Re: [PATCH v6 04/16] sched/core: uclamp: Add CPU's clamp buckets refcounting

@@ -835,6 +954,28 @@ static void uclamp_bucket_inc(struct uclamp_se *uc_se, unsigned int clamp_id,
 	} while (!atomic_long_try_cmpxchg(&uc_maps[bucket_id].adata,
 					  &uc_map_old.data, uc_map_new.data));
 
+	/*
+	 * Ensure each CPU tracks the correct value for this clamp bucket.
+	 * This initialization of per-CPU variables is required only when a
+	 * clamp value is requested for the first time from a slow-path.
+	 */

+	if (unlikely(!uc_map_old.se_count)) {
+		for_each_possible_cpu(cpu) {
+			struct uclamp_cpu *uc_cpu =
+				&cpu_rq(cpu)->uclamp[clamp_id];
+
+			/* CPU's tasks count must be 0 for free buckets */
+			SCHED_WARN_ON(uc_cpu->bucket[bucket_id].tasks);
+			if (unlikely(uc_cpu->bucket[bucket_id].tasks))
+				uc_cpu->bucket[bucket_id].tasks = 0;
+
+			/* Minimize cache lines invalidation */
+			if (uc_cpu->bucket[bucket_id].value == bucket_value)
+				continue;
+			uc_cpu->bucket[bucket_id].value = bucket_value;
+		}
+	}
+
 	uc_se->value = clamp_value;
 	uc_se->bucket_id = bucket_id;