summaryrefslogtreecommitdiff
path: root/kernel/sched/core.c
diff options
context:
space:
mode:
Diffstat (limited to 'kernel/sched/core.c')
-rw-r--r--kernel/sched/core.c249
1 files changed, 200 insertions, 49 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 39eb6011bc38..d5594a4268d4 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -142,9 +142,8 @@ const_debug unsigned int sysctl_sched_features =
#define SCHED_FEAT(name, enabled) \
#name ,
-static __read_mostly char *sched_feat_names[] = {
+static const char * const sched_feat_names[] = {
#include "features.h"
- NULL
};
#undef SCHED_FEAT
@@ -2517,25 +2516,32 @@ static void __update_cpu_load(struct rq *this_rq, unsigned long this_load,
sched_avg_update(this_rq);
}
+#ifdef CONFIG_NO_HZ
+/*
+ * There is no sane way to deal with nohz on smp when using jiffies because the
+ * cpu doing the jiffies update might drift wrt the cpu doing the jiffy reading
+ * causing off-by-one errors in observed deltas; {0,2} instead of {1,1}.
+ *
+ * Therefore we cannot use the delta approach from the regular tick since that
+ * would seriously skew the load calculation. However we'll make do for those
+ * updates happening while idle (nohz_idle_balance) or coming out of idle
+ * (tick_nohz_idle_exit).
+ *
+ * This means we might still be one tick off for nohz periods.
+ */
+
/*
* Called from nohz_idle_balance() to update the load ratings before doing the
* idle balance.
*/
void update_idle_cpu_load(struct rq *this_rq)
{
- unsigned long curr_jiffies = jiffies;
+ unsigned long curr_jiffies = ACCESS_ONCE(jiffies);
unsigned long load = this_rq->load.weight;
unsigned long pending_updates;
/*
- * Bloody broken means of dealing with nohz, but better than nothing..
- * jiffies is updated by one cpu, another cpu can drift wrt the jiffy
- * update and see 0 difference the one time and 2 the next, even though
- * we ticked at roughtly the same rate.
- *
- * Hence we only use this from nohz_idle_balance() and skip this
- * nonsense when called from the scheduler_tick() since that's
- * guaranteed a stable rate.
+ * bail if there's load or we're actually up-to-date.
*/
if (load || curr_jiffies == this_rq->last_load_update_tick)
return;
@@ -2547,12 +2553,38 @@ void update_idle_cpu_load(struct rq *this_rq)
}
/*
+ * Called from tick_nohz_idle_exit() -- try and fix up the ticks we missed.
+ */
+void update_cpu_load_nohz(void)
+{
+ struct rq *this_rq = this_rq();
+ unsigned long curr_jiffies = ACCESS_ONCE(jiffies);
+ unsigned long pending_updates;
+
+ if (curr_jiffies == this_rq->last_load_update_tick)
+ return;
+
+ raw_spin_lock(&this_rq->lock);
+ pending_updates = curr_jiffies - this_rq->last_load_update_tick;
+ if (pending_updates) {
+ this_rq->last_load_update_tick = curr_jiffies;
+ /*
+ * We were idle, this means load 0, the current load might be
+ * !0 due to remote wakeups and the sort.
+ */
+ __update_cpu_load(this_rq, 0, pending_updates);
+ }
+ raw_spin_unlock(&this_rq->lock);
+}
+#endif /* CONFIG_NO_HZ */
+
+/*
* Called from scheduler_tick()
*/
static void update_cpu_load_active(struct rq *this_rq)
{
/*
- * See the mess in update_idle_cpu_load().
+ * See the mess around update_idle_cpu_load() / update_cpu_load_nohz().
