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-rw-r--r--kernel/sched/fair.c354
1 files changed, 268 insertions, 86 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index ef2b104b254c..df2cdf77f899 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -873,7 +873,6 @@ struct numa_group {
spinlock_t lock; /* nr_tasks, tasks */
int nr_tasks;
pid_t gid;
- struct list_head task_list;
struct rcu_head rcu;
nodemask_t active_nodes;
@@ -901,18 +900,24 @@ pid_t task_numa_group_id(struct task_struct *p)
return p->numa_group ? p->numa_group->gid : 0;
}
-static inline int task_faults_idx(int nid, int priv)
+/*
+ * The averaged statistics, shared & private, memory & cpu,
+ * occupy the first half of the array. The second half of the
+ * array is for current counters, which are averaged into the
+ * first set by task_numa_placement.
+ */
+static inline int task_faults_idx(enum numa_faults_stats s, int nid, int priv)
{
- return NR_NUMA_HINT_FAULT_TYPES * nid + priv;
+ return NR_NUMA_HINT_FAULT_TYPES * (s * nr_node_ids + nid) + priv;
}
static inline unsigned long task_faults(struct task_struct *p, int nid)
{
- if (!p->numa_faults_memory)
+ if (!p->numa_faults)
return 0;
- return p->numa_faults_memory[task_faults_idx(nid, 0)] +
- p->numa_faults_memory[task_faults_idx(nid, 1)];
+ return p->numa_faults[task_faults_idx(NUMA_MEM, nid, 0)] +
+ p->numa_faults[task_faults_idx(NUMA_MEM, nid, 1)];
}
static inline unsigned long group_faults(struct task_struct *p, int nid)
@@ -920,14 +925,79 @@ static inline unsigned long group_faults(struct task_struct *p, int nid)
if (!p->numa_group)
return 0;
- return p->numa_group->faults[task_faults_idx(nid, 0)] +
- p->numa_group->faults[task_faults_idx(nid, 1)];
+ return p->numa_group->faults[task_faults_idx(NUMA_MEM, nid, 0)] +
+ p->numa_group->faults[task_faults_idx(NUMA_MEM, nid, 1)];
}
static inline unsigned long group_faults_cpu(struct numa_group *group, int nid)
{
- return group->faults_cpu[task_faults_idx(nid, 0)] +
- group->faults_cpu[task_faults_idx(nid, 1)];
+ return group->faults_cpu[task_faults_idx(NUMA_MEM, nid, 0)] +
+ group->faults_cpu[task_faults_idx(NUMA_MEM, nid, 1)];
+}
+
+/* Handle placement on systems where not all nodes are directly connected. */
+static unsigned long score_nearby_nodes(struct task_struct *p, int nid,
+ int maxdist, bool task)
+{
+ unsigned long score = 0;
+ int node;
+
+ /*
+ * All nodes are directly connected, and the same distance
+ * from each other. No need for fancy placement algorithms.
+ */
+ if (sched_numa_topology_type == NUMA_DIRECT)
+ return 0;
+
+ /*
+ * This code is called for each node, introducing N^2 complexity,
+ * which should be ok given the number of nodes rarely exceeds 8.
+ */
+ for_each_online_node(node) {
+ unsigned long faults;
+ int dist = node_distance(nid, node);
+
+ /*
+ * The furthest away nodes in the system are not interesting
+ * for placement; nid was already counted.
+ */
+ if (dist == sched_max_numa_distance || node == nid)
+ continue;
+
+ /*
+ * On systems with a backplane NUMA topology, compare groups
+ * of nodes, and move tasks towards the group with the most
+ * memory accesses. When comparing two nodes at distance
+ * "hoplimit", only nodes closer by than "hoplimit" are part
+ * of each group. Skip other nodes.
+ */
+ if (sched_numa_topology_type == NUMA_BACKPLANE &&
+ dist > maxdist)
+ continue;
+
+ /* Add up the faults from nearby nodes. */
+ if (task)
+ faults = task_faults(p, node);
+ else
+ faults = group_faults(p, node);
+
+ /*
+ * On systems with a glueless mesh NUMA topology, there are
+ * no fixed "groups of nodes". Instead, nodes that are not
+ * directly connected bounce traffic through intermediate
+ * nodes; a numa_group can occupy any set of nodes.
