_next_task_fair,
.put_prev_task = put_prev_task_fair,
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