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authorLinus Torvalds <torvalds@linux-foundation.org>2012-03-20 10:31:44 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-03-20 10:31:44 -0700
commit2ba68940c893c8f0bfc8573c041254251bb6aeab (patch)
treefa83ebb01d32abd98123fa28f9f6f0b3eaeee25d /kernel
parent9c2b957db1772ebf942ae7a9346b14eba6c8ca66 (diff)
parent600e145882802d6ccbfe2c4aea243d97caeb91a9 (diff)
downloadlinux-2ba68940c893c8f0bfc8573c041254251bb6aeab.tar.bz2
Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler changes for v3.4 from Ingo Molnar * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits) printk: Make it compile with !CONFIG_PRINTK sched/x86: Fix overflow in cyc2ns_offset sched: Fix nohz load accounting -- again! sched: Update yield() docs printk/sched: Introduce special printk_sched() for those awkward moments sched/nohz: Correctly initialize 'next_balance' in 'nohz' idle balancer sched: Cleanup cpu_active madness sched: Fix load-balance wreckage sched: Clean up parameter passing of proc_sched_autogroup_set_nice() sched: Ditch per cgroup task lists for load-balancing sched: Rename load-balancing fields sched: Move load-balancing arguments into helper struct sched/rt: Do not submit new work when PI-blocked sched/rt: Prevent idle task boosting sched/wait: Add __wake_up_all_locked() API sched/rt: Document scheduler related skip-resched-check sites sched/rt: Use schedule_preempt_disabled() sched/rt: Add schedule_preempt_disabled() sched/rt: Do not throttle when PI boosting sched/rt: Keep period timer ticking when rt throttling is active ...
Diffstat (limited to 'kernel')
-rw-r--r--kernel/mutex.c4
-rw-r--r--kernel/printk.c40
-rw-r--r--kernel/sched/auto_group.c12
-rw-r--r--kernel/sched/core.c129
-rw-r--r--kernel/sched/debug.c1
-rw-r--r--kernel/sched/fair.c392
-rw-r--r--kernel/sched/rt.c43
-rw-r--r--kernel/sched/sched.h15
-rw-r--r--kernel/sched/stats.c4
-rw-r--r--kernel/softirq.c8
10 files changed, 348 insertions, 300 deletions
diff --git a/kernel/mutex.c b/kernel/mutex.c
index 89096dd8786f..a307cc9c9526 100644
--- a/kernel/mutex.c
+++ b/kernel/mutex.c
@@ -240,9 +240,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
/* didn't get the lock, go to sleep: */
spin_unlock_mutex(&lock->wait_lock, flags);
- preempt_enable_no_resched();
- schedule();
- preempt_disable();
+ schedule_preempt_disabled();
spin_lock_mutex(&lock->wait_lock, flags);
}
diff --git a/kernel/printk.c b/kernel/printk.c
index 0b3ea2cbd5fb..b663c2c95d39 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -1216,13 +1216,27 @@ int is_console_locked(void)
return console_locked;
}
+/*
+ * Delayed printk facility, for scheduler-internal messages:
+ */
+#define PRINTK_BUF_SIZE 512
+
+#define PRINTK_PENDING_WAKEUP 0x01
+#define PRINTK_PENDING_SCHED 0x02
+
static DEFINE_PER_CPU(int, printk_pending);
+static DEFINE_PER_CPU(char [PRINTK_BUF_SIZE], printk_sched_buf);
void printk_tick(void)
{
if (__this_cpu_read(printk_pending)) {
- __this_cpu_write(printk_pending, 0);
- wake_up_interruptible(&log_wait);
+ int pending = __this_cpu_xchg(printk_pending, 0);
+ if (pending & PRINTK_PENDING_SCHED) {
+ char *buf = __get_cpu_var(printk_sched_buf);
+ printk(KERN_WARNING "[sched_delayed] %s", buf);
+ }
+ if (pending & PRINTK_PENDING_WAKEUP)
+ wake_up_interruptible(&log_wait);
}
}
@@ -1236,7 +1250,7 @@ int printk_needs_cpu(int cpu)
void wake_up_klogd(void)
{
if (waitqueue_active(&log_wait))
- this_cpu_write(printk_pending, 1);
+ this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP);
}
/**
@@ -1629,6 +1643,26 @@ late_initcall(printk_late_init);
#if defined CONFIG_PRINTK
+int printk_sched(const char *fmt, ...)
+{
+ unsigned long flags;
+ va_list args;
+ char *buf;
+ int r;
+
+ local_irq_save(flags);
+ buf = __get_cpu_var(printk_sched_buf);
+
+ va_start(args, fmt);
+ r = vsnprintf(buf, PRINTK_BUF_SIZE, fmt, args);
+ va_end(args);
+
+ __this_cpu_or(printk_pending, PRINTK_PENDING_SCHED);
+ local_irq_restore(flags);
+
+ return r;
+}
+
/*
* printk rate limiting, lifted from the networking subsystem.
