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-rw-r--r--kernel/sched.c284
1 files changed, 219 insertions, 65 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index 678335a8b39..1847a4456a2 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -168,15 +168,21 @@
*/
#define SCALE_PRIO(x, prio) \
- max(x * (MAX_PRIO - prio) / (MAX_USER_PRIO/2), MIN_TIMESLICE)
+ max(x * (MAX_PRIO - prio) / (MAX_USER_PRIO / 2), MIN_TIMESLICE)
-static unsigned int task_timeslice(task_t *p)
+static unsigned int static_prio_timeslice(int static_prio)
{
- if (p->static_prio < NICE_TO_PRIO(0))
- return SCALE_PRIO(DEF_TIMESLICE*4, p->static_prio);
+ if (static_prio < NICE_TO_PRIO(0))
+ return SCALE_PRIO(DEF_TIMESLICE * 4, static_prio);
else
- return SCALE_PRIO(DEF_TIMESLICE, p->static_prio);
+ return SCALE_PRIO(DEF_TIMESLICE, static_prio);
}
+
+static inline unsigned int task_timeslice(task_t *p)
+{
+ return static_prio_timeslice(p->static_prio);
+}
+
#define task_hot(p, now, sd) ((long long) ((now) - (p)->last_ran) \
< (long long) (sd)->cache_hot_time)
@@ -207,6 +213,7 @@ struct runqueue {
* remote CPUs use both these fields when doing load calculation.
*/
unsigned long nr_running;
+ unsigned long raw_weighted_load;
#ifdef CONFIG_SMP
unsigned long cpu_load[3];
#endif
@@ -662,6 +669,68 @@ static int effective_prio(task_t *p)
}
/*
+ * To aid in avoiding the subversion of "niceness" due to uneven distribution
+ * of tasks with abnormal "nice" values across CPUs the contribution that
+ * each task makes to its run queue's load is weighted according to its
+ * scheduling class and "nice" value. For SCHED_NORMAL tasks this is just a
+ * scaled version of the new time slice allocation that they receive on time
+ * slice expiry etc.
+ */
+
+/*
+ * Assume: static_prio_timeslice(NICE_TO_PRIO(0)) == DEF_TIMESLICE
+ * If static_prio_timeslice() is ever changed to break this assumption then
+ * this code will need modification
+ */
+#define TIME_SLICE_NICE_ZERO DEF_TIMESLICE
+#define LOAD_WEIGHT(lp) \
+ (((lp) * SCHED_LOAD_SCALE) / TIME_SLICE_NICE_ZERO)
+#define PRIO_TO_LOAD_WEIGHT(prio) \
+ LOAD_WEIGHT(static_prio_timeslice(prio))
+#define RTPRIO_TO_LOAD_WEIGHT(rp) \
+ (PRIO_TO_LOAD_WEIGHT(MAX_RT_PRIO) + LOAD_WEIGHT(rp))
+
+static void set_load_weight(task_t *p)
+{
+ if (rt_task(p)) {
+#ifdef CONFIG_SMP
+ if (p == task_rq(p)->migration_thread)
+ /*
+ * The migration thread does the actual balancing.
+ * Giving its load any weight will skew balancing
+ * adversely.
+ */
+ p->load_weight = 0;
+ else
+#endif
+ p->load_weight = RTPRIO_TO_LOAD_WEIGHT(p->rt_priority);
+ } else
+ p->load_weight = PRIO_TO_LOAD_WEIGHT(p->static_prio);
+}
+
+static inline void inc_raw_weighted_load(runqueue_t *rq, const task_t *p)
+{
+ rq->raw_weighted_load += p->load_weight;
+}
+
+static inline void dec_raw_weighted_load(runqueue_t *rq, const task_t *p)
+{
+ rq->raw_weighted_load -= p->load_weight;
+}
+
+static inline void inc_nr_running(task_t *p, runqueue_t *rq)
+{
+ rq->nr_running++;
+ inc_raw_weighted_load(rq, p);
+}
+
+static inline void dec_nr_running(task_t *p, runqueue_t *rq)
+{
+ rq->nr_running--;
+ dec_raw_weighted_load(rq, p);
+}
+
+/*
* __activate_task - move a task to the runqueue.
