#include <linux/memory.h>
#include <linux/memory-tiers.h>
+#include "internal.h"
+
struct memory_tier {
/* hierarchy of memory tiers */
struct list_head list;
int adistance_start;
};
+struct demotion_nodes {
+ nodemask_t preferred;
+};
+
struct node_memory_type_map {
struct memory_dev_type *memtype;
int map_count;
static LIST_HEAD(memory_tiers);
static struct node_memory_type_map node_memory_types[MAX_NUMNODES];
static struct memory_dev_type *default_dram_type;
+#ifdef CONFIG_MIGRATION
+/*
+ * node_demotion[] examples:
+ *
+ * Example 1:
+ *
+ * Node 0 & 1 are CPU + DRAM nodes, node 2 & 3 are PMEM nodes.
+ *
+ * node distances:
+ * node 0 1 2 3
+ * 0 10 20 30 40
+ * 1 20 10 40 30
+ * 2 30 40 10 40
+ * 3 40 30 40 10
+ *
+ * memory_tiers0 = 0-1
+ * memory_tiers1 = 2-3
+ *
+ * node_demotion[0].preferred = 2
+ * node_demotion[1].preferred = 3
+ * node_demotion[2].preferred = <empty>
+ * node_demotion[3].preferred = <empty>
+ *
+ * Example 2:
+ *
+ * Node 0 & 1 are CPU + DRAM nodes, node 2 is memory-only DRAM node.
+ *
+ * node distances:
+ * node 0 1 2
+ * 0 10 20 30
+ * 1 20 10 30
+ * 2 30 30 10
+ *
+ * memory_tiers0 = 0-2
+ *
+ * node_demotion[0].preferred = <empty>
+ * node_demotion[1].preferred = <empty>
+ * node_demotion[2].preferred = <empty>
+ *
+ * Example 3:
+ *
+ * Node 0 is CPU + DRAM nodes, Node 1 is HBM node, node 2 is PMEM node.
+ *
+ * node distances:
+ * node 0 1 2
+ * 0 10 20 30
+ * 1 20 10 40
+ * 2 30 40 10
+ *
+ * memory_tiers0 = 1
+ * memory_tiers1 = 0
+ * memory_tiers2 = 2
+ *
+ * node_demotion[0].preferred = 2
+ * node_demotion[1].preferred = 0
+ * node_demotion[2].preferred = <empty>
+ *
+ */
+static struct demotion_nodes *node_demotion __read_mostly;
+#endif /* CONFIG_MIGRATION */
static struct memory_tier *find_create_memory_tier(struct memory_dev_type *memtype)
{
return new_memtier;
}
+static struct memory_tier *__node_get_memory_tier(int node)
+{
+ struct memory_dev_type *memtype;
+
+ memtype = node_memory_types[node];
+ if (memtype && node_isset(node, memtype->nodes))
+ return memtype->memtier;
+ return NULL;
+}
+
+#ifdef CONFIG_MIGRATION
+/**
+ * next_demotion_node() - Get the next node in the demotion path
+ * @node: The starting node to lookup the next node
+ *
+ * Return: node id for next memory node in the demotion path hierarchy
+ * from @node; NUMA_NO_NODE if @node is terminal. This does not keep
+ * @node online or guarantee that it *continues* to be the next demotion
+ * target.
+ */
+int next_demotion_node(int node)
+{
+ struct demotion_nodes *nd;
+ int target;
+
+ if (!node_demotion)
+ return NUMA_NO_NODE;
+
+ nd = &node_demotion[node];
+
+ /*
+ * node_demotion[] is updated without excluding this
+ * function from running.
+ *
+ * Make sure to use RCU over entire code blocks if
+ * node_demotion[] reads need to be consistent.
+ */
+ rcu_read_lock();
+ /*
+ * If there are multiple target nodes, just select one
+ * target node randomly.
+ *
+ * In addition, we can also use round-robin to select
+ * target node, but we should introduce another variable
+ * for node_demotion[] to record last selected target node,
+ * that may cause cache ping-pong due to the changing of
+ * last target node. Or introducing per-cpu data to avoid
+ * caching issue, which seems more complicated. So selecting
+ * target node randomly seems better until now.
