[PATCH v3 11/26] fs/resctrl: Add support for additional monitor event display formats

Tony Luck
2025-04-07T23:40:53Z

Add a type field to both the mon_evt and mon_data structures.

Legacy monitor events are still all displayed as an unsigned decimal
64-bit integer.

Add an additional format of fixed-point with 18 binary places displayed
as a floating point value with six decimal places.

Signed-off-by: Tony Luck <tony.luck@intel.com>
---
include/linux/resctrl_types.h | 8 ++++++++
fs/resctrl/internal.h | 4 ++++
fs/resctrl/ctrlmondata.c | 23 ++++++++++++++++++++++-
fs/resctrl/monitor.c | 3 +++
fs/resctrl/rdtgroup.c | 1 +
5 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/include/linux/resctrl_types.h b/include/linux/resctrl_types.h
index 898068a99ef7..fbd4b55c41aa 100644
--- a/include/linux/resctrl_types.h
+++ b/include/linux/resctrl_types.h
@@ -58,6 +58,14 @@ enum resctrl_event_id {
#define QOS_NUM_MBM_EVENTS (QOS_L3_MBM_LOCAL_EVENT_ID - QOS_L3_MBM_TOTAL_EVENT_ID + 1)
#define MBM_EVENT_IDX(evt) ((evt) - QOS_L3_MBM_TOTAL_EVENT_ID)

+/*
+ * Event value display types
+ */
+enum resctrl_event_type {
+ EVT_TYPE_U64,
+ EVT_TYPE_U46_18,
+};
+
static inline bool resctrl_is_mbm_event(int e)
{
return (e >= QOS_L3_MBM_TOTAL_EVENT_ID &&
diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
index 74a77794364d..4a840e683e96 100644
--- a/fs/resctrl/internal.h
+++ b/fs/resctrl/internal.h
@@ -71,6 +71,7 @@ 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
* @name: name of the event
+ * @type: format for display to user
* @configurable: true if the event is configurable
* @any_cpu: true if this event can be read from any CPU
* @list: entry in &rdt_resource->evt_list
@@ -79,6 +80,7 @@ struct mon_evt {
enum resctrl_event_id evtid;
enum resctrl_res_level rid;
char *name;
+ enum resctrl_event_type type;
bool configurable;
bool any_cpu;
struct list_head list;
@@ -89,6 +91,7 @@ struct mon_evt {
* @list: List of all allocated structures.
* @rid: Resource id associated with the event file.
* @evtid: Event id associated with the event file.
+ * @type: Format for display to user
* @sum: Set when event must be summed across multiple
* domains.
* @domid: When @sum is zero this is the domain to which
@@ -104,6 +107,7 @@ struct mon_data {
struct list_head list;
unsigned int rid;
enum resctrl_event_id evtid;
+ enum resctrl_event_type type;
unsigned int sum;
unsigned int domid;
bool any_cpu;
diff --git a/fs/resctrl/ctrlmondata.c b/fs/resctrl/ctrlmondata.c
index cd77960657f0..5ea8113c96ac 100644
--- a/fs/resctrl/ctrlmondata.c
+++ b/fs/resctrl/ctrlmondata.c
@@ -562,6 +562,27 @@ void mon_event_read(struct rmid_read *rr, struct rdt_resource *r,
resctrl_arch_mon_ctx_free(r, evtid, rr->arch_mon_ctx);
}

+#define NUM_FRAC_BITS 18
+#define FRAC_MASK GENMASK(NUM_FRAC_BITS - 1, 0)
+
+static void show_value(struct seq_file *m, enum resctrl_event_type type, u64 val)
+{
+ u64 frac;
+
+ switch (type) {
+ case EVT_TYPE_U64:
+ seq_printf(m, "%llu\n", val);
+ break;
+ case EVT_TYPE_U46_18:
+ frac = val & FRAC_MASK;
+ frac = frac * 1000000;
+ frac += 1ul << (NUM_FRAC_BITS - 1);
+ frac >>= NUM_FRAC_BITS;
+ seq_printf(m, "%llu.%06llu\n", val >> NUM_FRAC_BITS, frac);
+ break;
+ }
+}
+
int rdtgroup_mondata_show(struct seq_file *m, void *arg)
{
struct kernfs_open_file *of = m->private;
@@ -633,7 +654,7 @@ int rdtgroup_mondata_show(struct seq_file *m, void *arg)
else if (rr.err == -EINVAL)
seq_puts(m, "Unavailable\n");
else
- seq_printf(m, "%llu\n", rr.val);
+ show_value(m, md->type, rr.val);

out:
rdtgroup_kn_unlock(of->kn);
diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
index 1cf0b085e07a..1efad57d1d85 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -847,16 +847,19 @@ static struct mon_evt all_events[QOS_NUM_EVENTS] = {
.name = "llc_occupancy",
.evtid = QOS_L3_OCCUP_EVENT_ID,
.rid = RDT_RESOURCE_L3,
+ .type = EVT_TYPE_U64,
},
[QOS_L3_MBM_TOTAL_EVENT_ID] = {
.name = "mbm_total_bytes",
.evtid = QOS_L3_MBM_TOTAL_EVENT_ID,
.rid = RDT_RESOURCE_L3,
+ .type = EVT_TYPE_U64,
},
[QOS_L3_MBM_LOCAL_EVENT_ID] = {
.name = "mbm_local_bytes",
.evtid = QOS_L3_MBM_LOCAL_EVENT_ID,
.rid = RDT_RESOURCE_L3,
+ .type = EVT_TYPE_U64,
},
};

diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 97c2ba8af930..bd41f7a0f416 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -2927,6 +2927,7 @@ static struct mon_data *mon_get_kn_priv(int rid, int domid, struct mon_evt *mevt
priv->sum = do_sum;
priv->evtid = mevt->evtid;
priv->any_cpu = mevt->any_cpu;
+ priv->type = mevt->type;
list_add_tail(&priv->list, &kn_priv_list);

return priv;
--
2.48.1