*/
static void __activate_task(task_t *p, runqueue_t *rq)
@@ -671,7 +740,7 @@ static void __activate_task(task_t *p, runqueue_t *rq)
if (batch_task(p))
target = rq->expired;
enqueue_task(p, target);
- rq->nr_running++;
+ inc_nr_running(p, rq);
}
/*
@@ -680,7 +749,7 @@ static void __activate_task(task_t *p, runqueue_t *rq)
static inline void __activate_idle_task(task_t *p, runqueue_t *rq)
{
enqueue_task_head(p, rq->active);
- rq->nr_running++;
+ inc_nr_running(p, rq);
}
static int recalc_task_prio(task_t *p, unsigned long long now)
@@ -804,7 +873,7 @@ static void activate_task(task_t *p, runqueue_t *rq, int local)
*/
static void deactivate_task(struct task_struct *p, runqueue_t *rq)
{
- rq->nr_running--;
+ dec_nr_running(p, rq);
dequeue_task(p, p->array);
p->array = NULL;
}
@@ -859,6 +928,12 @@ inline int task_curr(const task_t *p)
return cpu_curr(task_cpu(p)) == p;
}
+/* Used instead of source_load when we know the type == 0 */
+unsigned long weighted_cpuload(const int cpu)
+{
+ return cpu_rq(cpu)->raw_weighted_load;
+}
+
#ifdef CONFIG_SMP
typedef struct {
struct list_head list;
@@ -948,7 +1023,8 @@ void kick_process(task_t *p)
}
/*
- * Return a low guess at the load of a migration-source cpu.
+ * Return a low guess at the load of a migration-source cpu weighted
+ * according to the scheduling class and "nice" value.
*
* We want to under-estimate the load of migration sources, to
* balance conservatively.
@@ -956,24 +1032,36 @@ void kick_process(task_t *p)
static inline unsigned long source_load(int cpu, int type)
{
runqueue_t *rq = cpu_rq(cpu);
- unsigned long load_now = rq->nr_running * SCHED_LOAD_SCALE;
+
if (type == 0)
- return load_now;
+ return rq->raw_weighted_load;
- return min(rq->cpu_load[type-1], load_now);
+ return min(rq->cpu_load[type-1], rq->raw_weighted_load);
}
/*
- * Return a high guess at the load of a migration-target cpu
+ * Return a high guess at the load of a migration-target cpu weighted
+ * according to the scheduling class and "nice" value.
*/
static inline unsigned long target_load(int cpu, int type)
{
runqueue_t *rq = cpu_rq(cpu);
- unsigned long load_now = rq->nr_running * SCHED_LOAD_SCALE;
+
if (type == 0)
- return load_now;
+ return rq->raw_weighted_load;
- return max(rq->cpu_load[type-1], load_now);
+ return max(rq->cpu_load[type-1], rq->raw_weighted_load);
+}
+
+/*
+ * Return the average load per task on the cpu's run queue
+ */
+static inline unsigned long cpu_avg_load_per_task(int cpu)
+{
+ runqueue_t *rq = cpu_rq(cpu);
+ unsigned long n = rq->nr_running;
+
+ return n ? rq->raw_weighted_load / n : SCHED_LOAD_SCALE;
}
/*
@@ -1046,7 +1134,7 @@ find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
cpus_and(tmp, group->cpumask, p->cpus_allowed);
for_each_cpu_mask(i, tmp) {
- load = source_load(i, 0);
+ load = weighted_cpuload(i);
if (load < min_load || (load == min_load && i == this_cpu)) {
min_load = load;
@@ -1226,17 +1314,19 @@ static int try_to_wake_up(task_t *p, unsigned int state, int sync)
if (this_sd->flags & SD_WAKE_AFFINE) {
unsigned long tl = this_load;
+ unsigned long tl_per_task = cpu_avg_load_per_task(this_cpu);
+
/*
* If sync wakeup then subtract the (maximum possible)
* effect of the currently running task from the load