+ */
+ target = node_random(&nd->preferred);
+ rcu_read_unlock();
+
+ return target;
+}
+
+static void disable_all_demotion_targets(void)
+{
+ int node;
+
+ for_each_node_state(node, N_MEMORY)
+ node_demotion[node].preferred = NODE_MASK_NONE;
+ /*
+ * Ensure that the "disable" is visible across the system.
+ * Readers will see either a combination of before+disable
+ * state or disable+after. They will never see before and
+ * after state together.
+ */
+ synchronize_rcu();
+}
+
+static __always_inline nodemask_t get_memtier_nodemask(struct memory_tier *memtier)
+{
+ nodemask_t nodes = NODE_MASK_NONE;
+ struct memory_dev_type *memtype;
+
+ list_for_each_entry(memtype, &memtier->memory_types, tier_sibiling)
+ nodes_or(nodes, nodes, memtype->nodes);
+
+ return nodes;
+}
+
+/*
+ * Find an automatic demotion target for all memory
+ * nodes. Failing here is OK. It might just indicate
+ * being at the end of a chain.
+ */
+static void establish_demotion_targets(void)
+{
+ struct memory_tier *memtier;
+ struct demotion_nodes *nd;
+ int target = NUMA_NO_NODE, node;
+ int distance, best_distance;
+ nodemask_t tier_nodes;
+
+ lockdep_assert_held_once(&memory_tier_lock);
+
+ if (!node_demotion || !IS_ENABLED(CONFIG_MIGRATION))
+ return;
+
+ disable_all_demotion_targets();
+
+ for_each_node_state(node, N_MEMORY) {
+ best_distance = -1;
+ nd = &node_demotion[node];
+
+ memtier = __node_get_memory_tier(node);
+ if (!memtier || list_is_last(&memtier->list, &memory_tiers))
+ continue;
+ /*
+ * Get the lower memtier to find the demotion node list.
+ */
+ memtier = list_next_entry(memtier, list);
+ tier_nodes = get_memtier_nodemask(memtier);
+ /*
+ * find_next_best_node, use 'used' nodemask as a skip list.
+ * Add all memory nodes except the selected memory tier
+ * nodelist to skip list so that we find the best node from the
+ * memtier nodelist.
+ */
+ nodes_andnot(tier_nodes, node_states[N_MEMORY], tier_nodes);
+
+ /*
+ * Find all the nodes in the memory tier node list of same best distance.
+ * add them to the preferred mask. We randomly select between nodes
+ * in the preferred mask when allocating pages during demotion.
+ */
+ do {
+ target = find_next_best_node(node, &tier_nodes);
+ if (target == NUMA_NO_NODE)
+ break;
+
+ distance = node_distance(node, target);
+ if (distance == best_distance || best_distance == -1) {
+ best_distance = distance;
+ node_set(target, nd->preferred);
+ } else {
+ break;
+ }
+ } while (1);
+ }
+}
+
+#else
+static inline void disable_all_demotion_targets(void) {}
+static inline void establish_demotion_targets(void) {}
+#endif /* CONFIG_MIGRATION */
+
static inline void __init_node_memory_type(int node, struct memory_dev_type *memtype)
{
if (!node_memory_types[node].memtype)
return memtier;
}
-static struct memory_tier *__node_get_memory_tier(int node)
-{
- struct memory_dev_type *memtype;
-
- memtype = node_memory_types[node];
- if (memtype && node_isset(node, memtype->nodes))
- return memtype->memtier;
- return NULL;
-}
-
static void destroy_memory_tier(struct memory_tier *memtier)
{
list_del(&memtier->list);
static int __meminit memtier_hotplug_callback(struct notifier_block *self,
unsigned long action, void *_arg)
{
+ struct memory_tier *memtier;
struct memory_notify *arg = _arg;
/*
switch (action) {
case MEM_OFFLINE:
mutex_lock(&memory_tier_lock);
- clear_node_memory_tier(arg->status_change_nid);
+ if (clear_node_memory_tier(arg->status_change_nid))
+ establish_demotion_targets();
mutex_unlock(&memory_tier_lock);
break;
case MEM_ONLINE:
mutex_lock(&memory_tier_lock);
- set_node_memory_tier(arg->status_change_nid);
+ memtier = set_node_memory_tier(arg->status_change_nid);
+ if (!IS_ERR(memtier))
+ establish_demotion_targets();
mutex_unlock(&memory_tier_lock);
break;
}
int node;
struct memory_tier *memtier;
+#ifdef CONFIG_MIGRATION
+ node_demotion = kcalloc(nr_node_ids, sizeof(struct demotion_nodes),
+ GFP_KERNEL);
+ WARN_ON(!node_demotion);
+#endif
mutex_lock(&memory_tier_lock);
/*
* For now we can have 4 faster memory tiers with smaller adistance
*/
break;
}
+ establish_demotion_targets();
mutex_unlock(&memory_tier_lock);
hotplug_memory_notifier(memtier_hotplug_callback, MEMTIER_HOTPLUG_PRIO);
return 0;
}
#endif /* CONFIG_NUMA_BALANCING */
-
-/*
- * node_demotion[] example:
- *
- * Consider a system with two sockets. Each socket has
- * three classes of memory attached: fast, medium and slow.
