Commit 9832fb87 authored by Aneesh Kumar K.V's avatar Aneesh Kumar K.V Committed by Andrew Morton
Browse files

mm/demotion: expose memory tier details via sysfs 

Add /sys/devices/virtual/memory_tiering/ where all memory tier related
details can be found.  All allocated memory tiers will be listed there as
/sys/devices/virtual/memory_tiering/memory_tierN/

The nodes which are part of a specific memory tier can be listed via
/sys/devices/virtual/memory_tiering/memory_tierN/nodes

A directory hierarchy looks like
:/sys/devices/virtual/memory_tiering$ tree memory_tier4/
memory_tier4/
├── nodes
├── subsystem -> ../../../../bus/memory_tiering
└── uevent

:/sys/devices/virtual/memory_tiering$ cat memory_tier4/nodes
0,2

[aneesh.kumar@linux.ibm.com: drop toptier_nodes from sysfs]
  Link: https://lkml.kernel.org/r/20220922102201.62168-1-aneesh.kumar@linux.ibm.com
Link: https://lkml.kernel.org/r/20220830081736.119281-1-aneesh.kumar@linux.ibm.com


Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Bharata B Rao <bharata@amd.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Hesham Almatary <hesham.almatary@huawei.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Jagdish Gediya <jvgediya.oss@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Tim Chen <tim.c.chen@intel.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 3e061d92

Documentation/ABI/testing/sysfs-kernel-mm-memory-tiers

0 → 100644
+25 −0
Original line number Diff line number Diff line 
What:		/sys/devices/virtual/memory_tiering/

Date:		August 2022

Contact:	Linux memory management mailing list <linux-mm@kvack.org>

Description:	A collection of all the memory tiers allocated.



		Individual memory tier details are contained in subdirectories

		named by the abstract distance of the memory tier.



		/sys/devices/virtual/memory_tiering/memory_tierN/





What:		/sys/devices/virtual/memory_tiering/memory_tierN/

		/sys/devices/virtual/memory_tiering/memory_tierN/nodes

Date:		August 2022

Contact:	Linux memory management mailing list <linux-mm@kvack.org>

Description:	Directory with details of a specific memory tier



		This is the directory containing information about a particular

		memory tier, memtierN, where N is derived based on abstract distance.



		A smaller value of N implies a higher (faster) memory tier in the

		hierarchy.



		nodes: NUMA nodes that are part of this memory tier.

mm/memory-tiers.c

+87 −22
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ struct memory_tier { 
	 * adistance_start .. adistance_start + MEMTIER_CHUNK_SIZE

	 */

	int adistance_start;

	struct device dev;

	/* All the nodes that are part of all the lower memory tiers. */

	nodemask_t lower_tier_mask;

};
@@ -36,6 +37,12 @@ static DEFINE_MUTEX(memory_tier_lock); 
static LIST_HEAD(memory_tiers);

static struct node_memory_type_map node_memory_types[MAX_NUMNODES];

static struct memory_dev_type *default_dram_type;



static struct bus_type memory_tier_subsys = {

	.name = "memory_tiering",

	.dev_name = "memory_tier",

};



#ifdef CONFIG_MIGRATION

static int top_tier_adistance;

/*
@@ -98,8 +105,63 @@ static int top_tier_adistance; 
static struct demotion_nodes *node_demotion __read_mostly;

#endif /* CONFIG_MIGRATION */



static inline struct memory_tier *to_memory_tier(struct device *device)

{

	return container_of(device, struct memory_tier, dev);

}



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;

}



static void memory_tier_device_release(struct device *dev)

{

	struct memory_tier *tier = to_memory_tier(dev);

	/*

	 * synchronize_rcu in clear_node_memory_tier makes sure

	 * we don't have rcu access to this memory tier.

	 */

	kfree(tier);

}



static ssize_t nodes_show(struct device *dev,

			  struct device_attribute *attr, char *buf)

{

	int ret;

	nodemask_t nmask;



	mutex_lock(&memory_tier_lock);

	nmask = get_memtier_nodemask(to_memory_tier(dev));

	ret = sysfs_emit(buf, "%*pbl\n", nodemask_pr_args(&nmask));

	mutex_unlock(&memory_tier_lock);

	return ret;

}

static DEVICE_ATTR_RO(nodes);



static struct attribute *memtier_dev_attrs[] = {

	&dev_attr_nodes.attr,

	NULL

};



static const struct attribute_group memtier_dev_group = {

	.attrs = memtier_dev_attrs,

};



static const struct attribute_group *memtier_dev_groups[] = {

	&memtier_dev_group,

	NULL

};



static struct memory_tier *find_create_memory_tier(struct memory_dev_type *memtype)

{

	int ret;

	bool found_slot = false;

	struct memory_tier *memtier, *new_memtier;

	int adistance = memtype->adistance;
@@ -123,15 +185,14 @@ static struct memory_tier *find_create_memory_tier(struct memory_dev_type *memty 


	list_for_each_entry(memtier, &memory_tiers, list) {

		if (adistance == memtier->adistance_start) {

			list_add(&memtype->tier_sibiling, &memtier->memory_types);

			return memtier;

			goto link_memtype;

		} else if (adistance < memtier->adistance_start) {

			found_slot = true;

			break;

		}

	}



	new_memtier = kmalloc(sizeof(struct memory_tier), GFP_KERNEL);

	new_memtier = kzalloc(sizeof(struct memory_tier), GFP_KERNEL);

	if (!new_memtier)

		return ERR_PTR(-ENOMEM);
@@ -142,8 +203,23 @@ static struct memory_tier *find_create_memory_tier(struct memory_dev_type *memty 
		list_add_tail(&new_memtier->list, &memtier->list);

	else

		list_add_tail(&new_memtier->list, &memory_tiers);

	list_add(&memtype->tier_sibiling, &new_memtier->memory_types);

	return new_memtier;



	new_memtier->dev.id = adistance >> MEMTIER_CHUNK_BITS;

	new_memtier->dev.bus = &memory_tier_subsys;

	new_memtier->dev.release = memory_tier_device_release;

	new_memtier->dev.groups = memtier_dev_groups;



	ret = device_register(&new_memtier->dev);

	if (ret) {

		list_del(&memtier->list);

		put_device(&memtier->dev);

		return ERR_PTR(ret);

	}

	memtier = new_memtier;



link_memtype:

	list_add(&memtype->tier_sibiling, &memtier->memory_types);

	return memtier;

}



static struct memory_tier *__node_get_memory_tier(int node)
@@ -275,17 +351,6 @@ static void disable_all_demotion_targets(void) 
	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
@@ -433,11 +498,7 @@ static struct memory_tier *set_node_memory_tier(int node) 
static void destroy_memory_tier(struct memory_tier *memtier)

{

	list_del(&memtier->list);

	/*

	 * synchronize_rcu in clear_node_memory_tier makes sure

	 * we don't have rcu access to this memory tier.

	 */

	kfree(memtier);

	device_unregister(&memtier->dev);

}



static bool clear_node_memory_tier(int node)
@@ -566,9 +627,13 @@ static int __meminit memtier_hotplug_callback(struct notifier_block *self, 


static int __init memory_tier_init(void)

{

	int node;

	int ret, node;

	struct memory_tier *memtier;



	ret = subsys_virtual_register(&memory_tier_subsys, NULL);

	if (ret)

		panic("%s() failed to register memory tier subsystem\n", __func__);



#ifdef CONFIG_MIGRATION

	node_demotion = kcalloc(nr_node_ids, sizeof(struct demotion_nodes),

				GFP_KERNEL);