* of the current CPU:
*/
if (sync)
- tl -= SCHED_LOAD_SCALE;
+ tl -= current->load_weight;
if ((tl <= load &&
- tl + target_load(cpu, idx) <= SCHED_LOAD_SCALE) ||
- 100*(tl + SCHED_LOAD_SCALE) <= imbalance*load) {
+ tl + target_load(cpu, idx) <= tl_per_task) ||
+ 100*(tl + p->load_weight) <= imbalance*load) {
/*
* This domain has SD_WAKE_AFFINE and
* p is cache cold in this domain, and
@@ -1435,7 +1525,7 @@ void fastcall wake_up_new_task(task_t *p, unsigned long clone_flags)
list_add_tail(&p->run_list, &current->run_list);
p->array = current->array;
p->array->nr_active++;
- rq->nr_running++;
+ inc_nr_running(p, rq);
}
set_need_resched();
} else
@@ -1802,9 +1892,9 @@ void pull_task(runqueue_t *src_rq, prio_array_t *src_array, task_t *p,
runqueue_t *this_rq, prio_array_t *this_array, int this_cpu)
{
dequeue_task(p, src_array);
- src_rq->nr_running--;
+ dec_nr_running(p, src_rq);
set_task_cpu(p, this_cpu);
- this_rq->nr_running++;
+ inc_nr_running(p, this_rq);
enqueue_task(p, this_array);
p->timestamp = (p->timestamp - src_rq->timestamp_last_tick)
+ this_rq->timestamp_last_tick;
@@ -1852,24 +1942,27 @@ int can_migrate_task(task_t *p, runqueue_t *rq, int this_cpu,
}
/*
- * move_tasks tries to move up to max_nr_move tasks from busiest to this_rq,
- * as part of a balancing operation within "domain". Returns the number of
- * tasks moved.
+ * move_tasks tries to move up to max_nr_move tasks and max_load_move weighted
+ * load from busiest to this_rq, as part of a balancing operation within
+ * "domain". Returns the number of tasks moved.
*
* Called with both runqueues locked.
*/
static int move_tasks(runqueue_t *this_rq, int this_cpu, runqueue_t *busiest,
- unsigned long max_nr_move, struct sched_domain *sd,
- enum idle_type idle, int *all_pinned)
+ unsigned long max_nr_move, unsigned long max_load_move,
+ struct sched_domain *sd, enum idle_type idle,
+ int *all_pinned)
{
prio_array_t *array, *dst_array;
struct list_head *head, *curr;
int idx, pulled = 0, pinned = 0;
+ long rem_load_move;
task_t *tmp;
- if (max_nr_move == 0)
+ if (max_nr_move == 0 || max_load_move == 0)
goto out;
+ rem_load_move = max_load_move;
pinned = 1;
/*
@@ -1910,7 +2003,8 @@ skip_queue:
curr = curr->prev;
- if (!can_migrate_task(tmp, busiest, this_cpu, sd, idle, &pinned)) {
+ if (tmp->load_weight > rem_load_move ||
+ !can_migrate_task(tmp, busiest, this_cpu, sd, idle, &pinned)) {
if (curr != head)
goto skip_queue;
idx++;
@@ -1924,9 +2018,13 @@ skip_queue:
pull_task(busiest, array, tmp, this_rq, dst_array, this_cpu);
pulled++;
+ rem_load_move -= tmp->load_weight;
- /* We only want to steal up to the prescribed number of tasks. */
- if (pulled < max_nr_move) {
+ /*
+ * We only want to steal up to the prescribed number of tasks
+ * and the prescribed amount of weighted load.
+ */
+ if (pulled < max_nr_move && rem_load_move > 0) {
if (curr != head)
goto skip_queue;
idx++;
@@ -1947,7 +2045,7 @@ out:
/*
* find_busiest_group finds and returns the busiest CPU group within the
- * domain. It calculates and returns the number of tasks which should be
+ * domain. It calculates and returns the amount of weighted load which should be
* moved to restore balance via the imbalance parameter.
