Merge

hotspot/src/os/linux/vm/globals_linux.hpp

@@ -53,7 +53,7 @@
 // Defines Linux-specific default values. The flags are available on all
 // platforms, but they may have different default values on other platforms.
 //
-define_pd_global(bool, UseLargePages, true);
+define_pd_global(bool, UseLargePages, false);
 define_pd_global(bool, UseLargePagesIndividualAllocation, false);
 define_pd_global(bool, UseOSErrorReporting, false);
 define_pd_global(bool, UseThreadPriorities, true) ;

hotspot/src/os/linux/vm/os_linux.cpp

@@ -3361,13 +3361,15 @@ bool os::Linux::setup_large_page_type(size_t page_size) {
   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 @@ bool os::Linux::setup_large_page_type(size_t page_size) {
 }
 
 void os::large_page_init() {
-  if (!UseLargePages) {
-    UseHugeTLBFS = false;
+  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;
     UseSHM = false;
     return;
   }

hotspot/test/runtime/memory/LargePages/TestLargePagesFlags.java

@@ -0,0 +1,389 @@
+/*
+ * Copyright (c) 2013, 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/* @test TestLargePagesFlags
+ * @summary Tests how large pages are choosen depending on the given large pages flag combinations.
+ * @library /testlibrary
+ * @run main TestLargePagesFlags
+ */
+
+import com.oracle.java.testlibrary.OutputAnalyzer;
+import com.oracle.java.testlibrary.Platform;
+import com.oracle.java.testlibrary.ProcessTools;
+import java.util.ArrayList;
+
+public class TestLargePagesFlags {
+
+  public static void main(String [] args) throws Exception {
+    if (!Platform.isLinux()) {
+      System.out.println("Skipping. TestLargePagesFlags has only been implemented for Linux.");
+      return;
+    }
+
+    testUseTransparentHugePages();
+    testUseHugeTLBFS();
+    testUseSHM();
+    testCombinations();
+  }
+
+  public static void testUseTransparentHugePages() throws Exception {
+    if (!canUse(UseTransparentHugePages(true))) {
+      System.out.println("Skipping testUseTransparentHugePages");
+      return;
+    }
+
+    // -XX:-UseLargePages overrides all other flags.
+    new FlagTester()
+      .use(UseLargePages(false),
+           UseTransparentHugePages(true))
+      .expect(
+           UseLargePages(false),
+           UseTransparentHugePages(false),
+           UseHugeTLBFS(false),
+           UseSHM(false));
+
+    // Explicitly turn on UseTransparentHugePages.
+    new FlagTester()
+      .use(UseTransparentHugePages(true))
+      .expect(
+           UseLargePages(true),
+           UseTransparentHugePages(true),
+           UseHugeTLBFS(false),
+           UseSHM(false));
+
+    new FlagTester()
+      .use(UseLargePages(true),
+           UseTransparentHugePages(true))
+      .expect(
+           UseLargePages(true),
+           UseTransparentHugePages(true),
+           UseHugeTLBFS(false),
+           UseSHM(false));
+
+    // Setting a specific large pages flag will turn
+    // off heuristics to choose large pages type.
+    new FlagTester()
+      .use(UseLargePages(true),
+           UseTransparentHugePages(false))
+      .expect(
+           UseLargePages(false),
+           UseTransparentHugePages(false),
+           UseHugeTLBFS(false),
+           UseSHM(false));
+
+    // Don't turn on UseTransparentHugePages
+    // unless the user explicitly asks for them.
+    new FlagTester()
+      .use(UseLargePages(true))
+      .expect(
+           UseTransparentHugePages(false));
+  }
+
+  public static void testUseHugeTLBFS() throws Exception {
+    if (!canUse(UseHugeTLBFS(true))) {
+      System.out.println("Skipping testUseHugeTLBFS");
+      return;
+    }
+
+    // -XX:-UseLargePages overrides all other flags.
+    new FlagTester()
+      .use(UseLargePages(false),
+           UseHugeTLBFS(true))
+      .expect(
+           UseLargePages(false),
