On 8/30/22 12:01 PM, Wei Xu wrote: > On Sun, Aug 28, 2022 at 11:08 PM Aneesh Kumar K.V > <aneesh.kumar@xxxxxxxxxxxxx> wrote: >> >> This patch adds /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 >> >> The abstract distance range value of a specific memory tier can be listed via >> /sys/devices/virtual/memory_tiering/memory_tierN/abstract_distance >> >> A directory hierarchy looks like >> :/sys/devices/virtual/memory_tiering$ tree memory_tier4/ >> memory_tier4/ >> ├── abstract_distance >> ├── nodes >> ├── subsystem -> ../../../../bus/memory_tiering >> └── uevent >> >> All toptier nodes are listed via >> /sys/devices/virtual/memory_tiering/toptier_nodes >> >> :/sys/devices/virtual/memory_tiering$ cat toptier_nodes >> 0,2 >> :/sys/devices/virtual/memory_tiering$ cat memory_tier4/nodes >> 0,2 >> :/sys/devices/virtual/memory_tiering$ cat memory_tier4/abstract_distance >> 512 - 639 >> >> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx> >> --- >> .../ABI/testing/sysfs-kernel-mm-memory-tiers | 41 +++++ >> mm/memory-tiers.c | 155 +++++++++++++++--- >> 2 files changed, 174 insertions(+), 22 deletions(-) >> create mode 100644 Documentation/ABI/testing/sysfs-kernel-mm-memory-tiers >> >> diff --git a/Documentation/ABI/testing/sysfs-kernel-mm-memory-tiers b/Documentation/ABI/testing/sysfs-kernel-mm-memory-tiers >> new file mode 100644 >> index 000000000000..6955f69a4423 >> --- /dev/null >> +++ b/Documentation/ABI/testing/sysfs-kernel-mm-memory-tiers >> @@ -0,0 +1,41 @@ >> +What: /sys/devices/virtual/memory_tiering/ >> +Date: August 2022 >> +Contact: Linux memory management mailing list <linux-mm@xxxxxxxxx> >> +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/abstract_distance >> + /sys/devices/virtual/memory_tiering/memory_tierN/nodes >> +Date: August 2022 >> +Contact: Linux memory management mailing list <linux-mm@xxxxxxxxx> >> +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. > > Given that abstract_distance is provided, it would be more flexible if > we don't commit to the interface where N in memtierN also indicates > the memory tier ordering. IIUC this is one of the request that Johannes had ie, to be able to understand the memory tier hierarchy based on memtier name. >> + >> + abstract_distance: The abstract distance range this specific memory >> + tier maps to. > > I still think the name of "abstract distance" is kind of confusing > because it is not clear what is the other object that this distance > value is relative to. Do we have to expose this value at this point > if N in memtierN can already indicate the memory tier ordering? > I do agree that abstract distance is confusing. But IIUC we agreed that it is much better than other names suggested and is closer to already understood "numa distance" term. https://lore.kernel.org/linux-mm/YuLF%2FGG8x5lQvg%2Ff@xxxxxxxxxxx/ >> + nodes: NUMA nodes that are part of this memory tier. >> + >> + >> +What: /sys/devices/virtual/memory_tiering/toptier_nodes >> +Date: August 2022 >> +Contact: Linux memory management mailing list <linux-mm@xxxxxxxxx> >> +Description: Toptier node mask >> + >> + A toptier is defined as the memory tier from which memory promotion >> + is not done by the kernel. >> + >> + toptier_nodes: NUMA nodes that are part of all the memory tiers >> + above a topier tier. > > Nit: topier -> toptier > > toptier_nodes should be the union of NUMA nodes that are part of each > toptier, not above a toptier, right? > I will update the wording. Yes. it is the union of NUMA nodes that are part of each toptier. >> + >> diff --git a/mm/memory-tiers.c b/mm/memory-tiers.c >> index c4bd6d052a33..d4648d4e4d54 100644 >> --- a/mm/memory-tiers.c >> +++ b/mm/memory-tiers.c >> @@ -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 +37,13 @@ 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; >> + >> +#define to_memory_tier(device) container_of(device, struct memory_tier, dev) >> +static struct bus_type memory_tier_subsys = { >> + .name = "memory_tiering", >> + .dev_name = "memory_tier", >> +}; >> + >> #ifdef CONFIG_MIGRATION >> static int top_tier_adistance; >> /* >> @@ -98,8 +106,73 @@ static int top_tier_adistance; >> static struct demotion_nodes *node_demotion __read_mostly; >> #endif /* CONFIG_MIGRATION */ >> >> +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 ssize_t abstract_distance_show(struct device *dev, >> + struct device_attribute *attr, char *buf) >> +{ >> + int ret; >> + struct memory_tier *memtier = to_memory_tier(dev); >> + >> + mutex_lock(&memory_tier_lock); >> + ret = sysfs_emit(buf, "%d - %d\n", memtier->adistance_start, >> + memtier->adistance_start + MEMTIER_CHUNK_SIZE - 1); >> + mutex_unlock(&memory_tier_lock); >> + return ret; >> +} >> +static DEVICE_ATTR_RO(abstract_distance); >> + >> +static struct attribute *memtier_dev_attrs[] = { >> + &dev_attr_nodes.attr, >> + &dev_attr_abstract_distance.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 +196,14 @@ 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 +214,23 @@ 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 +362,6 @@ 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 >> @@ -432,11 +508,7 @@ 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) >> @@ -563,11 +635,50 @@ static int __meminit memtier_hotplug_callback(struct notifier_block *self, >> return notifier_from_errno(0); >> } >> >> +static ssize_t toptier_nodes_show(struct device *dev, >> + struct device_attribute *attr, char *buf) >> +{ >> + int ret; >> + nodemask_t nmask, top_tier_mask = NODE_MASK_NONE; >> + struct memory_tier *memtier = to_memory_tier(dev); >> + >> + mutex_lock(&memory_tier_lock); >> + list_for_each_entry(memtier, &memory_tiers, list) { >> + if (memtier->adistance_start >= top_tier_adistance) > > It is kind of confusing that a tier with top_tier_adistance is not > considered as a toptier. Can we redefine top_tier_adistance to be the > inclusive upper bound of toptiers? > Agreed. I will fix that up by doing top_tier_adistance = memtier->adistance_start + MEMTIER_CHUNK_SIZE - 1; >> + break; >> + nmask = get_memtier_nodemask(memtier); >> + nodes_or(top_tier_mask, top_tier_mask, nmask); >> + } >> + >> + ret = sysfs_emit(buf, "%*pbl\n", nodemask_pr_args(&top_tier_mask)); >> + mutex_unlock(&memory_tier_lock); >> + return ret; >> +} >> +static DEVICE_ATTR_RO(toptier_nodes); >> + >> +static struct attribute *memtier_subsys_attrs[] = { >> + &dev_attr_toptier_nodes.attr, >> + NULL >> +}; >> + >> +static const struct attribute_group memtier_subsys_group = { >> + .attrs = memtier_subsys_attrs, >> +}; >> + >> +static const struct attribute_group *memtier_subsys_groups[] = { >> + &memtier_subsys_group, >> + NULL >> +}; >> + >> static int __init memory_tier_init(void) >> { >> - int node; >> + int ret, node; >> struct memory_tier *memtier; >> >> + ret = subsys_virtual_register(&memory_tier_subsys, memtier_subsys_groups); >> + 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); >> -- >> 2.37.2 >>