- * Each memory class is placed in its own NUMA node. The
- * CPUs are placed in the node with the "fast" memory. The
- * 6 NUMA nodes (0-5) might be split among the sockets like
- * this:
- *
- * Socket A: 0, 1, 2
- * Socket B: 3, 4, 5
- *
- * When Node 0 fills up, its memory should be migrated to
- * Node 1. When Node 1 fills up, it should be migrated to
- * Node 2. The migration path start on the nodes with the
- * processors (since allocations default to this node) and
- * fast memory, progress through medium and end with the
- * slow memory:
- *
- * 0 -> 1 -> 2 -> stop
- * 3 -> 4 -> 5 -> stop
- *
- * This is represented in the node_demotion[] like this:
- *
- * { nr=1, nodes[0]=1 }, // Node 0 migrates to 1
- * { nr=1, nodes[0]=2 }, // Node 1 migrates to 2
- * { nr=0, nodes[0]=-1 }, // Node 2 does not migrate
- * { nr=1, nodes[0]=4 }, // Node 3 migrates to 4
- * { nr=1, nodes[0]=5 }, // Node 4 migrates to 5
- * { nr=0, nodes[0]=-1 }, // Node 5 does not migrate
- *
- * Moreover some systems may have multiple slow memory nodes.
- * Suppose a system has one socket with 3 memory nodes, node 0
- * is fast memory type, and node 1/2 both are slow memory
- * type, and the distance between fast memory node and slow
- * memory node is same. So the migration path should be:
- *
- * 0 -> 1/2 -> stop
- *
- * This is represented in the node_demotion[] like this:
- * { nr=2, {nodes[0]=1, nodes[1]=2} }, // Node 0 migrates to node 1 and node 2
- * { nr=0, nodes[0]=-1, }, // Node 1 dose not migrate
- * { nr=0, nodes[0]=-1, }, // Node 2 does not migrate
- */
-
-/*
- * Writes to this array occur without locking. Cycles are
- * not allowed: Node X demotes to Y which demotes to X...
- *
- * If multiple reads are performed, a single rcu_read_lock()
- * must be held over all reads to ensure that no cycles are
- * observed.
- */
-#define DEFAULT_DEMOTION_TARGET_NODES 15
-
-#if MAX_NUMNODES < DEFAULT_DEMOTION_TARGET_NODES
-#define DEMOTION_TARGET_NODES (MAX_NUMNODES - 1)
-#else
-#define DEMOTION_TARGET_NODES DEFAULT_DEMOTION_TARGET_NODES
-#endif
-
-struct demotion_nodes {
- unsigned short nr;
- short nodes[DEMOTION_TARGET_NODES];
-};
-
-static struct demotion_nodes *node_demotion __read_mostly;
-
-/**
- * next_demotion_node() - Get the next node in the demotion path
- * @node: The starting node to lookup the next node
- *
- * Return: node id for next memory node in the demotion path hierarchy
- * from @node; NUMA_NO_NODE if @node is terminal. This does not keep
- * @node online or guarantee that it *continues* to be the next demotion
- * target.
- */
-int next_demotion_node(int node)
-{
- struct demotion_nodes *nd;
- unsigned short target_nr, index;
- int target;
-
- if (!node_demotion)
- return NUMA_NO_NODE;
-
- nd = &node_demotion[node];
-
- /*
- * node_demotion[] is updated without excluding this
- * function from running. RCU doesn't provide any
- * compiler barriers, so the READ_ONCE() is required
- * to avoid compiler reordering or read merging.
