*/
#include <linux/latencytop.h>
+#include <linux/sched.h>
/*
* Targeted preemption latency for CPU-bound tasks:
* run vmstat and monitor the context-switches (cs) field)
*/
unsigned int sysctl_sched_latency = 5000000ULL;
+unsigned int normalized_sysctl_sched_latency = 5000000ULL;
+
+/*
+ * The initial- and re-scaling of tunables is configurable
+ * (default SCHED_TUNABLESCALING_LOG = *(1+ilog(ncpus))
+ *
+ * Options are:
+ * SCHED_TUNABLESCALING_NONE - unscaled, always *1
+ * SCHED_TUNABLESCALING_LOG - scaled logarithmical, *1+ilog(ncpus)
+ * SCHED_TUNABLESCALING_LINEAR - scaled linear, *ncpus
+ */
+enum sched_tunable_scaling sysctl_sched_tunable_scaling
+ = SCHED_TUNABLESCALING_LOG;
/*
* Minimal preemption granularity for CPU-bound tasks:
* (default: 1 msec * (1 + ilog(ncpus)), units: nanoseconds)
*/
unsigned int sysctl_sched_min_granularity = 1000000ULL;
+unsigned int normalized_sysctl_sched_min_granularity = 1000000ULL;
/*
* is kept at sysctl_sched_latency / sysctl_sched_min_granularity
* have immediate wakeup/sleep latencies.
*/
unsigned int sysctl_sched_wakeup_granularity = 1000000UL;
+unsigned int normalized_sysctl_sched_wakeup_granularity = 1000000UL;
const_debug unsigned int sysctl_sched_migration_cost = 500000UL;
*/
#ifdef CONFIG_SCHED_DEBUG
-int sched_nr_latency_handler(struct ctl_table *table, int write,
+int sched_proc_update_handler(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp,
loff_t *ppos)
{
int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+ int factor = get_update_sysctl_factor();
if (ret || !write)
return ret;
sched_nr_latency = DIV_ROUND_UP(sysctl_sched_latency,
sysctl_sched_min_granularity);
+#define WRT_SYSCTL(name) \
+ (normalized_sysctl_##name = sysctl_##name / (factor))
+ WRT_SYSCTL(sched_min_granularity);
+ WRT_SYSCTL(sched_latency);
+ WRT_SYSCTL(sched_wakeup_granularity);
+ WRT_SYSCTL(sched_shares_ratelimit);
+#undef WRT_SYSCTL
+
return 0;
}
#endif
curr->sum_exec_runtime += delta_exec;
schedstat_add(cfs_rq, exec_clock, delta_exec);
delta_exec_weighted = calc_delta_fair(delta_exec, curr);
+
curr->vruntime += delta_exec_weighted;
update_min_vruntime(cfs_rq);
}
se->vruntime = vruntime;
}
+#define ENQUEUE_WAKEUP 1
+#define ENQUEUE_MIGRATE 2
+
static void
-enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup)
+enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
{
/*
+ * Update the normalized vruntime before updating min_vruntime
+ * through callig update_curr().
+ */
+ if (!(flags & ENQUEUE_WAKEUP) || (flags & ENQUEUE_MIGRATE))
+ se->vruntime += cfs_rq->min_vruntime;
+
+ /*
* Update run-time statistics of the 'current'.
*/
update_curr(cfs_rq);
account_entity_enqueue(cfs_rq, se);
- if (wakeup) {
+ if (flags & ENQUEUE_WAKEUP) {
place_entity(cfs_rq, se, 0);
enqueue_sleeper(cfs_rq, se);
}
__dequeue_entity(cfs_rq, se);
account_entity_dequeue(cfs_rq, se);
update_min_vruntime(cfs_rq);
+
+ /*
+ * Normalize the entity after updating the min_vruntime because the
+ * update can refer to the ->curr item and we need to reflect this
+ * movement in our normalized position.
+ */
+ if (!sleep)
+ se->vruntime -= cfs_rq->min_vruntime;
}
/*
* re-elected due to buddy favours.
*/
clear_buddies(cfs_rq, curr);
+ return;
+ }
+
+ /*
+ * Ensure that a task that missed wakeup preemption by a
+ * narrow margin doesn't have to wait for a full slice.
+ * This also mitigates buddy induced latencies under load.
+ */
+ if (!sched_feat(WAKEUP_PREEMPT))
+ return;
+
+ if (delta_exec < sysctl_sched_min_granularity)
+ return;
+
+ if (cfs_rq->nr_running > 1) {
+ struct sched_entity *se = __pick_next_entity(cfs_rq);
+ s64 delta = curr->vruntime - se->vruntime;
+
+ if (delta > ideal_runtime)
+ resched_task(rq_of(cfs_rq)->curr);
}
}
static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq)
{
struct sched_entity *se = __pick_next_entity(cfs_rq);
+ struct sched_entity *left = se;
- if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, se) < 1)
- return cfs_rq->next;
+ if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1)
+ se = cfs_rq->next;
- if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, se) < 1)
- return cfs_rq->last;
+ /*
+ * Prefer last buddy, try to return the CPU to a preempted task.