*
diff --git a/kernel/sched/auto_group.c b/kernel/sched/auto_group.c
index e8a1f83ee0e7..0984a21076a3 100644
--- a/kernel/sched/auto_group.c
+++ b/kernel/sched/auto_group.c
@@ -195,20 +195,20 @@ __setup("noautogroup", setup_autogroup);
#ifdef CONFIG_PROC_FS
-int proc_sched_autogroup_set_nice(struct task_struct *p, int *nice)
+int proc_sched_autogroup_set_nice(struct task_struct *p, int nice)
{
static unsigned long next = INITIAL_JIFFIES;
struct autogroup *ag;
int err;
- if (*nice < -20 || *nice > 19)
+ if (nice < -20 || nice > 19)
return -EINVAL;
- err = security_task_setnice(current, *nice);
+ err = security_task_setnice(current, nice);
if (err)
return err;
- if (*nice < 0 && !can_nice(current, *nice))
+ if (nice < 0 && !can_nice(current, nice))
return -EPERM;
/* this is a heavy operation taking global locks.. */
@@ -219,9 +219,9 @@ int proc_sched_autogroup_set_nice(struct task_struct *p, int *nice)
ag = autogroup_task_get(p);
down_write(&ag->lock);
- err = sched_group_set_shares(ag->tg, prio_to_weight[*nice + 20]);
+ err = sched_group_set_shares(ag->tg, prio_to_weight[nice + 20]);
if (!err)
- ag->nice = *nice;
+ ag->nice = nice;
up_write(&ag->lock);
autogroup_kref_put(ag);
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 6c41ba49767a..d2bd4647586c 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1284,7 +1284,7 @@ static int select_fallback_rq(int cpu, struct task_struct *p)
* leave kernel.
*/
if (p->mm && printk_ratelimit()) {
- printk(KERN_INFO "process %d (%s) no longer affine to cpu%d\n",
+ printk_sched("process %d (%s) no longer affine to cpu%d\n",
task_pid_nr(p), p->comm, cpu);
}
@@ -1507,7 +1507,7 @@ static int ttwu_activate_remote(struct task_struct *p, int wake_flags)
}
#endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */
-static inline int ttwu_share_cache(int this_cpu, int that_cpu)
+bool cpus_share_cache(int this_cpu, int that_cpu)
{
return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu);
}
@@ -1518,7 +1518,7 @@ static void ttwu_queue(struct task_struct *p, int cpu)
struct rq *rq = cpu_rq(cpu);
#if defined(CONFIG_SMP)
- if (sched_feat(TTWU_QUEUE) && !ttwu_share_cache(smp_processor_id(), cpu)) {
+ if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) {
sched_clock_cpu(cpu); /* sync clocks x-cpu */
ttwu_queue_remote(p, cpu);
return;
@@ -2266,13 +2266,10 @@ calc_load_n(unsigned long load, unsigned long exp,
* Once we've updated the global active value, we need to apply the exponential
* weights adjusted to the number of cycles missed.
*/
-static void calc_global_nohz(unsigned long ticks)
+static void calc_global_nohz(void)
{
long delta, active, n;
- if (time_before(jiffies, calc_load_update))
- return;
-
/*
* If we crossed a calc_load_update boundary, make sure to fold
* any pending idle changes, the respective CPUs might have
@@ -2284,31 +2281,25 @@ static void calc_global_nohz(unsigned long ticks)
atomic_long_add(delta, &calc_load_tasks);
/*
- * If we were idle for multiple load cycles, apply them.
+ * It could be the one fold was all it took, we done!
*/
- if (ticks >= LOAD_FREQ) {
- n = ticks / LOAD_FREQ;
+ if (time_before(jiffies, calc_load_update + 10))
+ return;
- active = atomic_long_read(&calc_load_tasks);
- active = active > 0 ? active * FIXED_1 : 0;
+ /*
+ * Catch-up, fold however many we are behind still
+ */
+ delta = jiffies - calc_load_update - 10;
+ n = 1 + (delta / LOAD_FREQ);
- avenrun[0] = calc_load_n(avenrun[0], EXP_1, active, n);
- avenrun[1] = calc_load_n(avenrun[1], EXP_5, active, n);
- avenrun[2] = calc_load_n(avenrun[2], EXP_15, active, n);
+ active = atomic_long_read(&calc_load_tasks);
+ active = active > 0 ? active * FIXED_1 : 0;
- calc_load_update += n * LOAD_FREQ;
- }
+ avenrun[0] = calc_load_n(avenrun[0], EXP_1, active, n);
+ avenrun[1] = calc_load_n(avenrun[1], EXP_5, active, n);
+ avenrun[2] = calc_load_n(avenrun[2], EXP_15, active, n);
- /*
- * Its possible the remainder of the above division also crosses
- * a LOAD_FREQ period, the regular check in calc_global_load()
- * which comes after this will take care of that.
- *
- * Consider us being 11 ticks before a cycle completion, and us
- * sleeping for 4*LOAD_FREQ + 22 ticks, then the above code will
- * age us 4 cycles, and the test in calc_global_load() will
- * pick up the final one.
- */
+ calc_load_update += n * LOAD_FREQ;
}
#else
void calc_load_account_idle(struct rq *this_rq)
@@ -2320,7 +2311,7 @@ static inline long calc_load_fold_idle(void)
return 0;
}
-static void calc_global_nohz(unsigned long ticks)
+static void calc_global_nohz(void)
{
}
#endif
@@ -2348,8 +2339,6 @@ void calc_global_load(unsigned long ticks)
{
long active;
- calc_global_nohz(ticks);
-
if (time_before(jiffies, calc_load_update + 10))
return;
@@ -2361,6 +2350,16 @@ void calc_global_load(unsigned long ticks)
avenrun[2] = calc_load(avenrun[2], EXP_15, active);
calc_load_update += LOAD_FREQ;
+
+ /*
+ * Account one period with whatever state we found before
+ * folding in the nohz state and ageing the entire idle period.
+ *
+ * This avoids loosing a sample when we go idle between
+ * calc_load_account_active() (10 ticks ago) and now and thus
+ * under-accounting.
