--- old/src/hotspot/os/solaris/os_solaris.cpp	2020-02-19 17:11:39.000000000 +0100
+++ new/src/hotspot/os/solaris/os_solaris.cpp	2020-02-19 17:11:39.000000000 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -3934,13 +3934,11 @@
       size_t lgrp_num = os::numa_get_leaf_groups(lgrp_ids, lgrp_limit);
       FREE_C_HEAP_ARRAY(int, lgrp_ids);
       if (lgrp_num < 2) {
-        // There's only one locality group, disable NUMA.
-        UseNUMA = false;
+        // There's only one locality group, disable NUMA unless
+        // user explicilty forces NUMA optimizations on single-node/UMA systems
+        UseNUMA = ForceNUMA;
       }
     }
-    if (!UseNUMA && ForceNUMA) {
-      UseNUMA = true;
-    }
   }
 
   Solaris::signal_sets_init();