[GIT PULL] scheduler fixes

Ingo Molnar
2011-07-20T21:07:35Z

Linus,

Please pull the latest sched-urgent-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git sched-urgent-for-linus

Thanks,

Ingo

------------------>
Peter Zijlstra (3):
sched: Break out cpu_power from the sched_group structure
sched: Allow for overlapping sched_domain spans
sched: Avoid creating superfluous NUMA domains on non-NUMA systems

include/linux/sched.h | 14 +++-
kernel/sched.c | 189 ++++++++++++++++++++++++++++++++++++++---------
kernel/sched_fair.c | 46 ++++++------
kernel/sched_features.h | 2 +
4 files changed, 190 insertions(+), 61 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 496770a..bde99d5 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -844,6 +844,7 @@ enum cpu_idle_type {
#define SD_SERIALIZE 0x0400 /* Only a single load balancing instance */
#define SD_ASYM_PACKING 0x0800 /* Place busy groups earlier in the domain */
#define SD_PREFER_SIBLING 0x1000 /* Prefer to place tasks in a sibling domain */
+#define SD_OVERLAP 0x2000 /* sched_domains of this level overlap */

enum powersavings_balance_level {
POWERSAVINGS_BALANCE_NONE = 0, /* No power saving load balance */
@@ -893,16 +894,21 @@ static inline int sd_power_saving_flags(void)
return 0;
}

-struct sched_group {
- struct sched_group *next; /* Must be a circular list */
+struct sched_group_power {
atomic_t ref;
-
/*
* CPU power of this group, SCHED_LOAD_SCALE being max power for a
* single CPU.
*/
- unsigned int cpu_power, cpu_power_orig;
+ unsigned int power, power_orig;
+};
+
+struct sched_group {
+ struct sched_group *next; /* Must be a circular list */
+ atomic_t ref;
+
unsigned int group_weight;
+ struct sched_group_power *sgp;

/*
* The CPUs this group covers.
diff --git a/kernel/sched.c b/kernel/sched.c
index 3dc716f..14168c4 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6557,7 +6557,7 @@ static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
break;
}

- if (!group->cpu_power) {
+ if (!group->sgp->power) {
printk(KERN_CONT "\n");
printk(KERN_ERR "ERROR: domain->cpu_power not "
"set\n");
@@ -6581,9 +6581,9 @@ static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
cpulist_scnprintf(str, sizeof(str), sched_group_cpus(group));

printk(KERN_CONT " %s", str);
- if (group->cpu_power != SCHED_POWER_SCALE) {
+ if (group->sgp->power != SCHED_POWER_SCALE) {
printk(KERN_CONT " (cpu_power = %d)",
- group->cpu_power);
+ group->sgp->power);
}

group = group->next;
@@ -6774,11 +6774,39 @@ static struct root_domain *alloc_rootdomain(void)
return rd;
}

+static void free_sched_groups(struct sched_group *sg, int free_sgp)
+{
+ struct sched_group *tmp, *first;
+
+ if (!sg)
+ return;
+
+ first = sg;
+ do {
+ tmp = sg->next;
+
+ if (free_sgp && atomic_dec_and_test(&sg->sgp->ref))
+ kfree(sg->sgp);
+
+ kfree(sg);
+ sg = tmp;
+ } while (sg != first);
+}
+
static void free_sched_domain(struct rcu_head *rcu)
{
struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
- if (atomic_dec_and_test(&sd->groups->ref))
+
+ /*
+ * If its an overlapping domain it has private groups, iterate and
+ * nuke them all.
+ */
+ if (sd->flags & SD_OVERLAP) {
+ free_sched_groups(sd->groups, 1);
+ } else if (atomic_dec_and_test(&sd->groups->ref)) {
+ kfree(sd->groups->sgp);
kfree(sd->groups);
+ }
kfree(sd);
}