+ */
+ calc_global_nohz();
}
/*
@@ -3220,14 +3219,14 @@ need_resched:
post_schedule(rq);
- preempt_enable_no_resched();
+ sched_preempt_enable_no_resched();
if (need_resched())
goto need_resched;
}
static inline void sched_submit_work(struct task_struct *tsk)
{
- if (!tsk->state)
+ if (!tsk->state || tsk_is_pi_blocked(tsk))
return;
/*
* If we are going to sleep and we have plugged IO queued,
@@ -3246,6 +3245,18 @@ asmlinkage void __sched schedule(void)
}
EXPORT_SYMBOL(schedule);
+/**
+ * schedule_preempt_disabled - called with preemption disabled
+ *
+ * Returns with preemption disabled. Note: preempt_count must be 1
+ */
+void __sched schedule_preempt_disabled(void)
+{
+ sched_preempt_enable_no_resched();
+ schedule();
+ preempt_disable();
+}
+
#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
static inline bool owner_running(struct mutex *lock, struct task_struct *owner)
@@ -3406,9 +3417,9 @@ EXPORT_SYMBOL(__wake_up);
/*
* Same as __wake_up but called with the spinlock in wait_queue_head_t held.
*/
-void __wake_up_locked(wait_queue_head_t *q, unsigned int mode)
+void __wake_up_locked(wait_queue_head_t *q, unsigned int mode, int nr)
{
- __wake_up_common(q, mode, 1, 0, NULL);
+ __wake_up_common(q, mode, nr, 0, NULL);
}
EXPORT_SYMBOL_GPL(__wake_up_locked);
@@ -3767,6 +3778,24 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
rq = __task_rq_lock(p);
+ /*
+ * Idle task boosting is a nono in general. There is one
+ * exception, when PREEMPT_RT and NOHZ is active:
+ *
+ * The idle task calls get_next_timer_interrupt() and holds
+ * the timer wheel base->lock on the CPU and another CPU wants
+ * to access the timer (probably to cancel it). We can safely
+ * ignore the boosting request, as the idle CPU runs this code
+ * with interrupts disabled and will complete the lock
+ * protected section without being interrupted. So there is no
+ * real need to boost.
+ */
+ if (unlikely(p == rq->idle)) {
+ WARN_ON(p != rq->curr);
+ WARN_ON(p->pi_blocked_on);
+ goto out_unlock;
+ }
+
trace_sched_pi_setprio(p, prio);
oldprio = p->prio;
prev_class = p->sched_class;
@@ -3790,11 +3819,10 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
enqueue_task(rq, p, oldprio < prio ? ENQUEUE_HEAD : 0);
check_class_changed(rq, p, prev_class, oldprio);
+out_unlock:
__task_rq_unlock(rq);
}
-
#endif
-
void set_user_nice(struct task_struct *p, long nice)
{
int old_prio, delta, on_rq;
@@ -4474,7 +4502,7 @@ SYSCALL_DEFINE0(sched_yield)
__release(rq->lock);
spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
do_raw_spin_unlock(&rq->lock);
- preempt_enable_no_resched();
+ sched_preempt_enable_no_resched();
schedule();
@@ -4548,8 +4576,24 @@ EXPORT_SYMBOL(__cond_resched_softirq);
/**
* yield - yield the current processor to other threads.
*
- * This is a shortcut for kernel-space yielding - it marks the
- * thread runnable and calls sys_sched_yield().
+ * Do not ever use this function, there's a 99% chance you're doing it wrong.
+ *
+ * The scheduler is at all times free to pick the calling task as the most
+ * eligible task to run, if removing the yield() call from your code breaks
+ * it, its already broken.
+ *
+ * Typical broken usage is:
+ *
+ * while (!event)
+ * yield();
+ *
+ * where one assumes that yield() will let 'the other' process run that will
+ * make event true. If the current task is a SCHED_FIFO task that will never
+ * happen. Never use yield() as a progress guarantee!!
+ *
+ * If you want to use yield() to wait for something, use wait_event().
+ * If you want to use yield() to be 'nice' for others, use cond_resched().
+ * If you still want to use yield(), do not!
*/
void __sched yield(void)
{
@@ -5381,7 +5425,7 @@ static int __cpuinit sched_cpu_active(struct notifier_block *nfb,
unsigned long action, void *hcpu)
{
switch (action & ~CPU_TASKS_FROZEN) {
- case CPU_ONLINE:
+ case CPU_STARTING:
case CPU_DOWN_FAILED:
set_cpu_active((long)hcpu, true);
return NOTIFY_OK;
@@ -5753,7 +5797,7 @@ static void destroy_sched_domains(struct sched_domain *sd, int cpu)
*
* Also keep a unique ID per domain (we use the first cpu number in
* the cpumask of the domain), this allows us to quickly tell if
- * two cpus are in the same cache domain, see ttwu_share_cache().
+ * two cpus are in the same cache domain, see cpus_share_cache().
