8289137: Automatically adapt Young/OldPLABSize and when setting only MinTLABSize

src/hotspot/share/gc/shared/plab.cpp

@@ -31,6 +31,7 @@
 #include "logging/log.hpp"
 #include "memory/universe.hpp"
 #include "oops/oop.inline.hpp"
+#include "runtime/globals_extension.hpp"
 
 size_t PLAB::min_size() {
   // Make sure that we return something that is larger than AlignmentReserve
@@ -41,6 +42,17 @@ size_t PLAB::max_size() {
   return ThreadLocalAllocBuffer::max_size();
 }
 
+void PLAB::startup_initialization() {
+  if (!FLAG_IS_DEFAULT(MinTLABSize)) {
+    if (FLAG_IS_DEFAULT(YoungPLABSize)) {
+      FLAG_SET_ERGO(YoungPLABSize, MAX2(ThreadLocalAllocBuffer::min_size(), YoungPLABSize));
+    }
+    if (FLAG_IS_DEFAULT(OldPLABSize)) {
+      FLAG_SET_ERGO(OldPLABSize, MAX2(ThreadLocalAllocBuffer::min_size(), OldPLABSize));
+    }
+  }
+}
+
 PLAB::PLAB(size_t desired_plab_sz_) :
   _word_sz(desired_plab_sz_), _bottom(NULL), _top(NULL),
   _end(NULL), _hard_end(NULL), _allocated(0), _wasted(0), _undo_wasted(0)

src/hotspot/share/gc/shared/plab.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2022, 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
@@ -69,6 +69,8 @@ class PLAB: public CHeapObj<mtGC> {
   void undo_last_allocation(HeapWord* obj, size_t word_sz);
 
 public:
+  static void startup_initialization();
+
   // Initializes the buffer to be empty, but with the given "word_sz".
   // Must get initialized with "set_buf" for an allocation to succeed.
   PLAB(size_t word_sz);

src/hotspot/share/memory/universe.cpp

@@ -43,6 +43,7 @@
 #include "gc/shared/gcLogPrecious.hpp"
 #include "gc/shared/gcTraceTime.inline.hpp"
 #include "gc/shared/oopStorageSet.hpp"
+#include "gc/shared/plab.hpp"
 #include "gc/shared/stringdedup/stringDedup.hpp"
 #include "gc/shared/tlab_globals.hpp"
 #include "logging/log.hpp"
@@ -840,6 +841,7 @@ jint Universe::initialize_heap() {
 
 void Universe::initialize_tlab() {
   ThreadLocalAllocBuffer::set_max_size(Universe::heap()->max_tlab_size());
+  PLAB::startup_initialization();
   if (UseTLAB) {
     ThreadLocalAllocBuffer::startup_initialization();
   }

test/hotspot/jtreg/gc/TestPLABAdaptToMinTLABSize.java

@@ -0,0 +1,77 @@
+/*
+ * Copyright (c) 2022, 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.
+ */
+
+package gc.g1;
+
+/*
+ * @test TestPLABAdaptToMinTLABSize
+ * @bug 8289137
+ * @summary Make sure that Young/OldPLABSize adapt to MinTLABSize setting.
+ * @library /test/lib
+ * @modules java.base/jdk.internal.misc
+ *          java.management
+ * @run driver gc.g1.TestPLABAdaptToMinTLABSize
+ */
+
+import java.util.ArrayList;
+import java.util.Collections;
+
+import jdk.test.lib.process.OutputAnalyzer;
+import jdk.test.lib.process.ProcessTools;
+
+public class TestPLABAdaptToMinTLABSize {
+    private static void runTest(boolean shouldSucceed, String... extraArgs) throws Exception {
+        ArrayList<String> testArguments = new ArrayList<String>();
+        testArguments.add("-Xmx12m");
+        testArguments.add("-XX:+PrintFlagsFinal");
+        Collections.addAll(testArguments, extraArgs);
+        testArguments.add("-version");
+
+        ProcessBuilder pb = ProcessTools.createTestJvm(testArguments);
+
+        OutputAnalyzer output = new OutputAnalyzer(pb.start());
+
+        System.out.println(output.getStderr());
+
+        if (shouldSucceed) {
+            output.shouldHaveExitValue(0);
+
+            long oldPLABSize = Long.parseLong(output.firstMatch("OldPLABSize\\s+=\\s(\\d+)",1));
+            long youngPLABSize = Long.parseLong(output.firstMatch("YoungPLABSize\\s+=\\s(\\d+)",1));
+            long minTLABSize = Long.parseLong(output.firstMatch("MinTLABSize\\s+=\\s(\\d+)",1));
+
+            System.out.println("OldPLABSize=" + oldPLABSize + " YoungPLABSize=" + youngPLABSize +
+                               "MinTLABSize=" + minTLABSize);
+
+        } else {
+            output.shouldNotHaveExitValue(0);
+        }
+    }
+
+    public static void main(String[] args) throws Exception {
+        runTest(true, "-XX:MinTLABSize=100k");
+        // Should not succeed when explicitly specifying invalid combination.
+        runTest(false, "-XX:MinTLABSize=100k", "-XX:OldPLABSize=5k");
+        runTest(false, "-XX:MinTLABSize=100k", "-XX:YoungPLABSize=5k");
+    }
+}