@@ -6945,6 +6973,7 @@ int sched_smt_power_savings = 0, sched_mc_power_savings = 0;
struct sd_data {
struct sched_domain **__percpu sd;
struct sched_group **__percpu sg;
+ struct sched_group_power **__percpu sgp;
};

struct s_data {
@@ -6964,15 +6993,73 @@ struct sched_domain_topology_level;
typedef struct sched_domain *(*sched_domain_init_f)(struct sched_domain_topology_level *tl, int cpu);
typedef const struct cpumask *(*sched_domain_mask_f)(int cpu);

+#define SDTL_OVERLAP 0x01
+
struct sched_domain_topology_level {
sched_domain_init_f init;
sched_domain_mask_f mask;
+ int flags;
struct sd_data data;
};

-/*
- * Assumes the sched_domain tree is fully constructed
- */
+static int
+build_overlap_sched_groups(struct sched_domain *sd, int cpu)
+{
+ struct sched_group *first = NULL, *last = NULL, *groups = NULL, *sg;
+ const struct cpumask *span = sched_domain_span(sd);
+ struct cpumask *covered = sched_domains_tmpmask;
+ struct sd_data *sdd = sd->private;
+ struct sched_domain *child;
+ int i;
+
+ cpumask_clear(covered);
+
+ for_each_cpu(i, span) {
+ struct cpumask *sg_span;
+
+ if (cpumask_test_cpu(i, covered))
+ continue;
+
+ sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
+ GFP_KERNEL, cpu_to_node(i));
+
+ if (!sg)
+ 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));
+ } else
+ cpumask_set_cpu(i, sg_span);
+
+ cpumask_or(covered, covered, sg_span);
+
+ sg->sgp = *per_cpu_ptr(sdd->sgp, cpumask_first(sg_span));
+ atomic_inc(&sg->sgp->ref);
+
+ if (cpumask_test_cpu(cpu, sg_span))
+ groups = sg;
+
+ if (!first)
+ first = sg;
+ if (last)
+ last->next = sg;
+ last = sg;
+ last->next = first;
+ }
+ sd->groups = groups;
+
+ return 0;
+
+fail:
+ free_sched_groups(first, 0);
+
+ return -ENOMEM;
+}
+
static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg)
{
struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
@@ -6981,24 +7068,24 @@ static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg)
if (child)
cpu = cpumask_first(sched_domain_span(child));

- if (sg)
+ if (sg) {
*sg = *per_cpu_ptr(sdd->sg, cpu);
+ (*sg)->sgp = *per_cpu_ptr(sdd->sgp, cpu);
+ atomic_set(&(*sg)->sgp->ref, 1); /* for claim_allocations */
+ }

return cpu;
}

/*
- * build_sched_groups takes the cpumask we wish to span, and a pointer
- * to a function which identifies what group(along with sched group) a CPU
- * belongs to. The return value of group_fn must be a >= 0 and < nr_cpu_ids
- * (due to the fact that we keep track of groups covered with a struct cpumask).
- *
* build_sched_groups will build a circular linked list of the groups
* covered by the given span, and will set each group's ->cpumask correctly,
* and ->cpu_power to 0.
+ *
+ * Assumes the sched_domain tree is fully constructed
*/
-static void
-build_sched_groups(struct sched_domain *sd)
+static int
+build_sched_groups(struct sched_domain *sd, int cpu)
{
struct sched_group *first = NULL, *last = NULL;
struct sd_data *sdd = sd->private;
@@ -7006,6 +7093,12 @@ build_sched_groups(struct sched_domain *sd)
struct cpumask *covered;
int i;

+ get_group(cpu, sdd, &sd->groups);
+ atomic_inc(&sd->groups->ref);
+
+ if (cpu != cpumask_first(sched_domain_span(sd)))
+ return 0;
+
lockdep_assert_held(&sched_domains_mutex);
covered = sched_domains_tmpmask;

@@ -7020,7 +7113,7 @@ build_sched_groups(struct sched_domain *sd)
continue;

cpumask_clear(sched_group_cpus(sg));
- sg->cpu_power = 0;
+ sg->sgp->power = 0;

for_each_cpu(j, span) {
if (get_group(j, sdd, NULL) != group)
@@ -7037,6 +7130,8 @@ build_sched_groups(struct sched_domain *sd)
last = sg;
}
last->next = first;
+
+ return 0;
}

