--- old/src/hotspot/os/aix/os_aix.cpp	2020-05-02 05:24:27.990484263 -0400
+++ new/src/hotspot/os/aix/os_aix.cpp	2020-05-02 05:24:27.682474342 -0400
@@ -3549,10 +3549,9 @@
     return JNI_ERR;
   }
 
-  if (UseNUMA) {
-    UseNUMA = false;
-    warning("NUMA optimizations are not available on this OS.");
-  }
+  // Not supported.
+  FLAG_SET_ERGO(UseNUMA, false);
+  FLAG_SET_ERGO(UseNUMAInterleaving, false);
 
   if (MaxFDLimit) {
     // Set the number of file descriptors to max. print out error
--- old/src/hotspot/os/bsd/os_bsd.cpp	2020-05-02 05:24:29.114520470 -0400
+++ new/src/hotspot/os/bsd/os_bsd.cpp	2020-05-02 05:24:28.746508616 -0400
@@ -3140,6 +3140,10 @@
     return JNI_ERR;
   }
 
+  // Not supported.
+  FLAG_SET_ERGO(UseNUMA, false);
+  FLAG_SET_ERGO(UseNUMAInterleaving, false);
+
   if (MaxFDLimit) {
     // set the number of file descriptors to max. print out error
     // if getrlimit/setrlimit fails but continue regardless.
--- old/src/hotspot/os/linux/os_linux.cpp	2020-05-02 05:24:30.226556291 -0400
+++ new/src/hotspot/os/linux/os_linux.cpp	2020-05-02 05:24:29.862544566 -0400
@@ -5175,7 +5175,8 @@
   // bitmask when externally configured to run on all or fewer nodes.
 
   if (!Linux::libnuma_init()) {
-    UseNUMA = false;
+    FLAG_SET_ERGO(UseNUMA, false);
+    FLAG_SET_ERGO(UseNUMAInterleaving, false); // Also depends on libnuma.
   } else {
     if ((Linux::numa_max_node() < 1) || Linux::is_bound_to_single_node()) {
       // If there's only one node (they start from 0) or if the process
@@ -5208,6 +5209,11 @@
     }
   }
 
+  // When NUMA requested, not-NUMA-aware allocations default to interleaving.
+  if (UseNUMA && !UseNUMAInterleaving) {
+    FLAG_SET_ERGO_IF_DEFAULT(UseNUMAInterleaving, true);
+  }
+
   if (UseParallelGC && UseNUMA && UseLargePages && !can_commit_large_page_memory()) {
     // With SHM and HugeTLBFS large pages we cannot uncommit a page, so there's no way
     // we can make the adaptive lgrp chunk resizing work. If the user specified both
@@ -5272,7 +5278,7 @@
   log_info(os)("HotSpot is running with %s, %s",
                Linux::glibc_version(), Linux::libpthread_version());
 
-  if (UseNUMA) {
+  if (UseNUMA || UseNUMAInterleaving) {
     Linux::numa_init();
   }
 
--- old/src/hotspot/os/solaris/os_solaris.cpp	2020-05-02 05:24:31.342592240 -0400
+++ new/src/hotspot/os/solaris/os_solaris.cpp	2020-05-02 05:24:30.978580515 -0400
@@ -3916,7 +3916,7 @@
 
   if (UseNUMA) {
     if (!Solaris::liblgrp_init()) {
-      UseNUMA = false;
+      FLAG_SET_ERGO(UseNUMA, false);
     } else {
       size_t lgrp_limit = os::numa_get_groups_num();
       int *lgrp_ids = NEW_C_HEAP_ARRAY(int, lgrp_limit, mtInternal);
@@ -3930,6 +3930,11 @@
     }
   }
 
+  // When NUMA requested, not-NUMA-aware allocations default to interleaving.
+  if (UseNUMA && !UseNUMAInterleaving) {
+    FLAG_SET_ERGO_IF_DEFAULT(UseNUMAInterleaving, true);
+  }
+
   Solaris::signal_sets_init();
   Solaris::init_signal_mem();
   Solaris::install_signal_handlers();
--- old/src/hotspot/os/windows/os_windows.cpp	2020-05-02 05:24:32.458628191 -0400
+++ new/src/hotspot/os/windows/os_windows.cpp	2020-05-02 05:24:32.090616336 -0400
@@ -4096,10 +4096,13 @@
     UseNUMA = false; // We don't fully support this yet
   }
 
-  if (UseNUMAInterleaving) {
-    // first check whether this Windows OS supports VirtualAllocExNuma, if not ignore this flag
-    bool success = numa_interleaving_init();
-    if (!success) UseNUMAInterleaving = false;
+  if (UseNUMAInterleaving || (UseNUMA && FLAG_IS_DEFAULT(UseNUMAInterleaving))) {
+    if (!numa_interleaving_init()) {
+      FLAG_SET_ERGO(UseNUMAInterleaving, false);
+    } else if (!UseNUMAInterleaving) {
+      // When NUMA requested, not-NUMA-aware allocations default to interleaving.
+      FLAG_SET_ERGO(UseNUMAInterleaving, true);
+    }
   }
 
   if (initSock() != JNI_OK) {
--- old/src/hotspot/share/runtime/arguments.cpp	2020-05-02 05:24:33.570664011 -0400
+++ new/src/hotspot/share/runtime/arguments.cpp	2020-05-02 05:24:33.214652543 -0400
@@ -4158,14 +4158,6 @@
          FLAG_SET_DEFAULT(MinHeapDeltaBytes, 64*M);
       }
     }
-    // UseNUMAInterleaving is set to ON for all collectors and platforms when
-    // UseNUMA is set to ON. NUMA-aware collectors will interleave old gen and
-    // survivor spaces on top of NUMA allocation policy for the eden space.
-    // Non NUMA-aware collectors will interleave all of the heap spaces across
-    // NUMA nodes.
-    if (FLAG_IS_DEFAULT(UseNUMAInterleaving)) {
-      FLAG_SET_ERGO(UseNUMAInterleaving, true);
-    }
   }
   return JNI_OK;
 }