+ * The further away a node is, the less the faults count.
+ * This seems to result in good task placement.
+ */
+ if (sched_numa_topology_type == NUMA_GLUELESS_MESH) {
+ faults *= (sched_max_numa_distance - dist);
+ faults /= (sched_max_numa_distance - LOCAL_DISTANCE);
+ }
+
+ score += faults;
+ }
+
+ return score;
}
/*
@@ -936,11 +1006,12 @@ static inline unsigned long group_faults_cpu(struct numa_group *group, int nid)
* larger multiplier, in order to group tasks together that are almost
* evenly spread out between numa nodes.
*/
-static inline unsigned long task_weight(struct task_struct *p, int nid)
+static inline unsigned long task_weight(struct task_struct *p, int nid,
+ int dist)
{
- unsigned long total_faults;
+ unsigned long faults, total_faults;
- if (!p->numa_faults_memory)
+ if (!p->numa_faults)
return 0;
total_faults = p->total_numa_faults;
@@ -948,15 +1019,29 @@ static inline unsigned long task_weight(struct task_struct *p, int nid)
if (!total_faults)
return 0;
- return 1000 * task_faults(p, nid) / total_faults;
+ faults = task_faults(p, nid);
+ faults += score_nearby_nodes(p, nid, dist, true);
+
+ return 1000 * faults / total_faults;
}
-static inline unsigned long group_weight(struct task_struct *p, int nid)
+static inline unsigned long group_weight(struct task_struct *p, int nid,
+ int dist)
{
- if (!p->numa_group || !p->numa_group->total_faults)
+ unsigned long faults, total_faults;
+
+ if (!p->numa_group)
return 0;
- return 1000 * group_faults(p, nid) / p->numa_group->total_faults;
+ total_faults = p->numa_group->total_faults;
+
+ if (!total_faults)
+ return 0;
+
+ faults = group_faults(p, nid);
+ faults += score_nearby_nodes(p, nid, dist, false);
+
+ return 1000 * faults / total_faults;
}
bool should_numa_migrate_memory(struct task_struct *p, struct page * page,
@@ -1089,6 +1174,7 @@ struct task_numa_env {
struct numa_stats src_stats, dst_stats;
int imbalance_pct;
+ int dist;
struct task_struct *best_task;
long best_imp;
@@ -1168,6 +1254,7 @@ static void task_numa_compare(struct task_numa_env *env,
long load;
long imp = env->p->numa_group ? groupimp : taskimp;
long moveimp = imp;
+ int dist = env->dist;
rcu_read_lock();
@@ -1208,8 +1295,8 @@ static void task_numa_compare(struct task_numa_env *env,
* in any group then look only at task weights.
*/
if (cur->numa_group == env->p->numa_group) {
- imp = taskimp + task_weight(cur, env->src_nid) -
- task_weight(cur, env->dst_nid);
+ imp = taskimp + task_weight(cur, env->src_nid, dist) -
+ task_weight(cur, env->dst_nid, dist);
/*
* Add some hysteresis to prevent swapping the
* tasks within a group over tiny differences.
@@ -1223,11 +1310,11 @@ static void task_numa_compare(struct task_numa_env *env,
* instead.
