[PATCH v3 01/11] mm/mempolicy: implement the sysfs-based weighted_interleave interface

Gregory Price
2023-12-13T22:41:28Z

From: Rakie Kim <rakie.kim@sk.com>

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

Signed-off-by: Rakie Kim <rakie.kim@sk.com>
Signed-off-by: Honggyu Kim <honggyu.kim@sk.com>
Co-developed-by: Gregory Price <gregory.price@memverge.com>
Signed-off-by: Gregory Price <gregory.price@memverge.com>
Co-developed-by: Hyeongtak Ji <hyeongtak.ji@sk.com>
Signed-off-by: Hyeongtak Ji <hyeongtak.ji@sk.com>
---
.../ABI/testing/sysfs-kernel-mm-mempolicy | 4 +
...fs-kernel-mm-mempolicy-weighted-interleave | 22 +++
mm/mempolicy.c | 143 ++++++++++++++++++
3 files changed, 169 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 <linux-mm@kvack.org>
+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..aa27fdf08c19
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-kernel-mm-mempolicy-weighted-interleave
@@ -0,0 +1,22 @@
+What: /sys/kernel/mm/mempolicy/weighted_interleave/
+Date: December 2023
+Contact: Linux memory management mailing list <linux-mm@kvack.org>
+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 <linux-mm@kvack.org>
+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.
+
+ Writing an empty string resets the weight value to 1.
+
+ Minimum weight: 1
+ Maximum weight: 255
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 10a590ee1c89..5310021181ab 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -131,6 +131,8 @@ static struct mempolicy default_policy = {

static struct mempolicy preferred_node_policy[MAX_NUMNODES];

+static char iw_table[MAX_NUMNODES];
+
/**
* numa_nearest_node - Find nearest node by state
* @node: Node id to start the search
@@ -3067,3 +3069,144 @@ void mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol)
p += scnprintf(p, buffer + maxlen - p, ":%*pbl",
nodemask_pr_args(&nodes));
}
+
+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;
+
+ node_attr = container_of(attr, struct iw_node_attr, kobj_attr);
+ return sysfs_emit(buf, "%d\n", iw_table[node_attr->nid]);
+}
+
+static ssize_t node_store(struct kobject *kobj, struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct iw_node_attr *node_attr;
+ unsigned char weight = 0;
+
+ node_attr = container_of(attr, struct iw_node_attr, kobj_attr);
+ /* If no input, set default weight to 1 */
+ if (count == 0 || sysfs_streq(buf, ""))
+ weight = 1;
+ else if (kstrtou8(buf, 0, &weight) || !weight)
+ return -EINVAL;
+
+ iw_table[node_attr->nid] = weight;
+ 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_mempolicy_release(struct kobject *mempolicy_kobj)
+{
+ int i;
+
+ for (i = 0; i < MAX_NUMNODES; i++)
+ sysfs_wi_node_release(node_attrs[i], mempolicy_kobj);
+ kobject_put(mempolicy_kobj);
+}
+
+static const struct kobj_type mempolicy_ktype = {
+ .sysfs_ops = &kobj_sysfs_ops,
+ .release = sysfs_mempolicy_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->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, &mempolicy_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 int __init mempolicy_sysfs_init(void)
+{
+ int err;
+ struct kobject *root_kobj;
+
+ memset(&iw_table, 1, sizeof(iw_table));
+
+ root_kobj = kobject_create_and_add("mempolicy", mm_kobj);
+ if (!root_kobj) {
+ pr_err("failed to add mempolicy kobject to the system\n");
+ return -ENOMEM;
+ }
+
+ err = add_weighted_interleave_group(root_kobj);
+
+ if (err)
+ kobject_put(root_kobj);
+ return err;
+
+}
+late_initcall(mempolicy_sysfs_init);
--
2.39.1