/*
@@ -7051,12 +7146,17 @@ build_sched_groups(struct sched_domain *sd)
*/
static void init_sched_groups_power(int cpu, struct sched_domain *sd)
{
- WARN_ON(!sd || !sd->groups);
+ struct sched_group *sg = sd->groups;

- if (cpu != group_first_cpu(sd->groups))
- return;
+ WARN_ON(!sd || !sg);

- sd->groups->group_weight = cpumask_weight(sched_group_cpus(sd->groups));
+ do {
+ sg->group_weight = cpumask_weight(sched_group_cpus(sg));
+ sg = sg->next;
+ } while (sg != sd->groups);
+
+ if (cpu != group_first_cpu(sg))
+ return;

update_group_power(sd, cpu);
}
@@ -7177,15 +7277,15 @@ static enum s_alloc __visit_domain_allocation_hell(struct s_data *d,
static void claim_allocations(int cpu, struct sched_domain *sd)
{
struct sd_data *sdd = sd->private;
- struct sched_group *sg = sd->groups;

WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd);
*per_cpu_ptr(sdd->sd, cpu) = NULL;

- if (cpu == cpumask_first(sched_group_cpus(sg))) {
- WARN_ON_ONCE(*per_cpu_ptr(sdd->sg, cpu) != sg);
+ if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref))
*per_cpu_ptr(sdd->sg, cpu) = NULL;
- }
+
+ if (atomic_read(&(*per_cpu_ptr(sdd->sgp, cpu))->ref))
+ *per_cpu_ptr(sdd->sgp, cpu) = NULL;
}

#ifdef CONFIG_SCHED_SMT
@@ -7210,7 +7310,7 @@ static struct sched_domain_topology_level default_topology[] = {
#endif
{ sd_init_CPU, cpu_cpu_mask, },
#ifdef CONFIG_NUMA
- { sd_init_NODE, cpu_node_mask, },
+ { sd_init_NODE, cpu_node_mask, SDTL_OVERLAP, },
{ sd_init_ALLNODES, cpu_allnodes_mask, },
#endif
{ NULL, },
@@ -7234,9 +7334,14 @@ static int __sdt_alloc(const struct cpumask *cpu_map)
if (!sdd->sg)
return -ENOMEM;

+ sdd->sgp = alloc_percpu(struct sched_group_power *);
+ if (!sdd->sgp)
+ return -ENOMEM;
+
for_each_cpu(j, cpu_map) {
struct sched_domain *sd;
struct sched_group *sg;
+ struct sched_group_power *sgp;

sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(),
GFP_KERNEL, cpu_to_node(j));
@@ -7251,6 +7356,13 @@ static int __sdt_alloc(const struct cpumask *cpu_map)
return -ENOMEM;

*per_cpu_ptr(sdd->sg, j) = sg;
+
+ sgp = kzalloc_node(sizeof(struct sched_group_power),
+ GFP_KERNEL, cpu_to_node(j));
+ if (!sgp)
+ return -ENOMEM;
+
+ *per_cpu_ptr(sdd->sgp, j) = sgp;
}
}

@@ -7266,11 +7378,15 @@ static void __sdt_free(const struct cpumask *cpu_map)
struct sd_data *sdd = &tl->data;

for_each_cpu(j, cpu_map) {
- kfree(*per_cpu_ptr(sdd->sd, j));
+ struct sched_domain *sd = *per_cpu_ptr(sdd->sd, j);
+ if (sd && (sd->flags & SD_OVERLAP))
+ free_sched_groups(sd->groups, 0);
kfree(*per_cpu_ptr(sdd->sg, j));
+ kfree(*per_cpu_ptr(sdd->sgp, j));
}
free_percpu(sdd->sd);
free_percpu(sdd->sg);
+ free_percpu(sdd->sgp);
}
}