+           UseTransparentHugePages(false),
+           UseHugeTLBFS(false),
+           UseSHM(false));
+
+    // Explicitly turn on UseHugeTLBFS.
+    new FlagTester()
+      .use(UseHugeTLBFS(true))
+      .expect(
+           UseLargePages(true),
+           UseTransparentHugePages(false),
+           UseHugeTLBFS(true),
+           UseSHM(false));
+
+    new FlagTester()
+      .use(UseLargePages(true),
+           UseHugeTLBFS(true))
+      .expect(
+           UseLargePages(true),
+           UseTransparentHugePages(false),
+           UseHugeTLBFS(true),
+           UseSHM(false));
+
+    // Setting a specific large pages flag will turn
+    // off heuristics to choose large pages type.
+    new FlagTester()
+      .use(UseLargePages(true),
+           UseHugeTLBFS(false))
+      .expect(
+           UseLargePages(false),
+           UseTransparentHugePages(false),
+           UseHugeTLBFS(false),
+           UseSHM(false));
+
+    // Using UseLargePages will default to UseHugeTLBFS large pages.
+    new FlagTester()
+      .use(UseLargePages(true))
+      .expect(
+           UseLargePages(true),
+           UseTransparentHugePages(false),
+           UseHugeTLBFS(true),
+           UseSHM(false));
+  }
+
+  public static void testUseSHM() throws Exception {
+    if (!canUse(UseSHM(true))) {
+      System.out.println("Skipping testUseSHM");
+      return;
+    }
+
+    // -XX:-UseLargePages overrides all other flags.
+    new FlagTester()
+      .use(UseLargePages(false),
+           UseSHM(true))
+      .expect(
+           UseLargePages(false),
+           UseTransparentHugePages(false),
+           UseHugeTLBFS(false),
+           UseSHM(false));
+
+    // Explicitly turn on UseSHM.
+    new FlagTester()
+      .use(UseSHM(true))
+      .expect(
+           UseLargePages(true),
+           UseTransparentHugePages(false),
+           UseHugeTLBFS(false),
+           UseSHM(true)) ;
+
+    new FlagTester()
+      .use(UseLargePages(true),
+           UseSHM(true))
+      .expect(
+           UseLargePages(true),
+           UseTransparentHugePages(false),
+           UseHugeTLBFS(false),
+           UseSHM(true)) ;
+
+    // Setting a specific large pages flag will turn
+    // off heuristics to choose large pages type.
+    new FlagTester()
+      .use(UseLargePages(true),
+           UseSHM(false))
+      .expect(
+           UseLargePages(false),
+           UseTransparentHugePages(false),
+           UseHugeTLBFS(false),
+           UseSHM(false));
+
+    // Setting UseLargePages can allow the system to choose
+    // UseHugeTLBFS instead of UseSHM, but never UseTransparentHugePages.
+    new FlagTester()
+      .use(UseLargePages(true))
+      .expect(
+           UseLargePages(true),
+           UseTransparentHugePages(false));
+  }
+
+  public static void testCombinations() throws Exception {
+    if (!canUse(UseSHM(true)) || !canUse(UseHugeTLBFS(true))) {
+      System.out.println("Skipping testUseHugeTLBFSAndUseSHMCombination");
+      return;
+    }
+
+    // UseHugeTLBFS takes precedence over SHM.
+
+    new FlagTester()
+      .use(UseLargePages(true),
+           UseHugeTLBFS(true),
+           UseSHM(true))
+      .expect(
+           UseLargePages(true),
+           UseTransparentHugePages(false),
+           UseHugeTLBFS(true),
+           UseSHM(false));
+
+    new FlagTester()
+      .use(UseLargePages(true),
+           UseHugeTLBFS(false),
+           UseSHM(true))
+      .expect(
+           UseLargePages(true),
+           UseTransparentHugePages(false),
+           UseHugeTLBFS(false),
+           UseSHM(true));
+
+    new FlagTester()
+      .use(UseLargePages(true),
+           UseHugeTLBFS(true),
+           UseSHM(false))
+      .expect(
+           UseLargePages(true),
+           UseTransparentHugePages(false),
