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[173.79.56.208]) by smtp.gmail.com with ESMTPSA id ci24-20020a05690c0a9800b005f93cc31ff0sm1635518ywb.72.2024.01.12.13.08.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 12 Jan 2024 13:08:39 -0800 (PST) From: Gregory Price X-Google-Original-From: Gregory Price To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, corbet@lwn.net, akpm@linux-foundation.org, gregory.price@memverge.com, honggyu.kim@sk.com, rakie.kim@sk.com, hyeongtak.ji@sk.com, mhocko@kernel.org, ying.huang@intel.com, vtavarespetr@micron.com, jgroves@micron.com, ravis.opensrc@micron.com, sthanneeru@micron.com, emirakhur@micron.com, Hasan.Maruf@amd.com, seungjun.ha@samsung.com, hannes@cmpxchg.org, dan.j.williams@intel.com Subject: [PATCH 1/3] mm/mempolicy: implement the sysfs-based weighted_interleave interface Date: Fri, 12 Jan 2024 16:08:32 -0500 Message-Id: <20240112210834.8035-2-gregory.price@memverge.com> X-Mailer: git-send-email 2.39.1 In-Reply-To: <20240112210834.8035-1-gregory.price@memverge.com> References: <20240112210834.8035-1-gregory.price@memverge.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Rakie Kim This patch provides a way to set interleave weight information under sysfs at /sys/kernel/mm/mempolicy/weighted_interleave/nodeN The sysfs structure is designed as follows. $ tree /sys/kernel/mm/mempolicy/ /sys/kernel/mm/mempolicy/ [1] └── weighted_interleave [2] ├── node0 [3] └── node1 Each file above can be explained as follows. [1] mm/mempolicy: configuration interface for mempolicy subsystem [2] weighted_interleave/: config interface for weighted interleave policy [3] weighted_interleave/nodeN: weight for nodeN Internally, there is a secondary table `default_iw_table`, which holds kernel-internal default interleave weights for each possible node. If the value for a node is set to `0`, the default value will be used. If sysfs is disabled in the config, interleave weights will default to use `default_iw_table`. Suggested-by: Huang Ying Signed-off-by: Rakie Kim Signed-off-by: Honggyu Kim Co-developed-by: Gregory Price Signed-off-by: Gregory Price Co-developed-by: Hyeongtak Ji Signed-off-by: Hyeongtak Ji --- .../ABI/testing/sysfs-kernel-mm-mempolicy | 4 + ...fs-kernel-mm-mempolicy-weighted-interleave | 26 ++ mm/mempolicy.c | 251 ++++++++++++++++++ 3 files changed, 281 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-kernel-mm-mempolicy create mode 100644 Documentation/ABI/testing/sysfs-kernel-mm-mempolicy-weighted-interleave diff --git a/Documentation/ABI/testing/sysfs-kernel-mm-mempolicy b/Documentation/ABI/testing/sysfs-kernel-mm-mempolicy new file mode 100644 index 000000000000..2dcf24f4384a --- /dev/null +++ b/Documentation/ABI/testing/sysfs-kernel-mm-mempolicy @@ -0,0 +1,4 @@ +What: /sys/kernel/mm/mempolicy/ +Date: December 2023 +Contact: Linux memory management mailing list +Description: Interface for Mempolicy diff --git a/Documentation/ABI/testing/sysfs-kernel-mm-mempolicy-weighted-interleave b/Documentation/ABI/testing/sysfs-kernel-mm-mempolicy-weighted-interleave new file mode 100644 index 000000000000..e6a38139bf0f --- /dev/null +++ b/Documentation/ABI/testing/sysfs-kernel-mm-mempolicy-weighted-interleave @@ -0,0 +1,26 @@ +What: /sys/kernel/mm/mempolicy/weighted_interleave/ +Date: December 2023 +Contact: Linux memory management mailing list +Description: Configuration Interface for the Weighted Interleave policy + +What: /sys/kernel/mm/mempolicy/weighted_interleave/nodeN +Date: December 2023 +Contact: Linux memory management mailing list +Description: Weight configuration interface for nodeN + + The interleave weight for a memory node (N). These weights are + utilized by