*/
if (cur->numa_group)
- imp += group_weight(cur, env->src_nid) -
- group_weight(cur, env->dst_nid);
+ imp += group_weight(cur, env->src_nid, dist) -
+ group_weight(cur, env->dst_nid, dist);
else
- imp += task_weight(cur, env->src_nid) -
- task_weight(cur, env->dst_nid);
+ imp += task_weight(cur, env->src_nid, dist) -
+ task_weight(cur, env->dst_nid, dist);
}
}
@@ -1326,7 +1413,7 @@ static int task_numa_migrate(struct task_struct *p)
};
struct sched_domain *sd;
unsigned long taskweight, groupweight;
- int nid, ret;
+ int nid, ret, dist;
long taskimp, groupimp;
/*
@@ -1354,29 +1441,45 @@ static int task_numa_migrate(struct task_struct *p)
return -EINVAL;
}
- taskweight = task_weight(p, env.src_nid);
- groupweight = group_weight(p, env.src_nid);
- update_numa_stats(&env.src_stats, env.src_nid);
env.dst_nid = p->numa_preferred_nid;
- taskimp = task_weight(p, env.dst_nid) - taskweight;
- groupimp = group_weight(p, env.dst_nid) - groupweight;
+ dist = env.dist = node_distance(env.src_nid, env.dst_nid);
+ taskweight = task_weight(p, env.src_nid, dist);
+ groupweight = group_weight(p, env.src_nid, dist);
+ update_numa_stats(&env.src_stats, env.src_nid);
+ taskimp = task_weight(p, env.dst_nid, dist) - taskweight;
+ groupimp = group_weight(p, env.dst_nid, dist) - groupweight;
update_numa_stats(&env.dst_stats, env.dst_nid);
/* Try to find a spot on the preferred nid. */
task_numa_find_cpu(&env, taskimp, groupimp);
- /* No space available on the preferred nid. Look elsewhere. */
- if (env.best_cpu == -1) {
+ /*
+ * Look at other nodes in these cases:
+ * - there is no space available on the preferred_nid
+ * - the task is part of a numa_group that is interleaved across
+ * multiple NUMA nodes; in order to better consolidate the group,
+ * we need to check other locations.
+ */
+ if (env.best_cpu == -1 || (p->numa_group &&
+ nodes_weight(p->numa_group->active_nodes) > 1)) {
for_each_online_node(nid) {
if (nid == env.src_nid || nid == p->numa_preferred_nid)
continue;
+ dist = node_distance(env.src_nid, env.dst_nid);
+ if (sched_numa_topology_type == NUMA_BACKPLANE &&
+ dist != env.dist) {
+ taskweight = task_weight(p, env.src_nid, dist);
+ groupweight = group_weight(p, env.src_nid, dist);
+ }
+
/* Only consider nodes where both task and groups benefit */
- taskimp = task_weight(p, nid) - taskweight;
- groupimp = group_weight(p, nid) - groupweight;
+ taskimp = task_weight(p, nid, dist) - taskweight;
+ groupimp = group_weight(p, nid, dist) - groupweight;
if (taskimp < 0 && groupimp < 0)
continue;
+ env.dist = dist;
env.dst_nid = nid;
update_numa_stats(&env.dst_stats, env.dst_nid);
task_numa_find_cpu(&env, taskimp, groupimp);
@@ -1431,7 +1534,7 @@ static void numa_migrate_preferred(struct task_struct *p)
unsigned long interval = HZ;
/* This task has no NUMA fault statistics yet */
- if (unlikely(p->numa_preferred_nid == -1 || !p->numa_faults_memory))
+ if (unlikely(p->numa_preferred_nid == -1 || !p->numa_faults))
return;
/* Periodically retry migrating the task to the preferred node */
@@ -1580,6 +1683,92 @@ static u64 numa_get_avg_runtime(struct task_struct *p, u64 *period)
return delta;
}
+/*
+ * Determine the preferred nid for a task in a numa_group. This needs to
+ * be done in a way that produces consistent results with group_weight,
+ * otherwise workloads might not converge.
+ */
+static int preferred_group_nid(struct task_struct *p, int nid)
+{
+ nodemask_t nodes;
+ int dist;
+
+ /* Direct connections between all NUMA nodes. */
+ if (sched_numa_topology_type == NUMA_DIRECT)
+ return nid;
+
+ /*
+ * On a system with glueless mesh NUMA topology, group_weight
+ * scores nodes according to the number of NUMA hinting faults on
+ * both the node itself, and on nearby nodes.
