[PATCH v6 06/13] mm/demotion: Expose memory tier details via sysfs

Aneesh Kumar K.V
2022-06-10T13:55:06Z

This patch adds /sys/devices/system/memtier/ where all memory tier
related details can be found. All created memory tiers will be
listed there as /sys/devices/system/memtier/memtierN/

The nodes which are part of a specific memory tier can be listed
via /sys/devices/system/memtier/memtierN/nodelist

The rank value of a memory tier can be listed via
via /sys/devices/system/memtier/memtierN/rank

/sys/devices/system/memtier/max_tier shows the maximum number of memory
tiers that can be created.

/sys/devices/system/memtier/default_tier shows the memory tier to which
NUMA nodes get added by default if not assigned a specific memory tier.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
---
mm/memory-tiers.c | 99 +++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 95 insertions(+), 4 deletions(-)

diff --git a/mm/memory-tiers.c b/mm/memory-tiers.c
index 2f116912de43..51210f5efc1f 100644
--- a/mm/memory-tiers.c
+++ b/mm/memory-tiers.c
@@ -11,8 +11,8 @@

struct memory_tier {
struct list_head list;
+ struct device dev;
nodemask_t nodelist;
- int id;
int rank;
};

@@ -20,6 +20,7 @@ struct demotion_nodes {
nodemask_t preferred;
};

+#define to_memory_tier(device) container_of(device, struct memory_tier, dev)
static void establish_migration_targets(void);
static DEFINE_MUTEX(memory_tier_lock);
static LIST_HEAD(memory_tiers);
@@ -86,6 +87,52 @@ static LIST_HEAD(memory_tiers);
*/
static struct demotion_nodes *node_demotion __read_mostly;

+static struct bus_type memory_tier_subsys = {
+ .name = "memtier",
+ .dev_name = "memtier",
+};
+
+static ssize_t nodelist_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct memory_tier *memtier = to_memory_tier(dev);
+
+ return sysfs_emit(buf, "%*pbl\n",
+ nodemask_pr_args(&memtier->nodelist));
+}
+static DEVICE_ATTR_RO(nodelist);
+
+static ssize_t rank_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct memory_tier *memtier = to_memory_tier(dev);
+
+ return sysfs_emit(buf, "%d\n", memtier->rank);
+}
+static DEVICE_ATTR_RO(rank);
+
+static struct attribute *memory_tier_dev_attrs[] = {
+ &dev_attr_nodelist.attr,
+ &dev_attr_rank.attr,
+ NULL
+};
+
+static const struct attribute_group memory_tier_dev_group = {
+ .attrs = memory_tier_dev_attrs,
+};
+
+static const struct attribute_group *memory_tier_dev_groups[] = {
+ &memory_tier_dev_group,
+ NULL
+};
+
+static void memory_tier_device_release(struct device *dev)
+{
+ struct memory_tier *tier = to_memory_tier(dev);
+
+ kfree(tier);
+}
+
/*
* Keep it simple by having direct mapping between
* tier index and rank value.
@@ -121,6 +168,7 @@ static void insert_memory_tier(struct memory_tier *memtier)
static struct memory_tier *register_memory_tier(unsigned int tier,
unsigned int rank)
{
+ int error;
struct memory_tier *memtier;

if (tier >= MAX_MEMORY_TIERS)
@@ -130,11 +178,20 @@ static struct memory_tier *register_memory_tier(unsigned int tier,
if (!memtier)
return ERR_PTR(-ENOMEM);

- memtier->id = tier;
+ memtier->dev.id = tier;
memtier->rank = rank;
+ memtier->dev.bus = &memory_tier_subsys;
+ memtier->dev.release = memory_tier_device_release;
+ memtier->dev.groups = memory_tier_dev_groups;

insert_memory_tier(memtier);

+ error = device_register(&memtier->dev);
+ if (error) {
+ list_del(&memtier->list);
+ put_device(&memtier->dev);
+ return ERR_PTR(error);
+ }
return memtier;
}

@@ -154,7 +211,7 @@ static struct memory_tier *__get_memory_tier_from_id(int id)
struct memory_tier *memtier;

list_for_each_entry(memtier, &memory_tiers, list) {
- if (memtier->id == id)
+ if (memtier->dev.id == id)
return memtier;
}
return NULL;
@@ -199,7 +256,7 @@ int node_create_and_set_memory_tier(int node, int tier)
goto out;
}

- if (current_tier->id == tier)
+ if (current_tier->dev.id == tier)
goto out;

node_clear(node, current_tier->nodelist);
@@ -435,10 +492,44 @@ static void __init migrate_on_reclaim_init(void)
hotplug_memory_notifier(migrate_on_reclaim_callback, 100);
}

+static ssize_t
+max_tier_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ return sysfs_emit(buf, "%d\n", MAX_MEMORY_TIERS);
+}
+static DEVICE_ATTR_RO(max_tier);
+
+static ssize_t
+default_tier_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ return sysfs_emit(buf, "memtier%d\n", DEFAULT_MEMORY_TIER);
+}
+static DEVICE_ATTR_RO(default_tier);
+
+static struct attribute *memory_tier_attrs[] = {
+ &dev_attr_max_tier.attr,
+ &dev_attr_default_tier.attr,
+ NULL
+};
+
+static const struct attribute_group memory_tier_attr_group = {
+ .attrs = memory_tier_attrs,
+};
+
+static const struct attribute_group *memory_tier_attr_groups[] = {
+ &memory_tier_attr_group,
+ NULL,
+};
+
static int __init memory_tier_init(void)
{
+ int ret;
struct memory_tier *memtier;

+ ret = subsys_system_register(&memory_tier_subsys, memory_tier_attr_groups);
+ if (ret)
+ pr_err("%s() failed to register subsystem: %d\n", __func__, ret);
+
/*
* Register only default memory tier to hide all empty
* memory tier from sysfs.
--
2.36.1