*/
static struct sched_group *
@@ -1957,9 +2055,13 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
struct sched_group *busiest = NULL, *this = NULL, *group = sd->groups;
unsigned long max_load, avg_load, total_load, this_load, total_pwr;
unsigned long max_pull;
+ unsigned long busiest_load_per_task, busiest_nr_running;
+ unsigned long this_load_per_task, this_nr_running;
int load_idx;
max_load = this_load = total_load = total_pwr = 0;
+ busiest_load_per_task = busiest_nr_running = 0;
+ this_load_per_task = this_nr_running = 0;
if (idle == NOT_IDLE)
load_idx = sd->busy_idx;
else if (idle == NEWLY_IDLE)
@@ -1971,13 +2073,16 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
unsigned long load;
int local_group;
int i;
+ unsigned long sum_nr_running, sum_weighted_load;
local_group = cpu_isset(this_cpu, group->cpumask);
/* Tally up the load of all CPUs in the group */
- avg_load = 0;
+ sum_weighted_load = sum_nr_running = avg_load = 0;
for_each_cpu_mask(i, group->cpumask) {
+ runqueue_t *rq = cpu_rq(i);
+
if (*sd_idle && !idle_cpu(i))
*sd_idle = 0;
@@ -1988,6 +2093,8 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
load = source_load(i, load_idx);
avg_load += load;
+ sum_nr_running += rq->nr_running;
+ sum_weighted_load += rq->raw_weighted_load;
}
total_load += avg_load;
@@ -1999,14 +2106,19 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
if (local_group) {
this_load = avg_load;
this = group;
- } else if (avg_load > max_load) {
+ this_nr_running = sum_nr_running;
+ this_load_per_task = sum_weighted_load;
+ } else if (avg_load > max_load &&
+ sum_nr_running > group->cpu_power / SCHED_LOAD_SCALE) {
max_load = avg_load;
busiest = group;
+ busiest_nr_running = sum_nr_running;
+ busiest_load_per_task = sum_weighted_load;
}
group = group->next;
} while (group != sd->groups);
- if (!busiest || this_load >= max_load || max_load <= SCHED_LOAD_SCALE)
+ if (!busiest || this_load >= max_load || busiest_nr_running == 0)
goto out_balanced;
avg_load = (SCHED_LOAD_SCALE * total_load) / total_pwr;
@@ -2015,6 +2127,7 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
100*max_load <= sd->imbalance_pct*this_load)
goto out_balanced;
+ busiest_load_per_task /= busiest_nr_running;
/*
* We're trying to get all the cpus to the average_load, so we don't
* want to push ourselves above the average load, nor do we wish to
@@ -2026,21 +2139,50 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
* by pulling tasks to us. Be careful of negative numbers as they'll
* appear as very large values with unsigned longs.
*/
+ if (max_load <= busiest_load_per_task)
+ goto out_balanced;
+
+ /*
+ * In the presence of smp nice balancing, certain scenarios can have
+ * max load less than avg load(as we skip the groups at or below
+ * its cpu_power, while calculating max_load..)