+ */
+ if (sched_numa_topology_type == NUMA_GLUELESS_MESH) {
+ unsigned long score, max_score = 0;
+ int node, max_node = nid;
+
+ dist = sched_max_numa_distance;
+
+ for_each_online_node(node) {
+ score = group_weight(p, node, dist);
+ if (score > max_score) {
+ max_score = score;
+ max_node = node;
+ }
+ }
+ return max_node;
+ }
+
+ /*
+ * Finding the preferred nid in a system with NUMA backplane
+ * interconnect topology is more involved. The goal is to locate
+ * tasks from numa_groups near each other in the system, and
+ * untangle workloads from different sides of the system. This requires
+ * searching down the hierarchy of node groups, recursively searching
+ * inside the highest scoring group of nodes. The nodemask tricks
+ * keep the complexity of the search down.
+ */
+ nodes = node_online_map;
+ for (dist = sched_max_numa_distance; dist > LOCAL_DISTANCE; dist--) {
+ unsigned long max_faults = 0;
+ nodemask_t max_group;
+ int a, b;
+
+ /* Are there nodes at this distance from each other? */
+ if (!find_numa_distance(dist))
+ continue;
+
+ for_each_node_mask(a, nodes) {
+ unsigned long faults = 0;
+ nodemask_t this_group;
+ nodes_clear(this_group);
+
+ /* Sum group's NUMA faults; includes a==b case. */
+ for_each_node_mask(b, nodes) {
+ if (node_distance(a, b) < dist) {
+ faults += group_faults(p, b);
+ node_set(b, this_group);
+ node_clear(b, nodes);
+ }
+ }
+
+ /* Remember the top group. */
+ if (faults > max_faults) {
+ max_faults = faults;
+ max_group = this_group;
+ /*
+ * subtle: at the smallest distance there is
+ * just one node left in each "group", the
+ * winner is the preferred nid.
+ */
+ nid = a;
+ }
+ }
+ /* Next round, evaluate the nodes within max_group. */
+ nodes = max_group;
+ }
+ return nid;
+}
+
static void task_numa_placement(struct task_struct *p)
{
int seq, nid, max_nid = -1, max_group_nid = -1;
@@ -1607,18 +1796,23 @@ static void task_numa_placement(struct task_struct *p)
/* Find the node with the highest number of faults */
for_each_online_node(nid) {
+ /* Keep track of the offsets in numa_faults array */
+ int mem_idx, membuf_idx, cpu_idx, cpubuf_idx;
unsigned long faults = 0, group_faults = 0;
- int priv, i;
+ int priv;
for (priv = 0; priv < NR_NUMA_HINT_FAULT_TYPES; priv++) {
long diff, f_diff, f_weight;
- i = task_faults_idx(nid, priv);
+ mem_idx = task_faults_idx(NUMA_MEM, nid, priv);
+ membuf_idx = task_faults_idx(NUMA_MEMBUF, nid, priv);
+ cpu_idx = task_faults_idx(NUMA_CPU, nid, priv);
+ cpubuf_idx = task_faults_idx(NUMA_CPUBUF, nid, priv);
/* Decay existing window, copy faults since last scan */
- diff = p->numa_faults_buffer_memory[i] - p->numa_faults_memory[i] / 2;
- fault_types[priv] += p->numa_faults_buffer_memory[i];
- p->numa_faults_buffer_memory[i] = 0;
+ diff = p->numa_faults[membuf_idx] - p->numa_faults[mem_idx] / 2;
+ fault_types[priv] += p->numa_faults[membuf_idx];
+ p->numa_faults[membuf_idx] = 0;
/*
* Normalize the faults_from, so all tasks in a group
@@ -1628,21 +1822,27 @@ static void task_numa_placement(struct task_struct *p)
* faults are less important.
