sched/debug: Print the local group's asym_prefer_cpu

Add a file to read local group's "asym_prefer_cpu" from debugfs. This
information was useful when debugging issues where "asym_prefer_cpu" was
incorrectly set to a CPU with a lower asym priority.

Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250409053446.23367-5-kprateek.nayak@amd.com

Author: kudureranganath

kernel/sched/debug.c

@@ -588,6 +588,10 @@ static void register_sd(struct sched_domain *sd, struct dentry *parent)
 	debugfs_create_file("flags", 0444, parent, &sd->flags, &sd_flags_fops);
 	debugfs_create_file("groups_flags", 0444, parent, &sd->groups->flags, &sd_flags_fops);
 	debugfs_create_u32("level", 0444, parent, (u32 *)&sd->level);
+
+	if (sd->flags & SD_ASYM_PACKING)
+		debugfs_create_u32("group_asym_prefer_cpu", 0444, parent,
+				   (u32 *)&sd->groups->asym_prefer_cpu);
 }
 
 void update_sched_domain_debugfs(void)