+ */
+ if (max_load < avg_load) {
+ *imbalance = 0;
+ goto small_imbalance;
+ }
/* Don't want to pull so many tasks that a group would go idle */
- max_pull = min(max_load - avg_load, max_load - SCHED_LOAD_SCALE);
+ max_pull = min(max_load - avg_load, max_load - busiest_load_per_task);
/* How much load to actually move to equalise the imbalance */
*imbalance = min(max_pull * busiest->cpu_power,
(avg_load - this_load) * this->cpu_power)
/ SCHED_LOAD_SCALE;
- if (*imbalance < SCHED_LOAD_SCALE) {
- unsigned long pwr_now = 0, pwr_move = 0;
+ /*
+ * if *imbalance is less than the average load per runnable task
+ * there is no gaurantee that any tasks will be moved so we'll have
+ * a think about bumping its value to force at least one task to be
+ * moved
+ */
+ if (*imbalance < busiest_load_per_task) {
+ unsigned long pwr_now, pwr_move;
unsigned long tmp;
+ unsigned int imbn;
+
+small_imbalance:
+ pwr_move = pwr_now = 0;
+ imbn = 2;
+ if (this_nr_running) {
+ this_load_per_task /= this_nr_running;
+ if (busiest_load_per_task > this_load_per_task)
+ imbn = 1;
+ } else
+ this_load_per_task = SCHED_LOAD_SCALE;
- if (max_load - this_load >= SCHED_LOAD_SCALE*2) {
- *imbalance = 1;
+ if (max_load - this_load >= busiest_load_per_task * imbn) {
+ *imbalance = busiest_load_per_task;
return busiest;
}
@@ -2050,35 +2192,34 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
* moving them.
*/
- pwr_now += busiest->cpu_power*min(SCHED_LOAD_SCALE, max_load);
- pwr_now += this->cpu_power*min(SCHED_LOAD_SCALE, this_load);
+ pwr_now += busiest->cpu_power *
+ min(busiest_load_per_task, max_load);
+ pwr_now += this->cpu_power *
+ min(this_load_per_task, this_load);
pwr_now /= SCHED_LOAD_SCALE;
/* Amount of load we'd subtract */
- tmp = SCHED_LOAD_SCALE*SCHED_LOAD_SCALE/busiest->cpu_power;
+ tmp = busiest_load_per_task*SCHED_LOAD_SCALE/busiest->cpu_power;
if (max_load > tmp)
- pwr_move += busiest->cpu_power*min(SCHED_LOAD_SCALE,
- max_load - tmp);
+ pwr_move += busiest->cpu_power *
+ min(busiest_load_per_task, max_load - tmp);
/* Amount of load we'd add */
if (max_load*busiest->cpu_power <
- SCHED_LOAD_SCALE*SCHED_LOAD_SCALE)
+ busiest_load_per_task*SCHED_LOAD_SCALE)
tmp = max_load*busiest->cpu_power/this->cpu_power;
else
- tmp = SCHED_LOAD_SCALE*SCHED_LOAD_SCALE/this->cpu_power;
- pwr_move += this->cpu_power*min(SCHED_LOAD_SCALE, this_load + tmp);
+ tmp = busiest_load_per_task*SCHED_LOAD_SCALE/this->cpu_power;
+ pwr_move += this->cpu_power*min(this_load_per_task, this_load + tmp);
pwr_move /= SCHED_LOAD_SCALE;
/* Move if we gain throughput */
if (pwr_move <= pwr_now)
goto out_balanced;
- *imbalance = 1;
- return busiest;
+ *imbalance = busiest_load_per_task;
}
- /* Get rid of the scaling factor, rounding down as we divide */
- *imbalance = *imbalance / SCHED_LOAD_SCALE;
return busiest;
out_balanced:
@@ -2091,18 +2232,21 @@ out_balanced:
* find_busiest_queue - find the busiest runqueue among the cpus in group.
*/
static runqueue_t *find_busiest_queue(struct sched_group *group,
- enum idle_type idle)
+ enum idle_type idle, unsigned long imbalance)
{
- unsigned long load, max_load = 0;
- runqueue_t *busiest = NULL;
+ unsigned long max_load = 0;
+ runqueue_t *busiest = NULL, *rqi;
int i;
for_each_cpu_mask(i, group->cpumask) {
- load = source_load(i, 0);
+ rqi = cpu_rq(i);
+
+ if (rqi->nr_running == 1 && rqi->raw_weighted_load > imbalance)
+ continue;
- if (load > max_load) {
- max_load = load;
- busiest = cpu_rq(i);
+ if (rqi->raw_weighted_load > max_load) {
+ max_load = rqi->raw_weighted_load;
+ busiest = rqi;
}
}
@@ -2115,6 +2259,7 @@ static runqueue_t *find_busiest_queue(struct sched_group *group,
*/
#define MAX_PINNED_INTERVAL 512
+#define minus_1_or_zero(n) ((n) > 0 ? (n) - 1 : 0)
/*
* Check this_cpu to ensure it is balanced within domain. Attempt to move
* tasks if there is an imbalance.
