[RFC PATCH v2 1/5] arm_mpam: resctrl: Pick classes for use as mbm counters

[Ben Horgan]

From: James Morse <james.morse@xxxxxxx>

resctrl has two types of counters, NUMA-local and global. MPAM can only
count global either using MSC at the L3 cache or in the memory controllers.
When global and local equate to the same thing continue just to call it
global.

Tested-by: Shaopeng Tan <tan.shaopeng@xxxxxxxxxxxxxx>
Tested-by: Zeng Heng <zengheng4@xxxxxxxxxx>
Reviewed-by: Shaopeng Tan <tan.shaopeng@xxxxxxxxxxxxxx>
Reviewed-by: Jonathan Cameron <jonathan.cameron@xxxxxxxxxx>
Signed-off-by: James Morse <james.morse@xxxxxxx>
Signed-off-by: Ben Horgan <ben.horgan@xxxxxxx>
---
Changes since rfc v1:
Move finding any_mon_comp into monitor boilerplate patch
Move mpam_resctrl_get_domain_from_cpu() into monitor boilerplate
Remove free running check
Trim commit message
---
 drivers/resctrl/mpam_resctrl.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c
index a7691c66553a..c17577e52f58 100644
--- a/drivers/resctrl/mpam_resctrl.c
+++ b/drivers/resctrl/mpam_resctrl.c
@@ -598,6 +598,16 @@ static bool cache_has_usable_csu(struct mpam_class *class)
 	return true;
 }
 
+static bool class_has_usable_mbwu(struct mpam_class *class)
+{
+	struct mpam_props *cprops = &class->props;
+
+	if (!mpam_has_feature(mpam_feat_msmon_mbwu, cprops))
+		return false;
+
+	return true;
+}
+
 /*
  * Calculate the worst-case percentage change from each implemented step
  * in the control.
@@ -981,6 +991,22 @@ static void mpam_resctrl_pick_counters(void)
 				break;
 			}
 		}
+
+		if (class_has_usable_mbwu(class) &&
+		    topology_matches_l3(class) &&
+		    traffic_matches_l3(class)) {
+			pr_debug("class %u has usable MBWU, and matches L3 topology and traffic\n",
+				 class->level);
+
+			/*
+			 * We can't distinguish traffic by destination so
+			 * we don't know if it's staying on the same NUMA
+			 * node. Hence, we can't calculate mbm_local except
+			 * when we only have one L3 and it's equivalent to
+			 * mbm_total and so always use mbm_total.
+			 */
+			counter_update_class(QOS_L3_MBM_TOTAL_EVENT_ID, class);
+		}
 	}
 }
 
-- 
2.43.0