*/
this_rq->last_load_update_tick = jiffies;
__update_cpu_load(this_rq, this_rq->load.weight, 1);
@@ -4982,7 +5014,7 @@ void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
p->sched_class->set_cpus_allowed(p, new_mask);
cpumask_copy(&p->cpus_allowed, new_mask);
- p->rt.nr_cpus_allowed = cpumask_weight(new_mask);
+ p->nr_cpus_allowed = cpumask_weight(new_mask);
}
/*
@@ -5524,15 +5556,20 @@ static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */
#ifdef CONFIG_SCHED_DEBUG
-static __read_mostly int sched_domain_debug_enabled;
+static __read_mostly int sched_debug_enabled;
-static int __init sched_domain_debug_setup(char *str)
+static int __init sched_debug_setup(char *str)
{
- sched_domain_debug_enabled = 1;
+ sched_debug_enabled = 1;
return 0;
}
-early_param("sched_debug", sched_domain_debug_setup);
+early_param("sched_debug", sched_debug_setup);
+
+static inline bool sched_debug(void)
+{
+ return sched_debug_enabled;
+}
static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
struct cpumask *groupmask)
@@ -5572,7 +5609,12 @@ static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
break;
}
- if (!group->sgp->power) {
+ /*
+ * Even though we initialize ->power to something semi-sane,
+ * we leave power_orig unset. This allows us to detect if
+ * domain iteration is still funny without causing /0 traps.
+ */
+ if (!group->sgp->power_orig) {
printk(KERN_CONT "\n");
printk(KERN_ERR "ERROR: domain->cpu_power not "
"set\n");
@@ -5620,7 +5662,7 @@ static void sched_domain_debug(struct sched_domain *sd, int cpu)
{
int level = 0;
- if (!sched_domain_debug_enabled)
+ if (!sched_debug_enabled)
return;
if (!sd) {
@@ -5641,6 +5683,10 @@ static void sched_domain_debug(struct sched_domain *sd, int cpu)
}
#else /* !CONFIG_SCHED_DEBUG */
# define sched_domain_debug(sd, cpu) do { } while (0)
+static inline bool sched_debug(void)
+{
+ return false;
+}
#endif /* CONFIG_SCHED_DEBUG */
static int sd_degenerate(struct sched_domain *sd)
@@ -5962,6 +6008,44 @@ struct sched_domain_topology_level {
struct sd_data data;
};
+/*
+ * Build an iteration mask that can exclude certain CPUs from the upwards
+ * domain traversal.
+ *
+ * Asymmetric node setups can result in situations where the domain tree is of
+ * unequal depth, make sure to skip domains that already cover the entire
+ * range.
+ *
+ * In that case build_sched_domains() will have terminated the iteration early
+ * and our sibling sd spans will be empty. Domains should always include the
+ * cpu they're built on, so check that.
+ *
+ */
+static void build_group_mask(struct sched_domain *sd, struct sched_group *sg)
+{
+ const struct cpumask *span = sched_domain_span(sd);
+ struct sd_data *sdd = sd->private;
+ struct sched_domain *sibling;
+ int i;
+
+ for_each_cpu(i, span) {
+ sibling = *per_cpu_ptr(sdd->sd, i);
+ if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
+ continue;
+
+ cpumask_set_cpu(i, sched_group_mask(sg));
+ }
+}
+
+/*
+ * Return the canonical balance cpu for this group, this is the first cpu
+ * of this group that's also in the iteration mask.
