[PATCH RFC v2 03/19] resctrl: name node-scoped monitor domains mon_NODE_<id>

[Fenghua Yu <fenghuay@nvidia.com>]

Monitor domain directories under mon_data are named mon_<name>_<id>,
using the resource name as the label. For memory bandwidth monitoring on
a memory-side MSC the domain id is a NUMA node id, so labelling those
directories with the resource name ("MB") is misleading about what the
id means.

Add the RESCTRL_NODE monitor scope and a mon_domain_name() helper that
returns "NODE" for node-scoped resources (and the resource name for all
other scopes), then use it when building and removing monitor domain
directories. Node-scoped monitor domains are now named mon_NODE_<id>,
making it clear the id is a NUMA node id. L3 and telemetry naming
(mon_L3_<id>, mon_PERF_PKG_<id>) is unchanged.

Signed-off-by: Fenghua Yu <fenghuay@nvidia.com>
---
 fs/resctrl/rdtgroup.c   | 25 +++++++++++++++++++++----
 include/linux/resctrl.h |  1 +
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index a0635888a0a0..264666e54852 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -3967,6 +3967,20 @@ static void mon_rmdir_one_subdir(struct kernfs_node *pkn, char *name, char *subn
 		kernfs_remove_by_name(kn, subname);
 }
 
+/*
+ * Label used in the mon_<label>_<id> monitor domain directory names. Node
+ * scoped monitoring (for example MB on a memory MSC) uses "NODE" so the id
+ * is understood as a NUMA node id; other scopes keep the resource name
+ * (L3 -> "L3", telemetry -> "PERF_PKG").
+ */
+static const char *mon_domain_name(struct rdt_resource *r)
+{
+	if (r->mon_scope == RESCTRL_NODE)
+		return "NODE";
+
+	return r->name;
+}
+
 /*
  * Remove files and directories for one SNC node. If it is the last node
  * sharing an L3 cache, then remove the upper level directory containing
@@ -4010,7 +4024,7 @@ static void rmdir_mondata_subdir_allrdtgrp(struct rdt_resource *r,
 		return;
 	}
 
-	sprintf(name, "mon_%s_%02d", r->name, hdr->id);
+	sprintf(name, "mon_%s_%02d", mon_domain_name(r), hdr->id);
 	list_for_each_entry(prgrp, &rdt_all_groups, rdtgroup_list) {
 		kernfs_remove_by_name(prgrp->mon.mon_data_kn, name);
 
@@ -4114,7 +4128,7 @@ static int mkdir_mondata_subdir(struct kernfs_node *parent_kn,
 	if (r->rid == RDT_RESOURCE_L3 && r->mon_scope == RESCTRL_L3_NODE)
 		return mkdir_mondata_subdir_snc(parent_kn, hdr, r, prgrp);
 
-	sprintf(name, "mon_%s_%02d", r->name, hdr->id);
+	sprintf(name, "mon_%s_%02d", mon_domain_name(r), hdr->id);
 	kn = _mkdir_mondata_subdir(parent_kn, name, hdr, r, prgrp, hdr->id);
 	if (IS_ERR(kn))
 		return PTR_ERR(kn);
@@ -4169,8 +4183,11 @@ static int mkdir_mondata_subdir_alldom(struct kernfs_node *parent_kn,
  * This creates a directory mon_data which contains the monitored data.
  *
  * mon_data has one directory for each domain which are named
- * in the format mon_<domain_name>_<domain_id>. For ex: A mon_data
- * with L3 domain looks as below:
+ * in the format mon_<domain_name>_<domain_id>. The domain name is the
+ * resource name for cache and telemetry scopes (for example "L3") and
+ * "NODE" for node scoped monitoring (for example MB on a memory MSC,
+ * where <domain_id> is a NUMA node id). For ex: A mon_data with L3 domain
+ * looks as below:
  * ./mon_data:
  * mon_L3_00
  * mon_L3_01
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 54fec07bd173..f2c3621b006e 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -349,6 +349,7 @@ enum resctrl_scope {
 	RESCTRL_L3_CACHE = 3,
 	RESCTRL_L3_NODE,
 	RESCTRL_PACKAGE,
+	RESCTRL_NODE,
 };
 
 /**
-- 
2.53.0