*/
DEFINE_PER_CPU(struct sched_domain *, sd_llc);
DEFINE_PER_CPU(int, sd_llc_id);
@@ -6930,6 +6974,9 @@ void __init sched_init(void)
rq->online = 0;
rq->idle_stamp = 0;
rq->avg_idle = 2*sysctl_sched_migration_cost;
+
+ INIT_LIST_HEAD(&rq->cfs_tasks);
+
rq_attach_root(rq, &def_root_domain);
#ifdef CONFIG_NO_HZ
rq->nohz_flags = 0;
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 2a075e10004b..09acaa15161d 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -288,7 +288,6 @@ static void print_cpu(struct seq_file *m, int cpu)
P(yld_count);
- P(sched_switch);
P(sched_count);
P(sched_goidle);
#ifdef CONFIG_SMP
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index fd974faf467d..94340c7544a9 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -776,29 +776,16 @@ update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
* Scheduling class queueing methods:
*/
-#if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED
-static void
-add_cfs_task_weight(struct cfs_rq *cfs_rq, unsigned long weight)
-{
- cfs_rq->task_weight += weight;
-}
-#else
-static inline void
-add_cfs_task_weight(struct cfs_rq *cfs_rq, unsigned long weight)
-{
-}
-#endif
-
static void
account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
update_load_add(&cfs_rq->load, se->load.weight);
if (!parent_entity(se))
update_load_add(&rq_of(cfs_rq)->load, se->load.weight);
- if (entity_is_task(se)) {
- add_cfs_task_weight(cfs_rq, se->load.weight);
- list_add(&se->group_node, &cfs_rq->tasks);
- }
+#ifdef CONFIG_SMP
+ if (entity_is_task(se))
+ list_add_tail(&se->group_node, &rq_of(cfs_rq)->cfs_tasks);
+#endif
cfs_rq->nr_running++;
}
@@ -808,10 +795,8 @@ account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
update_load_sub(&cfs_rq->load, se->load.weight);
if (!parent_entity(se))
update_load_sub(&rq_of(cfs_rq)->load, se->load.weight);
- if (entity_is_task(se)) {
- add_cfs_task_weight(cfs_rq, -se->load.weight);
+ if (entity_is_task(se))
list_del_init(&se->group_node);
- }
cfs_rq->nr_running--;
}
@@ -2672,8 +2657,6 @@ static int select_idle_sibling(struct task_struct *p, int target)
/*
* Otherwise, iterate the domains and find an elegible idle cpu.
*/
- rcu_read_lock();
-
sd = rcu_dereference(per_cpu(sd_llc, target));
for_each_lower_domain(sd) {
sg = sd->groups;
@@ -2695,8 +2678,6 @@ next:
} while (sg != sd->groups);
}
done:
- rcu_read_unlock();
-
return target;
}
@@ -2922,7 +2903,7 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_
return;
/*
- * This is possible from callers such as pull_task(), in which we
+ * This is possible from callers such as move_task(), in which we
* unconditionally check_prempt_curr() after an enqueue (which may have
* lead to a throttle). This both saves work and prevents false
* next-buddy nomination below.
@@ -3086,17 +3067,39 @@ static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preemp
* Fair scheduling class load-balancing methods:
*/
+static unsigned long __read_mostly max_load_balance_interval = HZ/10;
+
+#define LBF_ALL_PINNED 0x01
+#define LBF_NEED_BREAK 0x02
+
+struct lb_env {
+ struct sched_domain *sd;
+
+ int src_cpu;
+ struct rq *src_rq;
+
+ int dst_cpu;
+ struct rq *dst_rq;
+
+ enum cpu_idle_type idle;
+ long load_move;
+ unsigned int flags;
+
+ unsigned int loop;
+ unsigned int loop_break;
+ unsigned int loop_max;
+};
+
/*
- * pull_task - move a task from a remote runqueue to the local runqueue.
+ * move_task - move a task from one runqueue to another runqueue.
* Both runqueues must be locked.
*/
-static void pull_task(struct rq *src_rq, struct task_struct *p,
- struct rq *this_rq, int this_cpu)
+static void move_task(struct task_struct *p, struct lb_env *env)
{
- deactivate_task(src_rq, p, 0);
- set_task_cpu(p, this_cpu);
- activate_task(this_rq, p, 0);
- check_preempt_curr(this_rq, p, 0);
+ deactivate_task(env->src_rq, p, 0);
+ set_task_cpu(p, env->dst_cpu);
+ activate_task(env->dst_rq, p, 0);
+ check_preempt_curr(env->dst_rq, p, 0);
}
/*
@@ -3131,19 +3134,11 @@ task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)
return delta < (s64)sysctl_sched_migration_cost;
}
-#define LBF_ALL_PINNED 0x01
-#define LBF_NEED_BREAK 0x02 /* clears into HAD_BREAK */
-#define LBF_HAD_BREAK 0x04
-#define LBF_HAD_BREAKS 0x0C /* count HAD_BREAKs overflows into ABORT */
-#define LBF_ABORT 0x10
-
/*
* can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
*/
static
-int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
- struct sched_domain *sd, enum cpu_idle_type idle,
- int *lb_flags)
+int can_migrate_task(struct task_struct *p, struct lb_env *env)
{
int tsk_cache_hot = 0;
/*
@@ -3152,13 +3147,13 @@ int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
* 2) cannot be migrated to this CPU due to cpus_allowed, or
* 3) are cache-hot on their current CPU.
*/
- if (!cpumask_test_cpu(this_cpu, tsk_cpus_allowed(p))) {
+ if (!cpumask_test_cpu(env->dst_cpu, tsk_cpus_allowed(p))) {
schedstat_inc(p, se.statistics.nr_failed_migrations_affine);
return 0;
}
- *lb_flags &= ~LBF_ALL_PINNED;
+ env->flags &= ~LBF_ALL_PINNED;
- if (task_running(rq, p)) {
+ if (task_running(env->src_rq, p)) {
schedstat_inc(p, se.statistics.nr_failed_migrations_running);
return 0;
}
@@ -3169,12 +3164,12 @@ int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
* 2) too many balance attempts have failed.