+ */
+int group_balance_cpu(struct sched_group *sg)
+{
+ return cpumask_first_and(sched_group_cpus(sg), sched_group_mask(sg));
+}
+
static int
build_overlap_sched_groups(struct sched_domain *sd, int cpu)
{
@@ -5980,6 +6064,12 @@ build_overlap_sched_groups(struct sched_domain *sd, int cpu)
if (cpumask_test_cpu(i, covered))
continue;
+ child = *per_cpu_ptr(sdd->sd, i);
+
+ /* See the comment near build_group_mask(). */
+ if (!cpumask_test_cpu(i, sched_domain_span(child)))
+ continue;
+
sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
GFP_KERNEL, cpu_to_node(cpu));
@@ -5987,8 +6077,6 @@ build_overlap_sched_groups(struct sched_domain *sd, int cpu)
goto fail;
sg_span = sched_group_cpus(sg);
-
- child = *per_cpu_ptr(sdd->sd, i);
if (child->child) {
child = child->child;
cpumask_copy(sg_span, sched_domain_span(child));
@@ -5997,10 +6085,24 @@ build_overlap_sched_groups(struct sched_domain *sd, int cpu)
cpumask_or(covered, covered, sg_span);
- sg->sgp = *per_cpu_ptr(sdd->sgp, cpumask_first(sg_span));
- atomic_inc(&sg->sgp->ref);
+ sg->sgp = *per_cpu_ptr(sdd->sgp, i);
+ if (atomic_inc_return(&sg->sgp->ref) == 1)
+ build_group_mask(sd, sg);
- if (cpumask_test_cpu(cpu, sg_span))
+ /*
+ * Initialize sgp->power such that even if we mess up the
+ * domains and no possible iteration will get us here, we won't
+ * die on a /0 trap.
+ */
+ sg->sgp->power = SCHED_POWER_SCALE * cpumask_weight(sg_span);
+
+ /*
+ * Make sure the first group of this domain contains the
+ * canonical balance cpu. Otherwise the sched_domain iteration
+ * breaks. See update_sg_lb_stats().
+ */
+ if ((!groups && cpumask_test_cpu(cpu, sg_span)) ||
+ group_balance_cpu(sg) == cpu)
groups = sg;
if (!first)
@@ -6074,6 +6176,7 @@ build_sched_groups(struct sched_domain *sd, int cpu)
cpumask_clear(sched_group_cpus(sg));
sg->sgp->power = 0;
+ cpumask_setall(sched_group_mask(sg));
for_each_cpu(j, span) {
if (get_group(j, sdd, NULL) != group)
@@ -6115,7 +6218,7 @@ static void init_sched_groups_power(int cpu, struct sched_domain *sd)
sg = sg->next;
} while (sg != sd->groups);
- if (cpu != group_first_cpu(sg))
+ if (cpu != group_balance_cpu(sg))
return;
update_group_power(sd, cpu);
@@ -6165,11 +6268,8 @@ int sched_domain_level_max;
static int __init setup_relax_domain_level(char *str)
{
- unsigned long val;
-
- val = simple_strtoul(str, NULL, 0);
- if (val < sched_domain_level_max)
- default_relax_domain_level = val;
+ if (kstrtoint(str, 0, &default_relax_domain_level))
+ pr_warn("Unable to set relax_domain_level\n");
return 1;
}
@@ -6279,14 +6379,13 @@ static struct sched_domain_topology_level *sched_domain_topology = default_topol
#ifdef CONFIG_NUMA
static int sched_domains_numa_levels;
-static int sched_domains_numa_scale;
static int *sched_domains_numa_distance;
static struct cpumask ***sched_domains_numa_masks;
static int sched_domains_curr_level;
static inline int sd_local_flags(int level)
{
- if (sched_domains_numa_distance[level] > REMOTE_DISTANCE)
+ if (sched_domains_numa_distance[level] > RECLAIM_DISTANCE)
return 0;
return SD_BALANCE_EXEC | SD_BALANCE_FORK | SD_WAKE_AFFINE;
@@ -6344,6 +6443,42 @@ static const struct cpumask *sd_numa_mask(int cpu)
return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)];
}
+static void sched_numa_warn(const char *str)
+{
+ static int done = false;
+ int i,j;
+
+ if (done)
+ return;
+
+ done = true;
+
+ printk(KERN_WARNING "ERROR: %s\n\n", str);
+
+ for (i = 0; i < nr_node_ids; i++) {
+ printk(KERN_WARNING " ");
+ for (j = 0; j < nr_node_ids; j++)
+ printk(KERN_CONT "%02d ", node_distance(i,j));
+ printk(KERN_CONT "\n");
+ }
+ printk(KERN_WARNING "\n");
+}
+
+static bool find_numa_distance(int distance)
+{
+ int i;
+
+ if (distance == node_distance(0, 0))
+ return true;
+
+ for (i = 0; i < sched_domains_numa_levels; i++) {
+ if (sched_domains_numa_distance[i] == distance)
+ return true;
+ }
+
+ return false;
+}
+
static void sched_init_numa(void)
{
int next_distance, curr_distance = node_distance(0, 0);
@@ -6351,7 +6486,6 @@ static void sched_init_numa(void)
int level = 0;
int i, j, k;
- sched_domains_numa_scale = curr_distance;
sched_domains_numa_distance = kzalloc(sizeof(int) * nr_node_ids, GFP_KERNEL);
if (!sched_domains_numa_distance)
return;
@@ -6362,23 +6496,41 @@ static void sched_init_numa(void)
*
* Assumes node_distance(0,j) includes all distances in
* node_distance(i,j) in order to avoid cubic time.
