linux-kernel - [PATCH v18 12/17] x86/resctrl: Create Sub-NUMA (SNC) monitor files

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Date: Wed, 15 May 2024 15:23:20 -0700
From: Tony Luck <tony.luck@...el.com>
To: Fenghua Yu <fenghua.yu@...el.com>,
	Reinette Chatre <reinette.chatre@...el.com>,
	Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>,
	Peter Newman <peternewman@...gle.com>,
	James Morse <james.morse@....com>,
	Babu Moger <babu.moger@....com>,
	Drew Fustini <dfustini@...libre.com>,
	Dave Martin <Dave.Martin@....com>
Cc: x86@...nel.org,
	linux-kernel@...r.kernel.org,
	patches@...ts.linux.dev,
	Tony Luck <tony.luck@...el.com>
Subject: [PATCH v18 12/17] x86/resctrl: Create Sub-NUMA (SNC) monitor files

When SNC mode is enabled, create subdirectories and file to monitor
at the SNC node granularity. Monitor files at the L3 granularity are
tagged with a "sum" attribute to indicate that all SNC nodes sharing
an L3 cache should be read and summed to provide the result to the
user.

Note that the "domid" field for files that must sum across SNC domains
has the L3 cache instance id, while non-summing files use the domain id.

Also the "sum" files do not need to make a call to mon_event_read() to
initialize the MBM counters. This will be handled by initializing the
individual SNC nodes that share the L3.

Signed-off-by: Tony Luck <tony.luck@...el.com>
---
 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 53 ++++++++++++++++++--------
 1 file changed, 38 insertions(+), 15 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 7a6c40aefdcc..f0f468babdea 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -3026,7 +3026,8 @@ static void rmdir_mondata_subdir_allrdtgrp(struct rdt_resource *r,
 }
 
 static int mon_add_all_files(struct kernfs_node *kn, struct rdt_mon_domain *d,
-			     struct rdt_resource *r, struct rdtgroup *prgrp)
+			     struct rdt_resource *r, struct rdtgroup *prgrp,
+			     bool do_sum)
 {
 	union mon_data_bits priv;
 	struct mon_evt *mevt;
@@ -3037,15 +3038,18 @@ static int mon_add_all_files(struct kernfs_node *kn, struct rdt_mon_domain *d,
 		return -EPERM;
 
 	priv.u.rid = r->rid;
-	priv.u.domid = d->hdr.id;
+	priv.u.domid = do_sum ? d->display_id : d->hdr.id;
+	priv.u.sum = do_sum;
 	list_for_each_entry(mevt, &r->evt_list, list) {
 		priv.u.evtid = mevt->evtid;
 		ret = mon_addfile(kn, mevt->name, priv.priv);
 		if (ret)
 			return ret;
 
-		if (is_mbm_event(mevt->evtid))
+		if (!do_sum && is_mbm_event(mevt->evtid)) {
+			rr.sumdomains = 0;
 			mon_event_read(&rr, r, d, prgrp, mevt->evtid, true);
+		}
 	}
 
 	return 0;
@@ -3055,23 +3059,42 @@ static int mkdir_mondata_subdir(struct kernfs_node *parent_kn,
 				struct rdt_mon_domain *d,
 				struct rdt_resource *r, struct rdtgroup *prgrp)
 {
-	struct kernfs_node *kn;
+	struct kernfs_node *kn, *ckn;
 	char name[32];
+	bool do_sum;
 	int ret;
 
-	sprintf(name, "mon_%s_%02d", r->name, d->hdr.id);
-	/* create the directory */
-	kn = kernfs_create_dir(parent_kn, name, parent_kn->mode, prgrp);
-	if (IS_ERR(kn))
-		return PTR_ERR(kn);
+	do_sum = r->mon_scope != r->mon_display_scope;
+	sprintf(name, "mon_%s_%02d", r->name, d->display_id);
+	kn = kernfs_find_and_get_ns(parent_kn, name, NULL);
+	if (!kn) {
+		/* create the directory */
+		kn = kernfs_create_dir(parent_kn, name, parent_kn->mode, prgrp);
+		if (IS_ERR(kn))
+			return PTR_ERR(kn);
 
-	ret = rdtgroup_kn_set_ugid(kn);
-	if (ret)
-		goto out_destroy;
+		ret = rdtgroup_kn_set_ugid(kn);
+		if (ret)
+			goto out_destroy;
+		ret = mon_add_all_files(kn, d, r, prgrp, do_sum);
+		if (ret)
+			goto out_destroy;
+	}
 
-	ret = mon_add_all_files(kn, d, r, prgrp);
-	if (ret)
-		goto out_destroy;
+	if (do_sum) {
+		sprintf(name, "mon_sub_%s_%02d", r->name, d->hdr.id);
+		ckn = kernfs_create_dir(kn, name, parent_kn->mode, prgrp);
+		if (IS_ERR(ckn))
+			goto out_destroy;
+
+		ret = rdtgroup_kn_set_ugid(ckn);
+		if (ret)
+			goto out_destroy;
+
+		ret = mon_add_all_files(ckn, d, r, prgrp, false);
+		if (ret)
+			goto out_destroy;
+	}
 
 	kernfs_activate(kn);
 	return 0;
-- 
2.44.0