On Wed, 06 Dec 2023, Gregory Price wrote:
Signed-off-by: Rakie Kim <rakie.kim@xxxxxx>
Signed-off-by: Honggyu Kim <honggyu.kim@xxxxxx>
Co-developed-by: Gregory Price <gregory.price@xxxxxxxxxxxx>
Signed-off-by: Gregory Price <gregory.price@xxxxxxxxxxxx>
Co-developed-by: Hyeongtak Ji <hyeongtak.ji@xxxxxx>
Signed-off-by: Hyeongtak Ji <hyeongtak.ji@xxxxxx>
fyi Rakie's tag needs to be last, per the From.
...
+What: /sys/kernel/mm/mempolicy/weighted_interleave/
+Date: December 2023
+Contact: Linux memory management mailing list <linux-mm@xxxxxxxxx>
+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@xxxxxxxxx>
+Description: Configuration interface for accesses initiated from nodeN
+
+ The directory to configure access initiator weights for nodeN.
+
+ Possible numa nodes which have not been marked as a CPU node
+ at boot will not have a nodeN directory made for them at boot.
This could be better rephrased without the negation. ie:
"Only numa nodes with CPUs (compute) will have a nodeN directory."
+ Hotplug for CPU nodes is not supported.
Can this even happen? Hot-adding a previously offlined CPU won't change/add a
new numa node. So just rm the line altogether?
+
+What: /sys/kernel/mm/mempolicy/weighted_interleave/nodeN/nodeM
+ /sys/kernel/mm/mempolicy/weighted_interleave/nodeN/nodeM/weight
+Date: December 2023
+Contact: Linux memory management mailing list <linux-mm@xxxxxxxxx>
+Description: Configuration interface for target nodes accessed from nodeNN
+
+ The interleave weight for a memory node (M) from initiating
+ node (N). These weights are utilized by processes which have set
+ the 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.
+
+ If the weight of 0 is desired, the appropriate way to do this is
+ by removing the node from the weighted interleave nodemask.
+
+ Minimum weight: 1
+ Maximum weight: 255
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 10a590ee1c89..ce332b5e7a03 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -131,6 +131,11 @@ static struct mempolicy default_policy = {
static struct mempolicy preferred_node_policy[MAX_NUMNODES];
+struct interleave_weight_table {
+ unsigned char weights[MAX_NUMNODES];
+};
+static struct interleave_weight_table *iw_table;
+
/**
* numa_nearest_node - Find nearest node by state
* @node: Node id to start the search
@@ -3067,3 +3072,224 @@ 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_info {
+ struct kobject kobj;
+ int src;
+ int dst;
+};
+
+static ssize_t node_weight_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ struct iw_node_info *node_info = container_of(kobj, struct iw_node_info,
+ kobj);
+ return sysfs_emit(buf, "%d\n",
+ iw_table[node_info->src].weights[node_info->dst]);
+}
+
+static ssize_t node_weight_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ unsigned char weight = 0;
+ struct iw_node_info *node_info = NULL;
+
+ node_info = container_of(kobj, struct iw_node_info, kobj);
+
+ if (kstrtou8(buf, 0, &weight) || !weight)
+ return -EINVAL;
+
+ iw_table[node_info->src].weights[node_info->dst] = weight;
+
+ return count;
+}
iw_table will need some (basic) form of serialization.
...
+static int __init mempolicy_sysfs_init(void)
+{
+ int err, nid;
+ int cpunodes = 0;
+ struct kobject *root_kobj;
+
+ for_each_node_state(nid, N_CPU)
+ cpunodes += 1;
+ iw_table = kmalloc_array(cpunodes, sizeof(*iw_table), GFP_KERNEL);
+ if (!iw_table) {
+ pr_err("failed to create interleave weight table\n");
+ err = -ENOMEM;
+ goto fail_obj;
No ref here yet, just return -ENOMEM.
+ }
+ memset(iw_table, 1, cpunodes * sizeof(*iw_table));
+
+ root_kobj = kzalloc(sizeof(struct kobject), GFP_KERNEL);
+ if (!root_kobj)
+ return -ENOMEM;
+
+ kobject_init(root_kobj, &mempolicy_kobj_ktype);
+ err = kobject_add(root_kobj, mm_kobj, "mempolicy");
+ if (err) {
+ pr_err("failed to add kobject to the system\n");
+ goto fail_obj;
+ }
+
+ err = sysfs_create_group(root_kobj, &mempolicy_attr_group);
+ if (err) {
+ pr_err("failed to register mempolicy group\n");
+ goto fail_obj;
+ }
+
+ err = add_weighted_interleave_group(root_kobj);
+fail_obj:
+ if (err)
+ kobject_put(root_kobj);
+ return err;
+
+}
+late_initcall(mempolicy_sysfs_init);
--
2.39.1
