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arm_mpam: resctrl: Add support for csu counters

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resctrl exposes a counter via a file named llc_occupancy. This isn't really
a counter as its value goes up and down, this is a snapshot of the cache
storage usage monitor.

Add some picking code which will only find an L3. The resctrl counter
file is called llc_occupancy but we don't check it is the last one as
it is already identified as L3.

Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-by: Zeng Heng <zengheng4@huawei.com>
Tested-by: Punit Agrawal <punit.agrawal@oss.qualcomm.com>
Tested-by: Gavin Shan <gshan@redhat.com>
Tested-by: Jesse Chick <jessechick@os.amperecomputing.com>
Reviewed-by: Zeng Heng <zengheng4@huawei.com>
Reviewed-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Co-developed-by: Dave Martin <dave.martin@arm.com>
Signed-off-by: Dave Martin <dave.martin@arm.com>
Co-developed-by: Ben Horgan <ben.horgan@arm.com>
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
This commit is contained in:
James Morse
2026-03-13 14:46:05 +00:00
parent 264c285999
commit 1458c4f053
1 changed files with 83 additions and 0 deletions
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83
drivers/resctrl/mpam_resctrl.c
View File

@@ -311,6 +311,28 @@ static bool class_has_usable_mba(struct mpam_props *cprops)
return mba_class_use_mbw_max(cprops);
}
static bool cache_has_usable_csu(struct mpam_class *class)
{
struct mpam_props *cprops;
if (!class)
return false;
cprops = &class->props;
if (!mpam_has_feature(mpam_feat_msmon_csu, cprops))
return false;
/*
* CSU counters settle on the value, so we can get away with
* having only one.
*/
if (!cprops->num_csu_mon)
return false;
return true;
}
/*
* Calculate the worst-case percentage change from each implemented step
* in the control.
@@ -630,6 +652,64 @@ static void mpam_resctrl_pick_mba(void)
}
}
static void counter_update_class(enum resctrl_event_id evt_id,
struct mpam_class *class)
{
struct mpam_class *existing_class = mpam_resctrl_counters[evt_id].class;
if (existing_class) {
if (class->level == 3) {
pr_debug("Existing class is L3 - L3 wins\n");
return;
}
if (existing_class->level < class->level) {
pr_debug("Existing class is closer to L3, %u versus %u - closer is better\n",
existing_class->level, class->level);
return;
}
}
mpam_resctrl_counters[evt_id].class = class;
}
static void mpam_resctrl_pick_counters(void)
{
struct mpam_class *class;
lockdep_assert_cpus_held();
guard(srcu)(&mpam_srcu);
list_for_each_entry_srcu(class, &mpam_classes, classes_list,
srcu_read_lock_held(&mpam_srcu)) {
/* The name of the resource is L3... */
if (class->type == MPAM_CLASS_CACHE && class->level != 3) {
pr_debug("class %u is a cache but not the L3", class->level);
continue;
}
if (!cpumask_equal(&class->affinity, cpu_possible_mask)) {
pr_debug("class %u does not cover all CPUs",
class->level);
continue;
}
if (cache_has_usable_csu(class)) {
pr_debug("class %u has usable CSU",
class->level);
/* CSU counters only make sense on a cache. */
switch (class->type) {
case MPAM_CLASS_CACHE:
counter_update_class(QOS_L3_OCCUP_EVENT_ID, class);
break;
default:
break;
}
}
}
}
static int mpam_resctrl_control_init(struct mpam_resctrl_res *res)
{
struct mpam_class *class = res->class;
@@ -1264,6 +1344,9 @@ int mpam_resctrl_setup(void)
}
}
/* Find some classes to use for monitors */
mpam_resctrl_pick_counters();
for_each_mpam_resctrl_mon(mon, eventid) {
if (!mon->class)
continue; // dummy resource