- *
- * XXX: could be optimized to O(n log n) by using sort()
*/
next_distance = curr_distance;
for (i = 0; i < nr_node_ids; i++) {
for (j = 0; j < nr_node_ids; j++) {
- int distance = node_distance(0, j);
- if (distance > curr_distance &&
- (distance < next_distance ||
- next_distance == curr_distance))
- next_distance = distance;
+ for (k = 0; k < nr_node_ids; k++) {
+ int distance = node_distance(i, k);
+
+ if (distance > curr_distance &&
+ (distance < next_distance ||
+ next_distance == curr_distance))
+ next_distance = distance;
+
+ /*
+ * While not a strong assumption it would be nice to know
+ * about cases where if node A is connected to B, B is not
+ * equally connected to A.
+ */
+ if (sched_debug() && node_distance(k, i) != distance)
+ sched_numa_warn("Node-distance not symmetric");
+
+ if (sched_debug() && i && !find_numa_distance(distance))
+ sched_numa_warn("Node-0 not representative");
+ }
+ if (next_distance != curr_distance) {
+ sched_domains_numa_distance[level++] = next_distance;
+ sched_domains_numa_levels = level;
+ curr_distance = next_distance;
+ } else break;
}
- if (next_distance != curr_distance) {
- sched_domains_numa_distance[level++] = next_distance;
- sched_domains_numa_levels = level;
- curr_distance = next_distance;
- } else break;
+
+ /*
+ * In case of sched_debug() we verify the above assumption.
+ */
+ if (!sched_debug())
+ break;
}
/*
* 'level' contains the number of unique distances, excluding the
@@ -6403,7 +6555,7 @@ static void sched_init_numa(void)
return;
for (j = 0; j < nr_node_ids; j++) {
- struct cpumask *mask = kzalloc_node(cpumask_size(), GFP_KERNEL, j);
+ struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL);
if (!mask)
return;
@@ -6490,7 +6642,7 @@ static int __sdt_alloc(const struct cpumask *cpu_map)
*per_cpu_ptr(sdd->sg, j) = sg;
- sgp = kzalloc_node(sizeof(struct sched_group_power),
+ sgp = kzalloc_node(sizeof(struct sched_group_power) + cpumask_size(),
GFP_KERNEL, cpu_to_node(j));
if (!sgp)
return -ENOMEM;
@@ -6543,7 +6695,6 @@ struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl,
if (!sd)
return child;
- set_domain_attribute(sd, attr);
cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu));
if (child) {
sd->level = child->level + 1;
@@ -6551,6 +6702,7 @@ struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl,
child->parent = sd;
}
sd->child = child;
+ set_domain_attribute(sd, attr);
return sd;
}
@@ -6691,7 +6843,6 @@ static int init_sched_domains(const struct cpumask *cpu_map)
if (!doms_cur)
doms_cur = &fallback_doms;
cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map);
- dattr_cur = NULL;
err = build_sched_domains(doms_cur[0], NULL);
register_sched_domain_sysctl();