- *
- * Make sure to use RCU over entire code blocks if
- * node_demotion[] reads need to be consistent.
- */
- rcu_read_lock();
- target_nr = READ_ONCE(nd->nr);
-
- switch (target_nr) {
- case 0:
- target = NUMA_NO_NODE;
- goto out;
- case 1:
- index = 0;
- break;
- default:
- /*
- * If there are multiple target nodes, just select one
- * target node randomly.
- *
- * In addition, we can also use round-robin to select
- * target node, but we should introduce another variable
- * for node_demotion[] to record last selected target node,
- * that may cause cache ping-pong due to the changing of
- * last target node. Or introducing per-cpu data to avoid
- * caching issue, which seems more complicated. So selecting
- * target node randomly seems better until now.
- */
- index = get_random_int() % target_nr;
- break;
- }
-
- target = READ_ONCE(nd->nodes[index]);
-
-out:
- rcu_read_unlock();
- return target;
-}
-
-/* Disable reclaim-based migration. */
-static void __disable_all_migrate_targets(void)
-{
- int node, i;
-
- if (!node_demotion)
- return;
-
- for_each_online_node(node) {
- node_demotion[node].nr = 0;
- for (i = 0; i < DEMOTION_TARGET_NODES; i++)
- node_demotion[node].nodes[i] = NUMA_NO_NODE;
- }
-}
-
-static void disable_all_migrate_targets(void)
-{
- __disable_all_migrate_targets();
-
- /*
- * Ensure that the "disable" is visible across the system.
- * Readers will see either a combination of before+disable
- * state or disable+after. They will never see before and
- * after state together.
- *
- * The before+after state together might have cycles and
- * could cause readers to do things like loop until this
- * function finishes. This ensures they can only see a
- * single "bad" read and would, for instance, only loop
- * once.
- */
- synchronize_rcu();
-}
-
-/*
- * Find an automatic demotion target for 'node'.
- * Failing here is OK. It might just indicate
- * being at the end of a chain.
- */
-static int establish_migrate_target(int node, nodemask_t *used,
- int best_distance)
-{
- int migration_target, index, val;
- struct demotion_nodes *nd;
-
- if (!node_demotion)
- return NUMA_NO_NODE;
-
- nd = &node_demotion[node];
-
- migration_target = find_next_best_node(node, used);
- if (migration_target == NUMA_NO_NODE)
- return NUMA_NO_NODE;
-
- /*
- * If the node has been set a migration target node before,
- * which means it's the best distance between them. Still
- * check if this node can be demoted to other target nodes
- * if they have a same best distance.
- */
- if (best_distance != -1) {
- val = node_distance(node, migration_target);
- if (val > best_distance)
- goto out_clear;
- }
-
- index = nd->nr;
- if (WARN_ONCE(index >= DEMOTION_TARGET_NODES,
- "Exceeds maximum demotion target nodes\n"))
- goto out_clear;
-
- nd->nodes[index] = migration_target;
- nd->nr++;
-
- return migration_target;
-out_clear:
- node_clear(migration_target, *used);
- return NUMA_NO_NODE;
-}
-
-/*
- * When memory fills up on a node, memory contents can be
- * automatically migrated to another node instead of
- * discarded at reclaim.
- *
- * Establish a "migration path" which will start at nodes
- * with CPUs and will follow the priorities used to build the
- * page allocator zonelists.
- *
- * The difference here is that cycles must be avoided. If
- * node0 migrates to node1, then neither node1, nor anything
- * node1 migrates to can migrate to node0. Also one node can
- * be migrated to multiple nodes if the target nodes all have
- * a same best-distance against the source node.
- *
- * This function can run simultaneously with readers of
- * node_demotion[]. However, it can not run simultaneously
- * with itself. Exclusion is provided by memory hotplug events
- * being single-threaded.
- */
-static void __set_migration_target_nodes(void)
-{
- nodemask_t next_pass;
- nodemask_t this_pass;
- nodemask_t used_targets = NODE_MASK_NONE;
- int node, best_distance;
-
- /*
- * Avoid any oddities like cycles that could occur
- * from changes in the topology. This will leave
- * a momentary gap when migration is disabled.
- */
- disable_all_migrate_targets();
-
- /*
- * Allocations go close to CPUs, first. Assume that
- * the migration path starts at the nodes with CPUs.