+ */
+ if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1)
+ se = cfs_rq->last;
+
+ clear_buddies(cfs_rq, se);
return se;
}
{
struct cfs_rq *cfs_rq;
struct sched_entity *se = &p->se;
+ int flags = 0;
+
+ if (wakeup)
+ flags |= ENQUEUE_WAKEUP;
+ if (p->state == TASK_WAKING)
+ flags |= ENQUEUE_MIGRATE;
for_each_sched_entity(se) {
if (se->on_rq)
break;
cfs_rq = cfs_rq_of(se);
- enqueue_entity(cfs_rq, se, wakeup);
- wakeup = 1;
+ enqueue_entity(cfs_rq, se, flags);
+ flags = ENQUEUE_WAKEUP;
}
hrtick_update(rq);
#ifdef CONFIG_SMP
+static void task_waking_fair(struct rq *rq, struct task_struct *p)
+{
+ struct sched_entity *se = &p->se;
+ struct cfs_rq *cfs_rq = cfs_rq_of(se);
+
+ se->vruntime -= cfs_rq->min_vruntime;
+}
+
#ifdef CONFIG_FAIR_GROUP_SCHED
/*
* effective_load() calculates the load change as seen from the root_task_group
new_cpu = prev_cpu;
}
- rcu_read_lock();
for_each_domain(cpu, tmp) {
+ if (!(tmp->flags & SD_LOAD_BALANCE))
+ continue;
+
/*
* If power savings logic is enabled for a domain, see if we
* are not overloaded, if so, don't balance wider.
update_shares(tmp);
}
- if (affine_sd && wake_affine(affine_sd, p, sync)) {
- new_cpu = cpu;
- goto out;
- }
+ if (affine_sd && wake_affine(affine_sd, p, sync))
+ return cpu;
while (sd) {
int load_idx = sd->forkexec_idx;
/* while loop will break here if sd == NULL */
}
-out:
- rcu_read_unlock();
return new_cpu;
}
#endif /* CONFIG_SMP */
struct sched_entity *se = &curr->se, *pse = &p->se;
struct cfs_rq *cfs_rq = task_cfs_rq(curr);
int sync = wake_flags & WF_SYNC;
+ int scale = cfs_rq->nr_running >= sched_nr_latency;
- update_curr(cfs_rq);
-
- if (unlikely(rt_prio(p->prio))) {
- resched_task(curr);
- return;
- }
+ if (unlikely(rt_prio(p->prio)))
+ goto preempt;
if (unlikely(p->sched_class != &fair_sched_class))
return;
if (unlikely(se == pse))
return;
- /*
- * Only set the backward buddy when the current task is still on the
- * rq. This can happen when a wakeup gets interleaved with schedule on
- * the ->pre_schedule() or idle_balance() point, either of which can
- * drop the rq lock.
- *
- * Also, during early boot the idle thread is in the fair class, for
- * obvious reasons its a bad idea to schedule back to the idle thread.
- */
- if (sched_feat(LAST_BUDDY) && likely(se->on_rq && curr != rq->idle))
- set_last_buddy(se);
- if (sched_feat(NEXT_BUDDY) && !(wake_flags & WF_FORK))
+ if (sched_feat(NEXT_BUDDY) && scale && !(wake_flags & WF_FORK))
set_next_buddy(pse);
/*
return;
/* Idle tasks are by definition preempted by everybody. */
- if (unlikely(curr->policy == SCHED_IDLE)) {
- resched_task(curr);
- return;
- }
+ if (unlikely(curr->policy == SCHED_IDLE))
+ goto preempt;
- if ((sched_feat(WAKEUP_SYNC) && sync) ||
- (sched_feat(WAKEUP_OVERLAP) &&
- (se->avg_overlap < sysctl_sched_migration_cost &&
- pse->avg_overlap < sysctl_sched_migration_cost))) {
- resched_task(curr);
- return;
- }
+ if (sched_feat(WAKEUP_SYNC) && sync)
+ goto preempt;
- if (sched_feat(WAKEUP_RUNNING)) {
- if (pse->avg_running < se->avg_running) {
- set_next_buddy(pse);
- resched_task(curr);
- return;
- }
- }
+ if (sched_feat(WAKEUP_OVERLAP) &&
+ se->avg_overlap < sysctl_sched_migration_cost &&
+ pse->avg_overlap < sysctl_sched_migration_cost)
+ goto preempt;
if (!sched_feat(WAKEUP_PREEMPT))
return;
+ update_curr(cfs_rq);
find_matching_se(&se, &pse);
-
BUG_ON(!pse);
-
if (wakeup_preempt_entity(se, pse) == 1)
- resched_task(curr);
+ goto preempt;
+
+ return;
+
+preempt:
+ resched_task(curr);
+ /*
+ * Only set the backward buddy when the current task is still
+ * on the rq. This can happen when a wakeup gets interleaved
+ * with schedule on the ->pre_schedule() or idle_balance()
+ * point, either of which can * drop the rq lock.