@@ -2142,7 +2287,7 @@ static int load_balance(int this_cpu, runqueue_t *this_rq,
goto out_balanced;
}
- busiest = find_busiest_queue(group, idle);
+ busiest = find_busiest_queue(group, idle, imbalance);
if (!busiest) {
schedstat_inc(sd, lb_nobusyq[idle]);
goto out_balanced;
@@ -2162,6 +2307,7 @@ static int load_balance(int this_cpu, runqueue_t *this_rq,
*/
double_rq_lock(this_rq, busiest);
nr_moved = move_tasks(this_rq, this_cpu, busiest,
+ minus_1_or_zero(busiest->nr_running),
imbalance, sd, idle, &all_pinned);
double_rq_unlock(this_rq, busiest);
@@ -2265,7 +2411,7 @@ static int load_balance_newidle(int this_cpu, runqueue_t *this_rq,
goto out_balanced;
}
- busiest = find_busiest_queue(group, NEWLY_IDLE);
+ busiest = find_busiest_queue(group, NEWLY_IDLE, imbalance);
if (!busiest) {
schedstat_inc(sd, lb_nobusyq[NEWLY_IDLE]);
goto out_balanced;
@@ -2280,6 +2426,7 @@ static int load_balance_newidle(int this_cpu, runqueue_t *this_rq,
/* Attempt to move tasks */
double_lock_balance(this_rq, busiest);
nr_moved = move_tasks(this_rq, this_cpu, busiest,
+ minus_1_or_zero(busiest->nr_running),
imbalance, sd, NEWLY_IDLE, NULL);
spin_unlock(&busiest->lock);
}
@@ -2361,7 +2508,8 @@ static void active_load_balance(runqueue_t *busiest_rq, int busiest_cpu)
schedstat_inc(sd, alb_cnt);
- if (move_tasks(target_rq, target_cpu, busiest_rq, 1, sd, SCHED_IDLE, NULL))
+ if (move_tasks(target_rq, target_cpu, busiest_rq, 1,
+ RTPRIO_TO_LOAD_WEIGHT(100), sd, SCHED_IDLE, NULL))
schedstat_inc(sd, alb_pushed);
else
schedstat_inc(sd, alb_failed);
@@ -2389,7 +2537,7 @@ static void rebalance_tick(int this_cpu, runqueue_t *this_rq,
struct sched_domain *sd;
int i;
- this_load = this_rq->nr_running * SCHED_LOAD_SCALE;
+ this_load = this_rq->raw_weighted_load;
/* Update our load */
for (i = 0; i < 3; i++) {
unsigned long new_load = this_load;
@@ -3441,17 +3589,21 @@ void set_user_nice(task_t *p, long nice)
goto out_unlock;
}
array = p->array;
- if (array)
+ if (array) {
dequeue_task(p, array);
+ dec_raw_weighted_load(rq, p);
+ }
old_prio = p->prio;
new_prio = NICE_TO_PRIO(nice);
delta = new_prio - old_prio;
p->static_prio = NICE_TO_PRIO(nice);
+ set_load_weight(p);
p->prio += delta;
if (array) {
enqueue_task(p, array);
+ inc_raw_weighted_load(rq, p);
/*
* If the task increased its priority or is running and
* lowered its priority, then reschedule its CPU:
@@ -3587,6 +3739,7 @@ static void __setscheduler(struct task_struct *p, int policy, int prio)
if (policy == SCHED_BATCH)
p->sleep_avg = 0;
}
+ set_load_weight(p);
}
/**
@@ -6106,6 +6259,7 @@ void __init sched_init(void)
}
}
+ set_load_weight(&init_task);
/*
* The boot idle thread does lazy MMU switching as well:
*/