linux-kernel - [PATCH v4 04/31] fs/resctrl: Change how and when events are initialized

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Message-ID: <20250429003359.375508-5-tony.luck@intel.com>
Date: Mon, 28 Apr 2025 17:33:30 -0700
From: Tony Luck <tony.luck@...el.com>
To: Fenghua Yu <fenghuay@...dia.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>,
	Anil Keshavamurthy <anil.s.keshavamurthy@...el.com>,
	Chen Yu <yu.c.chen@...el.com>
Cc: x86@...nel.org,
	linux-kernel@...r.kernel.org,
	patches@...ts.linux.dev,
	Tony Luck <tony.luck@...el.com>
Subject: [PATCH v4 04/31] fs/resctrl: Change how and when events are initialized

Existing code assumes that all monitor events are associated with
the RDT_RESOURCE_L3 resource. Also that all event enumeration is
complete during early resctrl initialization. Neither of these
assumptions remain true for new events.

Each resource must include a list of enabled events that is used
to add appropriately named files when creating mon_data directories
and to for the contents of "info/{resource}_MON/mon_features" file.

Move the building of enabled event lists for each resource from
resctrl_mon_resource_init() to rdt_get_tree() to delay it until
mount of the resctrl file system.

Add a new field to struct mon_evt to record which resource each
event is associated with so that events are added to the correct
resource event list.

Signed-off-by: Tony Luck <tony.luck@...el.com>
---
 fs/resctrl/internal.h |  4 ++++
 fs/resctrl/monitor.c  | 33 ++++++++++++++++++++++-----------
 fs/resctrl/rdtgroup.c |  2 ++
 3 files changed, 28 insertions(+), 11 deletions(-)

diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
index 6029b3285dd3..b69170760316 100644
--- a/fs/resctrl/internal.h
+++ b/fs/resctrl/internal.h
@@ -68,6 +68,7 @@ static inline struct rdt_fs_context *rdt_fc2context(struct fs_context *fc)
 /**
  * struct mon_evt - Entry in the event list of a resource
  * @evtid:		event id
+ * @rid:		index of the resource for this event
  * @name:		name of the event
  * @configurable:	true if the event is configurable
  * @enabled:		true if the event is enabled
@@ -75,6 +76,7 @@ static inline struct rdt_fs_context *rdt_fc2context(struct fs_context *fc)
  */
 struct mon_evt {
 	enum resctrl_event_id	evtid;
+	enum resctrl_res_level	rid;
 	char			*name;
 	bool			configurable;
 	bool			enabled;
@@ -397,6 +399,8 @@ enum resctrl_event_id resctrl_get_mon_event_by_name(char *name);
 
 char *resctrl_mon_event_name(enum resctrl_event_id evt);
 
+void resctrl_init_mon_events(void);
+
 #ifdef CONFIG_RESCTRL_FS_PSEUDO_LOCK
 int rdtgroup_locksetup_enter(struct rdtgroup *rdtgrp);
 
diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
index 625cd328c790..a5a523f73249 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -845,14 +845,17 @@ struct mon_evt mon_event_all[QOS_NUM_EVENTS] = {
 	[QOS_L3_OCCUP_EVENT_ID] = {
 		.name	= "llc_occupancy",
 		.evtid	= QOS_L3_OCCUP_EVENT_ID,
+		.rid	= RDT_RESOURCE_L3,
 	},
 	[QOS_L3_MBM_TOTAL_EVENT_ID] = {
 		.name	= "mbm_total_bytes",
 		.evtid	= QOS_L3_MBM_TOTAL_EVENT_ID,
+		.rid	= RDT_RESOURCE_L3,
 	},
 	[QOS_L3_MBM_LOCAL_EVENT_ID] = {
 		.name	= "mbm_local_bytes",
 		.evtid	= QOS_L3_MBM_LOCAL_EVENT_ID,
+		.rid	= RDT_RESOURCE_L3,
 	},
 };
 
@@ -886,21 +889,31 @@ char *resctrl_mon_event_name(enum resctrl_event_id evt)
 }
 
 /*
- * Initialize the event list for the resource.
+ * Initialize the event list for all mon_capable resources.
  *
- * Note that MBM events are also part of RDT_RESOURCE_L3 resource
- * because as per the SDM the total and local memory bandwidth
- * are enumerated as part of L3 monitoring.
+ * Called on each mount of the resctrl file system when all
+ * events have been enumerated. Only needs to build the per-resource
+ * event lists once.
  */
-static void l3_mon_evt_init(struct rdt_resource *r)
+void resctrl_init_mon_events(void)
 {
 	enum resctrl_event_id evt;
+	struct rdt_resource *r;
+	static bool only_once;
+
+	if (only_once)
+		return;
+	only_once = true;
 
-	INIT_LIST_HEAD(&r->evt_list);
+	for_each_mon_capable_rdt_resource(r)
+		INIT_LIST_HEAD(&r->evt_list);
 
-	for (evt = 0; evt < QOS_NUM_EVENTS; evt++)
-		if (mon_event_all[evt].enabled)
-			list_add_tail(&mon_event_all[evt].list, &r->evt_list);
+	for (evt = 0; evt < QOS_NUM_EVENTS; evt++) {
+		if (!mon_event_all[evt].enabled)
+			continue;
+		r = resctrl_arch_get_resource(mon_event_all[evt].rid);
+		list_add_tail(&mon_event_all[evt].list, &r->evt_list);
+	}
 }
 
 /**
@@ -927,8 +940,6 @@ int resctrl_mon_resource_init(void)
 	if (ret)
 		return ret;
 
-	l3_mon_evt_init(r);
-
 	if (resctrl_arch_is_evt_configurable(QOS_L3_MBM_TOTAL_EVENT_ID)) {
 		mon_event_all[QOS_L3_MBM_TOTAL_EVENT_ID].configurable = true;
 		resctrl_file_fflags_init("mbm_total_bytes_config",
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index c06752dfcb7c..e66dc041be5f 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -2591,6 +2591,8 @@ static int rdt_get_tree(struct fs_context *fc)
 		goto out;
 	}
 
+	resctrl_init_mon_events();
+
 	ret = rdtgroup_setup_root(ctx);
 	if (ret)
 		goto out;
-- 
2.48.1