*/
- tsk_cache_hot = task_hot(p, rq->clock_task, sd);
+ tsk_cache_hot = task_hot(p, env->src_rq->clock_task, env->sd);
if (!tsk_cache_hot ||
- sd->nr_balance_failed > sd->cache_nice_tries) {
+ env->sd->nr_balance_failed > env->sd->cache_nice_tries) {
#ifdef CONFIG_SCHEDSTATS
if (tsk_cache_hot) {
- schedstat_inc(sd, lb_hot_gained[idle]);
+ schedstat_inc(env->sd, lb_hot_gained[env->idle]);
schedstat_inc(p, se.statistics.nr_forced_migrations);
}
#endif
@@ -3195,65 +3190,80 @@ int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
*
* Called with both runqueues locked.
*/
-static int
-move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest,
- struct sched_domain *sd, enum cpu_idle_type idle)
+static int move_one_task(struct lb_env *env)
{
struct task_struct *p, *n;
- struct cfs_rq *cfs_rq;
- int pinned = 0;
- for_each_leaf_cfs_rq(busiest, cfs_rq) {
- list_for_each_entry_safe(p, n, &cfs_rq->tasks, se.group_node) {
- if (throttled_lb_pair(task_group(p),
- busiest->cpu, this_cpu))
- break;
+ list_for_each_entry_safe(p, n, &env->src_rq->cfs_tasks, se.group_node) {
+ if (throttled_lb_pair(task_group(p), env->src_rq->cpu, env->dst_cpu))
+ continue;
- if (!can_migrate_task(p, busiest, this_cpu,
- sd, idle, &pinned))
- continue;
+ if (!can_migrate_task(p, env))
+ continue;
- pull_task(busiest, p, this_rq, this_cpu);
- /*
- * Right now, this is only the second place pull_task()
- * is called, so we can safely collect pull_task()
- * stats here rather than inside pull_task().
- */
- schedstat_inc(sd, lb_gained[idle]);
- return 1;
- }
+ move_task(p, env);
+ /*
+ * Right now, this is only the second place move_task()
+ * is called, so we can safely collect move_task()
+ * stats here rather than inside move_task().
+ */
+ schedstat_inc(env->sd, lb_gained[env->idle]);
+ return 1;
}
-
return 0;
}
-static unsigned long
-balance_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
- unsigned long max_load_move, struct sched_domain *sd,
- enum cpu_idle_type idle, int *lb_flags,
- struct cfs_rq *busiest_cfs_rq)
+static unsigned long task_h_load(struct task_struct *p);
+
+/*
+ * move_tasks tries to move up to load_move weighted load from busiest to
+ * this_rq, as part of a balancing operation within domain "sd".
+ * Returns 1 if successful and 0 otherwise.
+ *
+ * Called with both runqueues locked.
+ */
+static int move_tasks(struct lb_env *env)
{
- int loops = 0, pulled = 0;
- long rem_load_move = max_load_move;
- struct task_struct *p, *n;
+ struct list_head *tasks = &env->src_rq->cfs_tasks;
+ struct task_struct *p;
+ unsigned long load;
+ int pulled = 0;
+
+ if (env->load_move <= 0)
+ return 0;
- if (max_load_move == 0)
- goto out;
+ while (!list_empty(tasks)) {
+ p = list_first_entry(tasks, struct task_struct, se.group_node);
- list_for_each_entry_safe(p, n, &busiest_cfs_rq->tasks, se.group_node) {
- if (loops++ > sysctl_sched_nr_migrate) {
- *lb_flags |= LBF_NEED_BREAK;
+ env->loop++;
+ /* We've more or less seen every task there is, call it quits */
+ if (env->loop > env->loop_max)
+ break;
+
+ /* take a breather every nr_migrate tasks */
+ if (env->loop > env->loop_break) {
+ env->loop_break += sysctl_sched_nr_migrate;
+ env->flags |= LBF_NEED_BREAK;
break;
}
- if ((p->se.load.weight >> 1) > rem_load_move ||
- !can_migrate_task(p, busiest, this_cpu, sd, idle,
- lb_flags))
- continue;
+ if (throttled_lb_pair(task_group(p), env->src_cpu, env->dst_cpu))
+ goto next;
+
+ load = task_h_load(p);
+
+ if (load < 16 && !env->sd->nr_balance_failed)
+ goto next;
+
+ if ((load / 2) > env->load_move)
+ goto next;
- pull_task(busiest, p, this_rq, this_cpu);
+ if (!can_migrate_task(p, env))
+ goto next;
+
+ move_task(p, env);
pulled++;
- rem_load_move -= p->se.load.weight;
+ env->load_move -= load;
#ifdef CONFIG_PREEMPT
/*
@@ -3261,28 +3271,30 @@ balance_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
* kernels will stop after the first task is pulled to minimize
* the critical section.
*/
- if (idle == CPU_NEWLY_IDLE) {
- *lb_flags |= LBF_ABORT;
+ if (env->idle == CPU_NEWLY_IDLE)
break;
- }
#endif
/*
* We only want to steal up to the prescribed amount of
* weighted load.
*/
- if (rem_load_move <= 0)
+ if (env->load_move <= 0)
break;
+
+ continue;
+next:
+ list_move_tail(&p->se.group_node, tasks);
}
-out:
+
/*
- * Right now, this is one of only two places pull_task() is called,
- * so we can safely collect pull_task() stats here rather than
- * inside pull_task().
+ * Right now, this is one of only two places move_task() is called,
+ * so we can safely collect move_task() stats here rather than
+ * inside move_task().