*/
f_weight = div64_u64(runtime << 16, period + 1);
- f_weight = (f_weight * p->numa_faults_buffer_cpu[i]) /
+ f_weight = (f_weight * p->numa_faults[cpubuf_idx]) /
(total_faults + 1);
- f_diff = f_weight - p->numa_faults_cpu[i] / 2;
- p->numa_faults_buffer_cpu[i] = 0;
+ f_diff = f_weight - p->numa_faults[cpu_idx] / 2;
+ p->numa_faults[cpubuf_idx] = 0;
- p->numa_faults_memory[i] += diff;
- p->numa_faults_cpu[i] += f_diff;
- faults += p->numa_faults_memory[i];
+ p->numa_faults[mem_idx] += diff;
+ p->numa_faults[cpu_idx] += f_diff;
+ faults += p->numa_faults[mem_idx];
p->total_numa_faults += diff;
if (p->numa_group) {
- /* safe because we can only change our own group */
- p->numa_group->faults[i] += diff;
- p->numa_group->faults_cpu[i] += f_diff;
+ /*
+ * safe because we can only change our own group
+ *
+ * mem_idx represents the offset for a given
+ * nid and priv in a specific region because it
+ * is at the beginning of the numa_faults array.
+ */
+ p->numa_group->faults[mem_idx] += diff;
+ p->numa_group->faults_cpu[mem_idx] += f_diff;
p->numa_group->total_faults += diff;
- group_faults += p->numa_group->faults[i];
+ group_faults += p->numa_group->faults[mem_idx];
}
}
@@ -1662,7 +1862,7 @@ static void task_numa_placement(struct task_struct *p)
if (p->numa_group) {
update_numa_active_node_mask(p->numa_group);
spin_unlock_irq(group_lock);
- max_nid = max_group_nid;
+ max_nid = preferred_group_nid(p, max_group_nid);
}
if (max_faults) {
@@ -1705,7 +1905,6 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags,
atomic_set(&grp->refcount, 1);
spin_lock_init(&grp->lock);
- INIT_LIST_HEAD(&grp->task_list);
grp->gid = p->pid;
/* Second half of the array tracks nids where faults happen */
grp->faults_cpu = grp->faults + NR_NUMA_HINT_FAULT_TYPES *
@@ -1714,11 +1913,10 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags,
node_set(task_node(current), grp->active_nodes);
for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++)
- grp->faults[i] = p->numa_faults_memory[i];
+ grp->faults[i] = p->numa_faults[i];
grp->total_faults = p->total_numa_faults;
- list_add(&p->numa_entry, &grp->task_list);
grp->nr_tasks++;
rcu_assign_pointer(p->numa_group, grp);
}
@@ -1773,13 +1971,12 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags,
double_lock_irq(&my_grp->lock, &grp->lock);
for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) {
- my_grp->faults[i] -= p->numa_faults_memory[i];
- grp->faults[i] += p->numa_faults_memory[i];
+ my_grp->faults[i] -= p->numa_faults[i];
+ grp->faults[i] += p->numa_faults[i];
}
my_grp->total_faults -= p->total_numa_faults;
grp->total_faults += p->total_numa_faults;
- list_move(&p->numa_entry, &grp->task_list);
my_grp->nr_tasks--;
grp->nr_tasks++;
@@ -1799,27 +1996,23 @@ no_join:
void task_numa_free(struct task_struct *p)
{
struct numa_group *grp = p->numa_group;
- void *numa_faults = p->numa_faults_memory;
+ void *numa_faults = p->numa_faults;
unsigned long flags;
int i;
if (grp) {
spin_lock_irqsave(&grp->lock, flags);
for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++)
- grp->faults[i] -= p->numa_faults_memory[i];
+ grp->faults[i] -= p->numa_faults[i];
grp->total_faults -= p->total_numa_faults;
- list_del(&p->numa_entry);
grp->nr_tasks--;
spin_unlock_irqrestore(&grp->lock, flags);
RCU_INIT_POINTER(p->numa_group, NULL);
put_numa_group(grp);
}
- p->numa_faults_memory = NULL;
- p->numa_faults_buffer_memory = NULL;
- p->numa_faults_cpu= NULL;
- p->numa_faults_buffer_cpu = NULL;
+ p->numa_faults = NULL;
kfree(numa_faults);
}
@@ -1842,24 +2035,14 @@ void task_numa_fault(int last_cpupid, int mem_node, int pages, int flags)
return;
/* Allocate buffer to track faults on a per-node basis */
- if (unlikely(!p->numa_faults_memory)) {
- int size = sizeof(*p->numa_faults_memory) *
+ if (unlikely(!p->numa_faults)) {
+ int size = sizeof(*p->numa_faults) *
NR_NUMA_HINT_FAULT_BUCKETS * nr_node_ids;
- p->numa_faults_memory = kzalloc(size, GFP_KERNEL|__GFP_NOWARN);
- if (!p->numa_faults_memory)
+ p->numa_faults = kzalloc(size, GFP_KERNEL|__GFP_NOWARN);
+ if (!p->numa_faults)
return;
- BUG_ON(p->numa_faults_buffer_memory);
- /*
- * The averaged statistics, shared & private, memory & cpu,
- * occupy the first half of the array. The second half of the
- * array is for current counters, which are averaged into the
- * first set by task_numa_placement.