+ *
+ * Also, during early boot the idle thread is in the fair class,
+ * for obvious reasons its a bad idea to schedule back to it.
+ */
+ if (unlikely(!se->on_rq || curr == rq->idle))
+ return;
+
+ if (sched_feat(LAST_BUDDY) && scale && entity_is_task(se))
+ set_last_buddy(se);
}
static struct task_struct *pick_next_task_fair(struct rq *rq)
do {
se = pick_next_entity(cfs_rq);
- /*
- * If se was a buddy, clear it so that it will have to earn
- * the favour again.
- *
- * If se was not a buddy, clear the buddies because neither
- * was elegible to run, let them earn it again.
- *
- * IOW. unconditionally clear buddies.
- */
- __clear_buddies(cfs_rq, NULL);
set_next_entity(cfs_rq, se);
cfs_rq = group_cfs_rq(se);
} while (cfs_rq);
return 0;
}
+
+static void rq_online_fair(struct rq *rq)
+{
+ update_sysctl();
+}
+
+static void rq_offline_fair(struct rq *rq)
+{
+ update_sysctl();
+}
+
#endif /* CONFIG_SMP */
/*
}
/*
- * Share the fairness runtime between parent and child, thus the
- * total amount of pressure for CPU stays equal - new tasks
- * get a chance to run but frequent forkers are not allowed to
- * monopolize the CPU. Note: the parent runqueue is locked,
- * the child is not running yet.
+ * called on fork with the child task as argument from the parent's context
+ * - child not yet on the tasklist
+ * - preemption disabled
*/
-static void task_new_fair(struct rq *rq, struct task_struct *p)
+static void task_fork_fair(struct task_struct *p)
{
- struct cfs_rq *cfs_rq = task_cfs_rq(p);
+ struct cfs_rq *cfs_rq = task_cfs_rq(current);
struct sched_entity *se = &p->se, *curr = cfs_rq->curr;
int this_cpu = smp_processor_id();
+ struct rq *rq = this_rq();
+ unsigned long flags;
- sched_info_queued(p);
+ raw_spin_lock_irqsave(&rq->lock, flags);
+
+ if (unlikely(task_cpu(p) != this_cpu))
+ __set_task_cpu(p, this_cpu);
update_curr(cfs_rq);
+
if (curr)
se->vruntime = curr->vruntime;
place_entity(cfs_rq, se, 1);
- /* 'curr' will be NULL if the child belongs to a different group */
- if (sysctl_sched_child_runs_first && this_cpu == task_cpu(p) &&
- curr && entity_before(curr, se)) {
+ if (sysctl_sched_child_runs_first && curr && entity_before(curr, se)) {
/*
* Upon rescheduling, sched_class::put_prev_task() will place
* 'current' within the tree based on its new key value.
resched_task(rq->curr);
}
- enqueue_task_fair(rq, p, 0);
+ se->vruntime -= cfs_rq->min_vruntime;
+
+ raw_spin_unlock_irqrestore(&rq->lock, flags);
}
/*
}
#ifdef CONFIG_FAIR_GROUP_SCHED
-static void moved_group_fair(struct task_struct *p)
+static void moved_group_fair(struct task_struct *p, int on_rq)
{
struct cfs_rq *cfs_rq = task_cfs_rq(p);
update_curr(cfs_rq);
- place_entity(cfs_rq, &p->se, 1);
+ if (!on_rq)
+ place_entity(cfs_rq, &p->se, 1);
}
#endif
-unsigned int get_rr_interval_fair(struct task_struct *task)
+unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task)
{
struct sched_entity *se = &task->se;
- unsigned long flags;
- struct rq *rq;
unsigned int rr_interval = 0;
/*
* Time slice is 0 for SCHED_OTHER tasks that are on an otherwise
* idle runqueue:
*/
- rq = task_rq_lock(task, &flags);
if (rq->cfs.load.weight)
rr_interval = NS_TO_JIFFIES(sched_slice(&rq->cfs, se));
- task_rq_unlock(rq, &flags);
return rr_interval;
}
.load_balance = load_balance_fair,
.move_one_task = move_one_task_fair,
+ .rq_online = rq_online_fair,
+ .rq_offline = rq_offline_fair,
+
+ .task_waking = task_waking_fair,
#endif
.set_curr_task = set_curr_task_fair,
.task_tick = task_tick_fair,
- .task_new = task_new_fair,
+ .task_fork = task_fork_fair,
.prio_changed = prio_changed_fair,
.switched_to = switched_to_fair,
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff