Merge tag 'sched-urgent-2021-12-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler fix from Thomas Gleixner:
 "A single fix for the x86 scheduler topology:

  Using cluster topology on hybrid CPUs, e.g. Alder Lake, biases the
  scheduler towards the ATOM cluster as that has more total capacity.
  Use selection based on CPU priority instead"

* tag 'sched-urgent-2021-12-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched,x86: Don't use cluster topology for x86 hybrid CPUs

Author: torvalds

arch/x86/kernel/smpboot.c

@@ -579,6 +579,17 @@ static struct sched_domain_topology_level x86_numa_in_package_topology[] = {
 	{ NULL, },
 };
 
+static struct sched_domain_topology_level x86_hybrid_topology[] = {
+#ifdef CONFIG_SCHED_SMT
+	{ cpu_smt_mask, x86_smt_flags, SD_INIT_NAME(SMT) },
+#endif
+#ifdef CONFIG_SCHED_MC
+	{ cpu_coregroup_mask, x86_core_flags, SD_INIT_NAME(MC) },
+#endif
+	{ cpu_cpu_mask, SD_INIT_NAME(DIE) },
+	{ NULL, },
+};
+
 static struct sched_domain_topology_level x86_topology[] = {
 #ifdef CONFIG_SCHED_SMT
 	{ cpu_smt_mask, x86_smt_flags, SD_INIT_NAME(SMT) },
@@ -1469,8 +1480,11 @@ void __init native_smp_cpus_done(unsigned int max_cpus)
 
 	calculate_max_logical_packages();
 
+	/* XXX for now assume numa-in-package and hybrid don't overlap */
 	if (x86_has_numa_in_package)
 		set_sched_topology(x86_numa_in_package_topology);
+	if (cpu_feature_enabled(X86_FEATURE_HYBRID_CPU))
+		set_sched_topology(x86_hybrid_topology);
 
 	nmi_selftest();
 	impress_friends();