- */
- p->numa_faults_cpu = p->numa_faults_memory + (2 * nr_node_ids);
- p->numa_faults_buffer_memory = p->numa_faults_memory + (4 * nr_node_ids);
- p->numa_faults_buffer_cpu = p->numa_faults_memory + (6 * nr_node_ids);
p->total_numa_faults = 0;
memset(p->numa_faults_locality, 0, sizeof(p->numa_faults_locality));
}
@@ -1899,8 +2082,8 @@ void task_numa_fault(int last_cpupid, int mem_node, int pages, int flags)
if (migrated)
p->numa_pages_migrated += pages;
- p->numa_faults_buffer_memory[task_faults_idx(mem_node, priv)] += pages;
- p->numa_faults_buffer_cpu[task_faults_idx(cpu_node, priv)] += pages;
+ p->numa_faults[task_faults_idx(NUMA_MEMBUF, mem_node, priv)] += pages;
+ p->numa_faults[task_faults_idx(NUMA_CPUBUF, cpu_node, priv)] += pages;
p->numa_faults_locality[local] += pages;
}
@@ -4469,7 +4652,7 @@ find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
latest_idle_timestamp = rq->idle_stamp;
shallowest_idle_cpu = i;
}
- } else {
+ } else if (shallowest_idle_cpu == -1) {
load = weighted_cpuload(i);
if (load < min_load || (load == min_load && i == this_cpu)) {
min_load = load;
@@ -4547,9 +4730,6 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f
int want_affine = 0;
int sync = wake_flags & WF_SYNC;
- if (p->nr_cpus_allowed == 1)
- return prev_cpu;
-
if (sd_flag & SD_BALANCE_WAKE)
want_affine = cpumask_test_cpu(cpu, tsk_cpus_allowed(p));
@@ -5189,7 +5369,7 @@ static bool migrate_improves_locality(struct task_struct *p, struct lb_env *env)
struct numa_group *numa_group = rcu_dereference(p->numa_group);
int src_nid, dst_nid;
- if (!sched_feat(NUMA_FAVOUR_HIGHER) || !p->numa_faults_memory ||
+ if (!sched_feat(NUMA_FAVOUR_HIGHER) || !p->numa_faults ||
!(env->sd->flags & SD_NUMA)) {
return false;
}
@@ -5228,7 +5408,7 @@ static bool migrate_degrades_locality(struct task_struct *p, struct lb_env *env)
if (!sched_feat(NUMA) || !sched_feat(NUMA_RESIST_LOWER))
return false;
- if (!p->numa_faults_memory || !(env->sd->flags & SD_NUMA))
+ if (!p->numa_faults || !(env->sd->flags & SD_NUMA))
return false;
src_nid = cpu_to_node(env->src_cpu);
@@ -6172,8 +6352,10 @@ static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sd
* with a large weight task outweighs the tasks on the system).
*/
if (prefer_sibling && sds->local &&
- sds->local_stat.group_has_free_capacity)
+ sds->local_stat.group_has_free_capacity) {
sgs->group_capacity_factor = min(sgs->group_capacity_factor, 1U);
+ sgs->group_type = group_classify(sg, sgs);
+ }
if (update_sd_pick_busiest(env, sds, sg, sgs)) {
sds->busiest = sg;