*/
- schedstat_add(sd, lb_gained[idle], pulled);
+ schedstat_add(env->sd, lb_gained[env->idle], pulled);
- return max_load_move - rem_load_move;
+ return pulled;
}
#ifdef CONFIG_FAIR_GROUP_SCHED
@@ -3362,113 +3374,35 @@ static int tg_load_down(struct task_group *tg, void *data)
static void update_h_load(long cpu)
{
+ rcu_read_lock();
walk_tg_tree(tg_load_down, tg_nop, (void *)cpu);
+ rcu_read_unlock();
}
-static unsigned long
-load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
- unsigned long max_load_move,
- struct sched_domain *sd, enum cpu_idle_type idle,
- int *lb_flags)
+static unsigned long task_h_load(struct task_struct *p)
{
- long rem_load_move = max_load_move;
- struct cfs_rq *busiest_cfs_rq;
-
- rcu_read_lock();
- update_h_load(cpu_of(busiest));
-
- for_each_leaf_cfs_rq(busiest, busiest_cfs_rq) {
- unsigned long busiest_h_load = busiest_cfs_rq->h_load;
- unsigned long busiest_weight = busiest_cfs_rq->load.weight;
- u64 rem_load, moved_load;
-
- if (*lb_flags & (LBF_NEED_BREAK|LBF_ABORT))
- break;
-
- /*
- * empty group or part of a throttled hierarchy
- */
- if (!busiest_cfs_rq->task_weight ||
- throttled_lb_pair(busiest_cfs_rq->tg, cpu_of(busiest), this_cpu))
- continue;
-
- rem_load = (u64)rem_load_move * busiest_weight;
- rem_load = div_u64(rem_load, busiest_h_load + 1);
-
- moved_load = balance_tasks(this_rq, this_cpu, busiest,
- rem_load, sd, idle, lb_flags,
- busiest_cfs_rq);
-
- if (!moved_load)
- continue;
+ struct cfs_rq *cfs_rq = task_cfs_rq(p);
+ unsigned long load;
- moved_load *= busiest_h_load;
- moved_load = div_u64(moved_load, busiest_weight + 1);
+ load = p->se.load.weight;
+ load = div_u64(load * cfs_rq->h_load, cfs_rq->load.weight + 1);
- rem_load_move -= moved_load;
- if (rem_load_move < 0)
- break;
- }
- rcu_read_unlock();
-
- return max_load_move - rem_load_move;
+ return load;
}
#else
static inline void update_shares(int cpu)
{
}
-static unsigned long
-load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
- unsigned long max_load_move,
- struct sched_domain *sd, enum cpu_idle_type idle,
- int *lb_flags)
+static inline void update_h_load(long cpu)
{
- return balance_tasks(this_rq, this_cpu, busiest,
- max_load_move, sd, idle, lb_flags,
- &busiest->cfs);
}
-#endif
-/*
- * move_tasks tries to move up to max_load_move weighted load from busiest to
- * this_rq, as part of a balancing operation within domain "sd".
- * Returns 1 if successful and 0 otherwise.
- *
- * Called with both runqueues locked.
- */
-static int move_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
- unsigned long max_load_move,
- struct sched_domain *sd, enum cpu_idle_type idle,
- int *lb_flags)
+static unsigned long task_h_load(struct task_struct *p)
{
- unsigned long total_load_moved = 0, load_moved;
-
- do {
- load_moved = load_balance_fair(this_rq, this_cpu, busiest,
- max_load_move - total_load_moved,
- sd, idle, lb_flags);
-
- total_load_moved += load_moved;
-
- if (*lb_flags & (LBF_NEED_BREAK|LBF_ABORT))
- break;
-
-#ifdef CONFIG_PREEMPT
- /*
- * NEWIDLE balancing is a source of latency, so preemptible
- * kernels will stop after the first task is pulled to minimize
- * the critical section.
- */
- if (idle == CPU_NEWLY_IDLE && this_rq->nr_running) {
- *lb_flags |= LBF_ABORT;
- break;
- }
-#endif
- } while (load_moved && max_load_move > total_load_moved);
-
- return total_load_moved > 0;
+ return p->se.load.weight;
}
+#endif
/********** Helpers for find_busiest_group ************************/
/*
@@ -3778,6 +3712,11 @@ void update_group_power(struct sched_domain *sd, int cpu)
struct sched_domain *child = sd->child;
struct sched_group *group, *sdg = sd->groups;
unsigned long power;
+ unsigned long interval;
+
+ interval = msecs_to_jiffies(sd->balance_interval);
+ interval = clamp(interval, 1UL, max_load_balance_interval);
+ sdg->sgp->next_update = jiffies + interval;
if (!child) {
update_cpu_power(sd, cpu);
@@ -3885,12 +3824,15 @@ static inline void update_sg_lb_stats(struct sched_domain *sd,
* domains. In the newly idle case, we will allow all the cpu's
* to do the newly idle load balance.