processes which have set their mempolicy to + MPOL_WEIGHTED_INTERLEAVE and have opted into global weights by + omitting a task-local weight array. + + These weights only affect new allocations, and changes at runtime + will not cause migrations on already allocated pages. + + The minimum weight for a node is always 1. + + Minimum weight: 1 + Maximum weight: 255 + + Writing an empty string or `0` will reset the weight to the + system default. The system default may be set by the kernel + or drivers at boot or during hotplug events. diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 10a590ee1c89..5da4fd79fd18 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -131,6 +131,30 @@ static struct mempolicy default_policy = { static struct mempolicy preferred_node_policy[MAX_NUMNODES]; +struct iw_table { + struct rcu_head rcu; + u8 weights[MAX_NUMNODES]; +}; +/* + * default_iw_table is the kernel-internal default value interleave + * weight table. It is to be set by driver code capable of reading + * HMAT/CDAT information, and to provide mempolicy a sane set of + * default weight values for WEIGHTED_INTERLEAVE mode. + * + * By default, prior to HMAT/CDAT information being consumed, the + * default weight of all nodes is 1. The default weight of any + * node can only be in the range 1-255. A 0-weight is not allowed. + */ +static struct iw_table default_iw_table; +/* + * iw_table is the sysfs-set interleave weight table, a value of 0 + * denotes that the default_iw_table value should be used. + * + * iw_table is RCU protected + */ +static struct iw_table __rcu *iw_table; +static DEFINE_MUTEX(iw_table_mtx); + /** * numa_nearest_node - Find nearest node by state * @node: Node id to start the search @@ -3067,3 +3091,230 @@ void mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol) p += scnprintf(p, buffer + maxlen - p, ":%*pbl", nodemask_pr_args(&nodes)); } + +#ifdef CONFIG_SYSFS +struct iw_node_attr { + struct kobj_attribute kobj_attr; + int nid; +}; + +static ssize_t node_show(struct kobject *kobj, struct kobj_attribute *attr, + char *buf) +{ + struct iw_node_attr *node_attr; + u8 weight; + struct iw_table __rcu *table; + + node_attr = container_of(attr, struct iw_node_attr, kobj_attr); + + rcu_read_lock(); + table = rcu_dereference(iw_table); + weight = table->weights[node_attr->nid]; + rcu_read_unlock(); + + return sysfs_emit(buf, "%d\n", weight); +} + +static ssize_t node_store(struct kobject *kobj, struct kobj_attribute *attr, + const char *buf, size_t count) +{ + struct iw_node_attr *node_attr; + struct iw_table __rcu *new; + struct iw_table __rcu *old; + u8 weight = 0; + + node_attr = container_of(attr, struct iw_node_attr, kobj_attr); + if (count == 0 || sysfs_streq(buf, "")) + weight = 0; + else if (kstrtou8(buf, 0, &weight)) + return -EINVAL; + + new = kmalloc(sizeof(*new), GFP_KERNEL); + if (!new) + return -ENOMEM; + + mutex_lock(&iw_table_mtx); + old = rcu_dereference_protected(iw_table, + lockdep_is_held(&iw_table_mtx)); + /* If value is 0, revert to default weight */ + weight = weight ? weight : default_iw_table.weights[node_attr->nid]; + memcpy(&new->weights, &old->weights, sizeof(new->weights)); + new->weights[node_attr->nid] = weight; + rcu_assign_pointer(iw_table, new); + mutex_unlock(&iw_table_mtx); + kfree_rcu(old, rcu); + return count; +} + +static struct iw_node_attr *node_attrs[MAX_NUMNODES]; + +static void sysfs_wi_node_release(struct iw_node_attr *node_attr, + struct kobject *parent) +{ + if (!node_attr) + return; + sysfs_remove_file(parent, &node_attr->kobj_attr.attr); + kfree(node_attr->kobj_attr.attr.name); + kfree(node_attr); +} + +static void sysfs_wi_release(struct kobject *wi_kobj) +{ + int i; + + for (i = 0; i < MAX_NUMNODES; i++) + sysfs_wi_node_release(node_attrs[i], wi_kobj); + kobject_put(wi_kobj); +} + +static const struct kobj_type wi_ktype = { + .sysfs_ops = &kobj_sysfs_ops, + .release = sysfs_wi_release, +}; + +static int add_weight_node(int nid, struct kobject *wi_kobj) +{ + struct iw_node_attr *node_attr; + char *name; + + node_attr = kzalloc(sizeof(*node_attr), GFP_KERNEL); + if (!node_attr) + return -ENOMEM; + + name = kasprintf(GFP_KERNEL, "node%d", nid); + if (!name) { + kfree(node_attr); + return -ENOMEM; + } + + sysfs_attr_init(&node_attr->kobj_attr.attr); + node_attr->kobj_attr.attr.name = name; + node_attr->kobj_attr.attr.mode = 0644; + node_attr->kobj_attr.show = node_show; + node_attr->kobj_attr.store = node_store; + node_attr->nid = nid; + + if (sysfs_create_file(wi_kobj, &node_attr->kobj_attr.attr)) { + kfree(node_attr->kobj_attr.attr.name); + kfree(node_attr); + pr_err("failed to add attribute to weighted_interleave\n"); + return -ENOMEM; + } + + node_attrs[nid] = node_attr; + return 0; +} + +static int add_weighted_interleave_group(struct kobject *root_kobj) +{ + struct kobject *wi_kobj; + int nid, err; + + wi_kobj = kzalloc(sizeof(struct kobject), GFP_KERNEL); + if (!wi_kobj) + return -ENOMEM; + + err = kobject_init_and_add(wi_kobj, &wi_ktype, root_kobj, + "weighted_interleave"); + if (err) { + kfree(wi_kobj); + return err; + } + + memset(node_attrs, 0, sizeof(node_attrs)); + for_each_node_state(nid, N_POSSIBLE) { + err = add_weight_node(nid, wi_kobj); + if (err) { + pr_err("failed to add sysfs [node%d]\n", nid); + break; + } + } + if (err) + kobject_put(wi_kobj); + return 0; +} + +static void mempolicy_kobj_release(struct kobject *kobj) +{ + if (iw_table != &default_iw_table) + kfree(iw_table); + kfree(kobj); +} + +static const struct kobj_type mempolicy_ktype = { + .release = mempolicy_kobj_release +}; + +static struct kobject *mempolicy_kobj; +static int __init mempolicy_sysfs_init(void) +{ + int err; + struct kobject *mempolicy_kobj; + struct iw_table __rcu *table = NULL; + + /* + * If sysfs setup fails, utilize the default weight table + * This at least allows mempolicy to continue functioning safely. + */ + memset(&default_iw_table.weights, 1, MAX_NUMNODES); + iw_table = &default_iw_table; + + table = kzalloc(sizeof(struct iw_table), GFP_KERNEL); + if (!table) + return -ENOMEM; + + memcpy(&table->weights, default_iw_table.weights, + sizeof(table->weights)); + + mempolicy_kobj = kzalloc(sizeof(*mempolicy_kobj), GFP_KERNEL); + if (!mempolicy_kobj) { + kfree(table); + pr_err("failed to add mempolicy kobject to the system\n"); + return -ENOMEM; + } + err = kobject_init_and_add(mempolicy_kobj, &mempolicy_ktype, mm_kobj, + "mempolicy"); + if (err) { + kfree(table); + kfree(mempolicy_kobj); + return err; + } + + err = add_weighted_interleave_group(mempolicy_kobj); + + if (err) { + kobject_put(mempolicy_kobj); + return err; + } + + iw_table = table; + return err; +} + +static void __exit mempolicy_exit(void) +{ + if (mempolicy_kobj) + kobject_put(mempolicy_kobj); +} + +#else +static int __init mempolicy_sysfs_init(void) +{ + /* + * if sysfs is not enabled MPOL_WEIGHTED_INTERLEAVE defaults to + * MPOL_INTERLEAVE behavior, but is still defined separately to + * allow task-local weighted interleave and system-defaults to + * operate as intended. + * + * In this scenario iw_table cannot (presently) change, so + * there's no need to set up RCU / cleanup code. + */ + memset(&default_iw_table.weights, 1, sizeof(default_iw_table)); + iw_table = default_iw_table; + return 0; +} + +static void __exit mempolicy_exit(void) { } +#endif /* CONFIG_SYSFS */ +late_initcall(mempolicy_sysfs_init); +module_exit(mempolicy_exit);