- */
- next_pass = node_states[N_CPU];
-again:
- this_pass = next_pass;
- next_pass = NODE_MASK_NONE;
- /*
- * To avoid cycles in the migration "graph", ensure
- * that migration sources are not future targets by
- * setting them in 'used_targets'. Do this only
- * once per pass so that multiple source nodes can
- * share a target node.
- *
- * 'used_targets' will become unavailable in future
- * passes. This limits some opportunities for
- * multiple source nodes to share a destination.
- */
- nodes_or(used_targets, used_targets, this_pass);
-
- for_each_node_mask(node, this_pass) {
- best_distance = -1;
-
- /*
- * Try to set up the migration path for the node, and the target
- * migration nodes can be multiple, so doing a loop to find all
- * the target nodes if they all have a best node distance.
- */
- do {
- int target_node =
- establish_migrate_target(node, &used_targets,
- best_distance);
-
- if (target_node == NUMA_NO_NODE)
- break;
-
- if (best_distance == -1)
- best_distance = node_distance(node, target_node);
-
- /*
- * Visit targets from this pass in the next pass.
- * Eventually, every node will have been part of
- * a pass, and will become set in 'used_targets'.
- */
- node_set(target_node, next_pass);
- } while (1);
- }
- /*
- * 'next_pass' contains nodes which became migration
- * targets in this pass. Make additional passes until
- * no more migrations targets are available.
- */
- if (!nodes_empty(next_pass))
- goto again;
-}
-
-/*
- * For callers that do not hold get_online_mems() already.
- */
-void set_migration_target_nodes(void)
-{
- get_online_mems();
- __set_migration_target_nodes();
- put_online_mems();
-}
-
-/*
- * This leaves migrate-on-reclaim transiently disabled between
- * the MEM_GOING_OFFLINE and MEM_OFFLINE events. This runs
- * whether reclaim-based migration is enabled or not, which
- * ensures that the user can turn reclaim-based migration at
- * any time without needing to recalculate migration targets.
- *
- * These callbacks already hold get_online_mems(). That is why
- * __set_migration_target_nodes() can be used as opposed to
- * set_migration_target_nodes().
- */
-#ifdef CONFIG_MEMORY_HOTPLUG
-static int __meminit migrate_on_reclaim_callback(struct notifier_block *self,
- unsigned long action, void *_arg)
-{
- struct memory_notify *arg = _arg;
-
- /*
- * Only update the node migration order when a node is
- * changing status, like online->offline. This avoids
- * the overhead of synchronize_rcu() in most cases.
- */
- if (arg->status_change_nid < 0)
- return notifier_from_errno(0);
-
- switch (action) {
- case MEM_GOING_OFFLINE:
- /*
- * Make sure there are not transient states where
- * an offline node is a migration target. This
- * will leave migration disabled until the offline
- * completes and the MEM_OFFLINE case below runs.
- */
- disable_all_migrate_targets();
- break;
- case MEM_OFFLINE:
- case MEM_ONLINE:
- /*
- * Recalculate the target nodes once the node
- * reaches its final state (online or offline).
- */
- __set_migration_target_nodes();
- break;
- case MEM_CANCEL_OFFLINE:
- /*
- * MEM_GOING_OFFLINE disabled all the migration
- * targets. Reenable them.
- */
- __set_migration_target_nodes();
- break;
- case MEM_GOING_ONLINE:
- case MEM_CANCEL_ONLINE:
- break;
- }
-
- return notifier_from_errno(0);
-}
-#endif
-
-void __init migrate_on_reclaim_init(void)
-{
- node_demotion = kcalloc(nr_node_ids,
- sizeof(struct demotion_nodes),
- GFP_KERNEL);
- WARN_ON(!node_demotion);
-#ifdef CONFIG_MEMORY_HOTPLUG
- hotplug_memory_notifier(migrate_on_reclaim_callback, 100);
-#endif
- /*
- * At this point, all numa nodes with memory/CPus have their state
- * properly set, so we can build the demotion order now.
- * Let us hold the cpu_hotplug lock just, as we could possibily have
- * CPU hotplug events during boot.
- */
- cpus_read_lock();
- set_migration_target_nodes();
- cpus_read_unlock();
-}
#endif /* CONFIG_NUMA */
-
-
projects / kernel.git / commitdiff