*/
- if (idle != CPU_NEWLY_IDLE && local_group) {
- if (balance_cpu != this_cpu) {
- *balance = 0;
- return;
- }
- update_group_power(sd, this_cpu);
+ if (local_group) {
+ if (idle != CPU_NEWLY_IDLE) {
+ if (balance_cpu != this_cpu) {
+ *balance = 0;
+ return;
+ }
+ update_group_power(sd, this_cpu);
+ } else if (time_after_eq(jiffies, group->sgp->next_update))
+ update_group_power(sd, this_cpu);
}
/* Adjust by relative CPU power of the group */
@@ -4453,13 +4395,21 @@ static int load_balance(int this_cpu, struct rq *this_rq,
struct sched_domain *sd, enum cpu_idle_type idle,
int *balance)
{
- int ld_moved, lb_flags = 0, active_balance = 0;
+ int ld_moved, active_balance = 0;
struct sched_group *group;
unsigned long imbalance;
struct rq *busiest;
unsigned long flags;
struct cpumask *cpus = __get_cpu_var(load_balance_tmpmask);
+ struct lb_env env = {
+ .sd = sd,
+ .dst_cpu = this_cpu,
+ .dst_rq = this_rq,
+ .idle = idle,
+ .loop_break = sysctl_sched_nr_migrate,
+ };
+
cpumask_copy(cpus, cpu_active_mask);
schedstat_inc(sd, lb_count[idle]);
@@ -4494,32 +4444,34 @@ redo:
* still unbalanced. ld_moved simply stays zero, so it is
* correctly treated as an imbalance.
*/
- lb_flags |= LBF_ALL_PINNED;
+ env.flags |= LBF_ALL_PINNED;
+ env.load_move = imbalance;
+ env.src_cpu = busiest->cpu;
+ env.src_rq = busiest;
+ env.loop_max = busiest->nr_running;
+
+more_balance:
local_irq_save(flags);
double_rq_lock(this_rq, busiest);
- ld_moved = move_tasks(this_rq, this_cpu, busiest,
- imbalance, sd, idle, &lb_flags);
+ if (!env.loop)
+ update_h_load(env.src_cpu);
+ ld_moved += move_tasks(&env);
double_rq_unlock(this_rq, busiest);
local_irq_restore(flags);
+ if (env.flags & LBF_NEED_BREAK) {
+ env.flags &= ~LBF_NEED_BREAK;
+ goto more_balance;
+ }
+
/*
* some other cpu did the load balance for us.
*/
if (ld_moved && this_cpu != smp_processor_id())
resched_cpu(this_cpu);
- if (lb_flags & LBF_ABORT)
- goto out_balanced;
-
- if (lb_flags & LBF_NEED_BREAK) {
- lb_flags += LBF_HAD_BREAK - LBF_NEED_BREAK;
- if (lb_flags & LBF_ABORT)
- goto out_balanced;
- goto redo;
- }
-
/* All tasks on this runqueue were pinned by CPU affinity */
- if (unlikely(lb_flags & LBF_ALL_PINNED)) {
+ if (unlikely(env.flags & LBF_ALL_PINNED)) {
cpumask_clear_cpu(cpu_of(busiest), cpus);
if (!cpumask_empty(cpus))
goto redo;
@@ -4549,7 +4501,7 @@ redo:
tsk_cpus_allowed(busiest->curr))) {
raw_spin_unlock_irqrestore(&busiest->lock,
flags);
- lb_flags |= LBF_ALL_PINNED;
+ env.flags |= LBF_ALL_PINNED;
goto out_one_pinned;
}
@@ -4602,7 +4554,7 @@ out_balanced:
out_one_pinned:
/* tune up the balancing interval */
- if (((lb_flags & LBF_ALL_PINNED) &&
+ if (((env.flags & LBF_ALL_PINNED) &&
sd->balance_interval < MAX_PINNED_INTERVAL) ||
(sd->balance_interval < sd->max_interval))
sd->balance_interval *= 2;
@@ -4712,10 +4664,18 @@ static int active_load_balance_cpu_stop(void *data)
}
if (likely(sd)) {
+ struct lb_env env = {
+ .sd = sd,
+ .dst_cpu = target_cpu,
+ .dst_rq = target_rq,
+ .src_cpu = busiest_rq->cpu,
+ .src_rq = busiest_rq,
+ .idle = CPU_IDLE,
+ };
+
schedstat_inc(sd, alb_count);
- if (move_one_task(target_rq, target_cpu, busiest_rq,
- sd, CPU_IDLE))
+ if (move_one_task(&env))
schedstat_inc(sd, alb_pushed);
else
schedstat_inc(sd, alb_failed);
@@ -4947,8 +4907,6 @@ static int __cpuinit sched_ilb_notifier(struct notifier_block *nfb,
static DEFINE_SPINLOCK(balancing);
-static unsigned long __read_mostly max_load_balance_interval = HZ/10;
-
/*
* Scale the max load_balance interval with the number of CPUs in the system.
* This trades load-balance latency on larger machines for less cross talk.
@@ -5342,7 +5300,6 @@ static void set_curr_task_fair(struct rq *rq)
void init_cfs_rq(struct cfs_rq *cfs_rq)
{
cfs_rq->tasks_timeline = RB_ROOT;
- INIT_LIST_HEAD(&cfs_rq->tasks);
cfs_rq->min_vruntime = (u64)(-(1LL << 20));
#ifndef CONFIG_64BIT
cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime;
@@ -5614,6 +5571,7 @@ __init void init_sched_fair_class(void)
open_softirq(SCHED_SOFTIRQ, run_rebalance_domains);
#ifdef CONFIG_NO_HZ
+ nohz.next_balance = jiffies;
zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT);
cpu_notifier(sched_ilb_notifier, 0);
#endif
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index f42ae7fb5ec5..b60dad720173 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -778,12 +778,9 @@ static inline int balance_runtime(struct rt_rq *rt_rq)
static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
{
- int i, idle = 1;
+ int i, idle = 1, throttled = 0;
const struct cpumask *span;
- if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)
- return 1;
-
span = sched_rt_period_mask();
for_each_cpu(i, span) {
int enqueue = 0;
@@ -818,12 +815,17 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
if (!rt_rq_throttled(rt_rq))
enqueue = 1;
}
+ if (rt_rq->rt_throttled)
+ throttled = 1;
if (enqueue)
sched_rt_rq_enqueue(rt_rq);
raw_spin_unlock(&rq->lock);
}
+ if (!throttled && (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF))
+ return 1;
+
return idle;
}
@@ -855,8 +857,30 @@ static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
return 0;
if (rt_rq->rt_time > runtime) {
- rt_rq->rt_throttled = 1;
- printk_once(KERN_WARNING "sched: RT throttling activated\n");
+ struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
+
+ /*
+ * Don't actually throttle groups that have no runtime assigned
+ * but accrue some time due to boosting.
