hotspot/src/os/linux/vm/os_linux.cpp
changeset 20400 1c658ebcb3c1
parent 20005 6fb8070af25d
child 20408 ca559663042f
--- a/hotspot/src/os/linux/vm/os_linux.cpp	Thu Oct 03 21:36:29 2013 +0200
+++ b/hotspot/src/os/linux/vm/os_linux.cpp	Sat Oct 05 10:14:58 2013 +0200
@@ -3361,13 +3361,15 @@
   if (FLAG_IS_DEFAULT(UseHugeTLBFS) &&
       FLAG_IS_DEFAULT(UseSHM) &&
       FLAG_IS_DEFAULT(UseTransparentHugePages)) {
-    // If UseLargePages is specified on the command line try all methods,
-    // if it's default, then try only UseTransparentHugePages.
-    if (FLAG_IS_DEFAULT(UseLargePages)) {
-      UseTransparentHugePages = true;
-    } else {
-      UseHugeTLBFS = UseTransparentHugePages = UseSHM = true;
-    }
+
+    // The type of large pages has not been specified by the user.
+
+    // Try UseHugeTLBFS and then UseSHM.
+    UseHugeTLBFS = UseSHM = true;
+
+    // Don't try UseTransparentHugePages since there are known
+    // performance issues with it turned on. This might change in the future.
+    UseTransparentHugePages = false;
   }
 
   if (UseTransparentHugePages) {
@@ -3393,9 +3395,19 @@
 }
 
 void os::large_page_init() {
-  if (!UseLargePages) {
+  if (!UseLargePages &&
+      !UseTransparentHugePages &&
+      !UseHugeTLBFS &&
+      !UseSHM) {
+    // Not using large pages.
+    return;
+  }
+
+  if (!FLAG_IS_DEFAULT(UseLargePages) && !UseLargePages) {
+    // The user explicitly turned off large pages.
+    // Ignore the rest of the large pages flags.
+    UseTransparentHugePages = false;
     UseHugeTLBFS = false;
-    UseTransparentHugePages = false;
     UseSHM = false;
     return;
   }