@@ -7316,8 +7432,13 @@ static int build_sched_domains(const struct cpumask *cpu_map,
struct sched_domain_topology_level *tl;

sd = NULL;
- for (tl = sched_domain_topology; tl->init; tl++)
+ for (tl = sched_domain_topology; tl->init; tl++) {
sd = build_sched_domain(tl, &d, cpu_map, attr, sd, i);
+ if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP))
+ sd->flags |= SD_OVERLAP;
+ if (cpumask_equal(cpu_map, sched_domain_span(sd)))
+ break;
+ }

while (sd->child)
sd = sd->child;
@@ -7329,13 +7450,13 @@ static int build_sched_domains(const struct cpumask *cpu_map,
for_each_cpu(i, cpu_map) {
for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
sd->span_weight = cpumask_weight(sched_domain_span(sd));
- get_group(i, sd->private, &sd->groups);
- atomic_inc(&sd->groups->ref);
-
- if (i != cpumask_first(sched_domain_span(sd)))
- continue;
-
- build_sched_groups(sd);
+ if (sd->flags & SD_OVERLAP) {
+ if (build_overlap_sched_groups(sd, i))
+ goto error;
+ } else {
+ if (build_sched_groups(sd, i))
+ goto error;
+ }
}
}

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 433491c..c768588 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1585,7 +1585,7 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p,
}

/* Adjust by relative CPU power of the group */
- avg_load = (avg_load * SCHED_POWER_SCALE) / group->cpu_power;
+ avg_load = (avg_load * SCHED_POWER_SCALE) / group->sgp->power;

if (local_group) {
this_load = avg_load;
@@ -2631,7 +2631,7 @@ static void update_cpu_power(struct sched_domain *sd, int cpu)
power >>= SCHED_POWER_SHIFT;
}

- sdg->cpu_power_orig = power;
+ sdg->sgp->power_orig = power;

if (sched_feat(ARCH_POWER))
power *= arch_scale_freq_power(sd, cpu);
@@ -2647,7 +2647,7 @@ static void update_cpu_power(struct sched_domain *sd, int cpu)
power = 1;

cpu_rq(cpu)->cpu_power = power;
- sdg->cpu_power = power;
+ sdg->sgp->power = power;
}

static void update_group_power(struct sched_domain *sd, int cpu)
@@ -2665,11 +2665,11 @@ static void update_group_power(struct sched_domain *sd, int cpu)

group = child->groups;
do {
- power += group->cpu_power;
+ power += group->sgp->power;
group = group->next;
} while (group != child->groups);

- sdg->cpu_power = power;
+ sdg->sgp->power = power;
}

/*
@@ -2691,7 +2691,7 @@ fix_small_capacity(struct sched_domain *sd, struct sched_group *group)
/*
* If ~90% of the cpu_power is still there, we're good.
*/
- if (group->cpu_power * 32 > group->cpu_power_orig * 29)
+ if (group->sgp->power * 32 > group->sgp->power_orig * 29)
return 1;

return 0;
@@ -2771,7 +2771,7 @@ static inline void update_sg_lb_stats(struct sched_domain *sd,
}

/* Adjust by relative CPU power of the group */
- sgs->avg_load = (sgs->group_load*SCHED_POWER_SCALE) / group->cpu_power;
+ sgs->avg_load = (sgs->group_load*SCHED_POWER_SCALE) / group->sgp->power;

/*
* Consider the group unbalanced when the imbalance is larger
@@ -2788,7 +2788,7 @@ static inline void update_sg_lb_stats(struct sched_domain *sd,
if ((max_cpu_load - min_cpu_load) >= avg_load_per_task && max_nr_running > 1)
sgs->group_imb = 1;

- sgs->group_capacity = DIV_ROUND_CLOSEST(group->cpu_power,
+ sgs->group_capacity = DIV_ROUND_CLOSEST(group->sgp->power,
SCHED_POWER_SCALE);
if (!sgs->group_capacity)
sgs->group_capacity = fix_small_capacity(sd, group);
@@ -2877,7 +2877,7 @@ static inline void update_sd_lb_stats(struct sched_domain *sd, int this_cpu,
return;

sds->total_load += sgs.group_load;
- sds->total_pwr += sg->cpu_power;
+ sds->total_pwr += sg->sgp->power;