+           UseHugeTLBFS(true),
+           UseSHM(false));
+
+    new FlagTester()
+      .use(UseLargePages(true),
+           UseHugeTLBFS(false),
+           UseSHM(false))
+      .expect(
+           UseLargePages(false),
+           UseTransparentHugePages(false),
+           UseHugeTLBFS(false),
+           UseSHM(false));
+
+
+    if (!canUse(UseTransparentHugePages(true))) {
+      return;
+    }
+
+    // UseTransparentHugePages takes precedence.
+
+    new FlagTester()
+      .use(UseLargePages(true),
+           UseTransparentHugePages(true),
+           UseHugeTLBFS(true),
+           UseSHM(true))
+      .expect(
+           UseLargePages(true),
+           UseTransparentHugePages(true),
+           UseHugeTLBFS(false),
+           UseSHM(false));
+
+    new FlagTester()
+      .use(UseTransparentHugePages(true),
+           UseHugeTLBFS(true),
+           UseSHM(true))
+      .expect(
+           UseLargePages(true),
+           UseTransparentHugePages(true),
+           UseHugeTLBFS(false),
+           UseSHM(false));
+  }
+
+  private static class FlagTester {
+    private Flag [] useFlags;
+
+    public FlagTester use(Flag... useFlags) {
+      this.useFlags = useFlags;
+      return this;
+    }
+
+    public void expect(Flag... expectedFlags) throws Exception {
+      if (useFlags == null) {
+        throw new IllegalStateException("Must run use() before expect()");
+      }
+
+      OutputAnalyzer output = executeNewJVM(useFlags);
+
+      for (Flag flag : expectedFlags) {
+        System.out.println("Looking for: " + flag.flagString());
+        String strValue = output.firstMatch(".* " + flag.name() +  " .* :?= (\\S+).*", 1);
+
+        if (strValue == null) {
+          throw new RuntimeException("Flag " + flag.name() + " couldn't be found");
+        }
+
+        if (!flag.value().equals(strValue)) {
+          throw new RuntimeException("Wrong value for: " + flag.name()
+                                     + " expected: " + flag.value()
+                                     + " got: " + strValue);
+        }
+      }
+
+      output.shouldHaveExitValue(0);
+    }
+  }
+
+  private static OutputAnalyzer executeNewJVM(Flag... flags) throws Exception {
+    ArrayList<String> args = new ArrayList<>();
+    for (Flag flag : flags) {
+      args.add(flag.flagString());
+    }
+    args.add("-XX:+PrintFlagsFinal");
+    args.add("-version");
+
+    ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(args.toArray(new String[args.size()]));
+    OutputAnalyzer output = new OutputAnalyzer(pb.start());
+
+    return output;
+  }
+
+  private static boolean canUse(Flag flag) {
+    try {
+      new FlagTester().use(flag).expect(flag);
+    } catch (Exception e) {
+      return false;
+    }
+
+    return true;
+  }
+
+  private static Flag UseLargePages(boolean value) {
+    return new BooleanFlag("UseLargePages", value);
+  }
+
+  private static Flag UseTransparentHugePages(boolean value) {
+    return new BooleanFlag("UseTransparentHugePages", value);
+  }
+
+  private static Flag UseHugeTLBFS(boolean value) {
+    return new BooleanFlag("UseHugeTLBFS", value);
+  }
+
+  private static Flag UseSHM(boolean value) {
+    return new BooleanFlag("UseSHM", value);
+  }
+
+  private static class BooleanFlag implements Flag {
+    private String name;
+    private boolean value;
+
+    BooleanFlag(String name, boolean value) {
+      this.name = name;
+      this.value = value;
+    }
+
+    public String flagString() {
+      return "-XX:" + (value ? "+" : "-") + name;
+    }
+
+    public String name() {
+      return name;
+    }
+
+    public String value() {
+      return Boolean.toString(value);
+    }
+  }
+
+  private static interface Flag {
+    public String flagString();
+    public String name();
+    public String value();
+  }
+}