8369811: ZGC: Robust NUMA configuration detection

Co-authored-by: Axel Boldt-Christmas <aboldtch@openjdk.org>
Reviewed-by: aboldtch, sjohanss

src/hotspot/os/bsd/gc/z/zNUMA_bsd.cpp

@@ -46,3 +46,7 @@ uint32_t ZNUMA::memory_id(uintptr_t addr) {
   // NUMA support not enabled, assume everything belongs to node zero
   return 0;
 }
+
+int ZNUMA::numa_id_to_node(uint32_t numa_id) {
+  ShouldNotCallThis();
+}

src/hotspot/os/linux/gc/z/zNUMA_linux.cpp

@@ -32,12 +32,35 @@
 #include "runtime/os.hpp"
 #include "utilities/debug.hpp"
 
+static uint* z_numa_id_to_node = nullptr;
+static uint32_t* z_node_to_numa_id = nullptr;
+
 void ZNUMA::pd_initialize() {
   _enabled = UseNUMA;
 
+  size_t configured_nodes = 0;
+
+  if (UseNUMA) {
+    const size_t max_nodes = os::Linux::numa_num_configured_nodes();
+    z_numa_id_to_node = NEW_C_HEAP_ARRAY(uint, max_nodes, mtGC);
+    configured_nodes = os::numa_get_leaf_groups(z_numa_id_to_node, 0);
+
+    z_node_to_numa_id = NEW_C_HEAP_ARRAY(uint32_t, max_nodes, mtGC);
+
+    // Fill the array with invalid NUMA ids
+    for (uint32_t i = 0; i < max_nodes; i++) {
+      z_node_to_numa_id[i] = (uint32_t)-1;
+    }
+
+    // Fill the reverse mappings
+    for (uint32_t i = 0; i < configured_nodes; i++) {
+      z_node_to_numa_id[z_numa_id_to_node[i]] = i;
+    }
+  }
+
   // UseNUMA and is_faked() are mutually excluded in zArguments.cpp.
   _count = UseNUMA
-      ? os::Linux::numa_max_node() + 1
+      ? configured_nodes
       : !FLAG_IS_DEFAULT(ZFakeNUMA)
             ? ZFakeNUMA
             : 1;  // No NUMA nodes
@@ -54,7 +77,7 @@ uint32_t ZNUMA::id() {
     return 0;
   }
 
-  return os::Linux::get_node_by_cpu(ZCPU::id());
+  return z_node_to_numa_id[os::Linux::get_node_by_cpu(ZCPU::id())];
 }
 
 uint32_t ZNUMA::memory_id(uintptr_t addr) {
@@ -63,14 +86,21 @@ uint32_t ZNUMA::memory_id(uintptr_t addr) {
     return 0;
   }
 
-  uint32_t id = (uint32_t)-1;
+  int node = -1;
 
-  if (ZSyscall::get_mempolicy((int*)&id, nullptr, 0, (void*)addr, MPOL_F_NODE | MPOL_F_ADDR) == -1) {
+  if (ZSyscall::get_mempolicy(&node, nullptr, 0, (void*)addr, MPOL_F_NODE | MPOL_F_ADDR) == -1) {
     ZErrno err;
     fatal("Failed to get NUMA id for memory at " PTR_FORMAT " (%s)", addr, err.to_string());
   }
 
-  assert(id < _count, "Invalid NUMA id");
+  DEBUG_ONLY(const int max_nodes = os::Linux::numa_num_configured_nodes();)
+  assert(node < max_nodes, "NUMA node is out of bounds node=%d, max=%d", node, max_nodes);
 
-  return id;
+  return z_node_to_numa_id[node];
+}
+
+int ZNUMA::numa_id_to_node(uint32_t numa_id) {
+  assert(numa_id < _count, "NUMA id out of range 0 <= %ud <= %ud", numa_id, _count);
+
+  return (int)z_numa_id_to_node[numa_id];
 }

src/hotspot/os/linux/gc/z/zPhysicalMemoryBacking_linux.cpp

@@ -629,7 +629,7 @@ retry:
 
 size_t ZPhysicalMemoryBacking::commit_numa_preferred(zbacking_offset offset, size_t length, uint32_t numa_id) const {
   // Setup NUMA policy to allocate memory from a preferred node
-  os::Linux::numa_set_preferred((int)numa_id);
+  os::Linux::numa_set_preferred(ZNUMA::numa_id_to_node(numa_id));
 
   const size_t committed = commit_default(offset, length);
 

src/hotspot/os/windows/gc/z/zNUMA_windows.cpp

@@ -46,3 +46,7 @@ uint32_t ZNUMA::memory_id(uintptr_t addr) {
   // NUMA support not enabled, assume everything belongs to node zero
   return 0;
 }
+
+int ZNUMA::numa_id_to_node(uint32_t numa_id) {
+  ShouldNotCallThis();
+}

src/hotspot/share/gc/z/zNUMA.hpp

@@ -53,6 +53,8 @@ public:
   static size_t calculate_share(uint32_t numa_id, size_t total, size_t granule = ZGranuleSize, uint32_t ignore_count = 0);
 
   static const char* to_string();
+
+  static int numa_id_to_node(uint32_t numa_id);
 };
 
 #endif // SHARE_GC_Z_ZNUMA_HPP

src/hotspot/share/gc/z/zPhysicalMemoryManager.cpp

@@ -108,7 +108,7 @@ void ZPhysicalMemoryManager::try_enable_uncommit(size_t min_capacity, size_t max
   // Test if uncommit is supported by the operating system by committing
   // and then uncommitting a granule.
   const ZVirtualMemory vmem(zoffset(0), ZGranuleSize);
-  if (!commit(vmem, (uint32_t)-1) || !uncommit(vmem)) {
+  if (!commit(vmem, 0) || !uncommit(vmem)) {
     log_info_p(gc, init)("Uncommit: Implicitly Disabled (Not supported by operating system)");
     FLAG_SET_ERGO(ZUncommit, false);
     return;
@@ -293,7 +293,7 @@ void ZPhysicalMemoryManager::map(const ZVirtualMemory& vmem, uint32_t numa_id) c
 
   // Setup NUMA preferred for large pages
   if (ZNUMA::is_enabled() && ZLargePages::is_explicit()) {
-    os::numa_make_local((char*)addr, size, (int)numa_id);
+    os::numa_make_local((char*)addr, size, ZNUMA::numa_id_to_node(numa_id));
   }
 }