/*
* In case the child domain prefers tasks go to siblings
@@ -2962,7 +2962,7 @@ static int check_asym_packing(struct sched_domain *sd,
if (this_cpu > busiest_cpu)
return 0;

- *imbalance = DIV_ROUND_CLOSEST(sds->max_load * sds->busiest->cpu_power,
+ *imbalance = DIV_ROUND_CLOSEST(sds->max_load * sds->busiest->sgp->power,
SCHED_POWER_SCALE);
return 1;
}
@@ -2993,7 +2993,7 @@ static inline void fix_small_imbalance(struct sd_lb_stats *sds,

scaled_busy_load_per_task = sds->busiest_load_per_task
* SCHED_POWER_SCALE;
- scaled_busy_load_per_task /= sds->busiest->cpu_power;
+ scaled_busy_load_per_task /= sds->busiest->sgp->power;

if (sds->max_load - sds->this_load + scaled_busy_load_per_task >=
(scaled_busy_load_per_task * imbn)) {
@@ -3007,28 +3007,28 @@ static inline void fix_small_imbalance(struct sd_lb_stats *sds,
* moving them.
*/

- pwr_now += sds->busiest->cpu_power *
+ pwr_now += sds->busiest->sgp->power *
min(sds->busiest_load_per_task, sds->max_load);
- pwr_now += sds->this->cpu_power *
+ pwr_now += sds->this->sgp->power *
min(sds->this_load_per_task, sds->this_load);
pwr_now /= SCHED_POWER_SCALE;

/* Amount of load we'd subtract */
tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) /
- sds->busiest->cpu_power;
+ sds->busiest->sgp->power;
if (sds->max_load > tmp)
- pwr_move += sds->busiest->cpu_power *
+ pwr_move += sds->busiest->sgp->power *
min(sds->busiest_load_per_task, sds->max_load - tmp);

/* Amount of load we'd add */
- if (sds->max_load * sds->busiest->cpu_power <
+ if (sds->max_load * sds->busiest->sgp->power <
sds->busiest_load_per_task * SCHED_POWER_SCALE)
- tmp = (sds->max_load * sds->busiest->cpu_power) /
- sds->this->cpu_power;
+ tmp = (sds->max_load * sds->busiest->sgp->power) /
+ sds->this->sgp->power;
else
tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) /
- sds->this->cpu_power;
- pwr_move += sds->this->cpu_power *
+ sds->this->sgp->power;
+ pwr_move += sds->this->sgp->power *
min(sds->this_load_per_task, sds->this_load + tmp);
pwr_move /= SCHED_POWER_SCALE;

@@ -3074,7 +3074,7 @@ static inline void calculate_imbalance(struct sd_lb_stats *sds, int this_cpu,

load_above_capacity *= (SCHED_LOAD_SCALE * SCHED_POWER_SCALE);

- load_above_capacity /= sds->busiest->cpu_power;
+ load_above_capacity /= sds->busiest->sgp->power;
}

/*
@@ -3090,8 +3090,8 @@ static inline void calculate_imbalance(struct sd_lb_stats *sds, int this_cpu,
max_pull = min(sds->max_load - sds->avg_load, load_above_capacity);

/* How much load to actually move to equalise the imbalance */
- *imbalance = min(max_pull * sds->busiest->cpu_power,
- (sds->avg_load - sds->this_load) * sds->this->cpu_power)
+ *imbalance = min(max_pull * sds->busiest->sgp->power,
+ (sds->avg_load - sds->this_load) * sds->this->sgp->power)
/ SCHED_POWER_SCALE;

/*
diff --git a/kernel/sched_features.h b/kernel/sched_features.h
index be40f73..1e7066d 100644
--- a/kernel/sched_features.h
+++ b/kernel/sched_features.h
@@ -70,3 +70,5 @@ SCHED_FEAT(NONIRQ_POWER, 1)
* using the scheduler IPI. Reduces rq->lock contention/bounces.
*/
SCHED_FEAT(TTWU_QUEUE, 1)
+
+SCHED_FEAT(FORCE_SD_OVERLAP, 0)