+ */
+ if (likely(rt_b->rt_runtime)) {
+ static bool once = false;
+
+ rt_rq->rt_throttled = 1;
+
+ if (!once) {
+ once = true;
+ printk_sched("sched: RT throttling activated\n");
+ }
+ } else {
+ /*
+ * In case we did anyway, make it go away,
+ * replenishment is a joke, since it will replenish us
+ * with exactly 0 ns.
+ */
+ rt_rq->rt_time = 0;
+ }
+
if (rt_rq_throttled(rt_rq)) {
sched_rt_rq_dequeue(rt_rq);
return 1;
@@ -884,7 +908,8 @@ static void update_curr_rt(struct rq *rq)
if (unlikely((s64)delta_exec < 0))
delta_exec = 0;
- schedstat_set(curr->se.statistics.exec_max, max(curr->se.statistics.exec_max, delta_exec));
+ schedstat_set(curr->se.statistics.exec_max,
+ max(curr->se.statistics.exec_max, delta_exec));
curr->se.sum_exec_runtime += delta_exec;
account_group_exec_runtime(curr, delta_exec);
@@ -1972,7 +1997,7 @@ static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
if (--p->rt.time_slice)
return;
- p->rt.time_slice = DEF_TIMESLICE;
+ p->rt.time_slice = RR_TIMESLICE;
/*
* Requeue to the end of queue if we are not the only element
@@ -2000,7 +2025,7 @@ static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
* Time slice is 0 for SCHED_FIFO tasks
*/
if (task->policy == SCHED_RR)
- return DEF_TIMESLICE;
+ return RR_TIMESLICE;
else
return 0;
}
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index b4cd6d8ea150..42b1f304b044 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -36,11 +36,7 @@ extern __read_mostly int scheduler_running;
/*
* These are the 'tuning knobs' of the scheduler:
- *
- * default timeslice is 100 msecs (used only for SCHED_RR tasks).
- * Timeslices get refilled after they expire.
*/
-#define DEF_TIMESLICE (100 * HZ / 1000)
/*
* single value that denotes runtime == period, ie unlimited time.
@@ -216,9 +212,6 @@ struct cfs_rq {
struct rb_root tasks_timeline;
struct rb_node *rb_leftmost;
- struct list_head tasks;
- struct list_head *balance_iterator;
-
/*
* 'curr' points to currently running entity on this cfs_rq.
* It is set to NULL otherwise (i.e when none are currently running).
@@ -246,11 +239,6 @@ struct cfs_rq {
#ifdef CONFIG_SMP
/*
- * the part of load.weight contributed by tasks
- */
- unsigned long task_weight;
-
- /*
* h_load = weight * f(tg)
*
* Where f(tg) is the recursive weight fraction assigned to
@@ -424,6 +412,8 @@ struct rq {
int cpu;
int online;
+ struct list_head cfs_tasks;
+
u64 rt_avg;
u64 age_stamp;
u64 idle_stamp;
@@ -462,7 +452,6 @@ struct rq {
unsigned int yld_count;
/* schedule() stats */
- unsigned int sched_switch;
unsigned int sched_count;
unsigned int sched_goidle;
diff --git a/kernel/sched/stats.c b/kernel/sched/stats.c
index 2a581ba8e190..903ffa9e8872 100644
--- a/kernel/sched/stats.c
+++ b/kernel/sched/stats.c
@@ -32,9 +32,9 @@ static int show_schedstat(struct seq_file *seq, void *v)
/* runqueue-specific stats */
seq_printf(seq,
- "cpu%d %u %u %u %u %u %u %llu %llu %lu",
+ "cpu%d %u 0 %u %u %u %u %llu %llu %lu",
cpu, rq->yld_count,
- rq->sched_switch, rq->sched_count, rq->sched_goidle,
+ rq->sched_count, rq->sched_goidle,
rq->ttwu_count, rq->ttwu_local,
rq->rq_cpu_time,
rq->rq_sched_info.run_delay, rq->rq_sched_info.pcount);
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 8afc6a8d4d7c..15352e0cbd5d 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -343,7 +343,7 @@ void irq_exit(void)
tick_nohz_irq_exit();
#endif
rcu_irq_exit();
- preempt_enable_no_resched();
+ sched_preempt_enable_no_resched();
}
/*
@@ -740,9 +740,7 @@ static int run_ksoftirqd(void * __bind_cpu)
while (!kthread_should_stop()) {
preempt_disable();
if (!local_softirq_pending()) {
- preempt_enable_no_resched();
- schedule();
- preempt_disable();
+ schedule_preempt_disabled();
}
__set_current_state(TASK_RUNNING);
@@ -757,7 +755,7 @@ static int run_ksoftirqd(void * __bind_cpu)
if (local_softirq_pending())
__do_softirq();
local_irq_enable();
- preempt_enable_no_resched();
+ sched_preempt_enable_no_resched();
cond_resched();
preempt_disable();
rcu_note_context_switch((long)__bind_cpu);