6896099: Integrate CMS heap ergo with default heap sizing ergo

6627787: CMS: JVM refuses to start up with -Xms16m -Xmx16m
7000125: CMS: Anti-monotone young gen sizing with respect to maximum whole heap size specification
7027529: CMS: retire CMSUseOldDefaults flag
Summary: Simplify CMS heap sizing code, relying on ergonomic initial sizing consistent with other collectors for the most part, controlling only young gen sizing to rein in pause times. Make CMS young gen sizing default statically cpu-dependant. Remove inconsistencies wrt generation sizing and policy code, allowing for the fixing for 6627787 and 7000125. For 7027529, retire the flag CMSUseOldDefaults which had been introduced as a bridge from JDK 5 to JDK 6 a number of years ago.
Reviewed-by: brutisso, poonam

1 files changed, 10 insertions, 9 deletions

diff --git a/src/share/vm/memory/collectorPolicy.cpp b/src/share/vm/memory/collectorPolicy.cpp
index c609da68f..61efdd80f 100644
--- a/src/share/vm/memory/collectorPolicy.cpp
+++ b/src/share/vm/memory/collectorPolicy.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2011, 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
@@ -293,10 +293,11 @@ void GenCollectorPolicy::initialize_size_info() {
   // Determine maximum size of gen0
 
   size_t max_new_size = 0;
-  if (FLAG_IS_CMDLINE(MaxNewSize)) {
+  if (FLAG_IS_CMDLINE(MaxNewSize) || FLAG_IS_ERGO(MaxNewSize)) {
     if (MaxNewSize < min_alignment()) {
       max_new_size = min_alignment();
-    } else if (MaxNewSize >= max_heap_byte_size()) {
+    }
+    if (MaxNewSize >= max_heap_byte_size()) {
       max_new_size = align_size_down(max_heap_byte_size() - min_alignment(),
                                      min_alignment());
       warning("MaxNewSize (" SIZE_FORMAT "k) is equal to or "
@@ -333,7 +334,7 @@ void GenCollectorPolicy::initialize_size_info() {
   assert(max_new_size > 0, "All paths should set max_new_size");
 
   // Given the maximum gen0 size, determine the initial and
-  // minimum sizes.
+  // minimum gen0 sizes.
 
   if (max_heap_byte_size() == min_heap_byte_size()) {
     // The maximum and minimum heap sizes are the same so
@@ -396,7 +397,7 @@ void GenCollectorPolicy::initialize_size_info() {
   }
 
   if (PrintGCDetails && Verbose) {
-    gclog_or_tty->print_cr("Minimum gen0 " SIZE_FORMAT "  Initial gen0 "
+    gclog_or_tty->print_cr("1: Minimum gen0 " SIZE_FORMAT "  Initial gen0 "
       SIZE_FORMAT "  Maximum gen0 " SIZE_FORMAT,
       min_gen0_size(), initial_gen0_size(), max_gen0_size());
   }
@@ -448,7 +449,7 @@ void TwoGenerationCollectorPolicy::initialize_size_info() {
   // At this point the minimum, initial and maximum sizes
   // of the overall heap and of gen0 have been determined.
   // The maximum gen1 size can be determined from the maximum gen0
-  // and maximum heap size since not explicit flags exits
+  // and maximum heap size since no explicit flags exits
   // for setting the gen1 maximum.
   _max_gen1_size = max_heap_byte_size() - _max_gen0_size;
   _max_gen1_size =
@@ -494,13 +495,13 @@ void TwoGenerationCollectorPolicy::initialize_size_info() {
           "generation sizes: using maximum heap = " SIZE_FORMAT
           " -XX:OldSize flag is being ignored",
           max_heap_byte_size());
-  }
+    }
     // If there is an inconsistency between the OldSize and the minimum and/or
     // initial size of gen0, since OldSize was explicitly set, OldSize wins.
     if (adjust_gen0_sizes(&_min_gen0_size, &_min_gen1_size,
                           min_heap_byte_size(), OldSize)) {
       if (PrintGCDetails && Verbose) {
-        gclog_or_tty->print_cr("Minimum gen0 " SIZE_FORMAT "  Initial gen0 "
+        gclog_or_tty->print_cr("2: Minimum gen0 " SIZE_FORMAT "  Initial gen0 "
               SIZE_FORMAT "  Maximum gen0 " SIZE_FORMAT,
               min_gen0_size(), initial_gen0_size(), max_gen0_size());
       }
@@ -509,7 +510,7 @@ void TwoGenerationCollectorPolicy::initialize_size_info() {
     if (adjust_gen0_sizes(&_initial_gen0_size, &_initial_gen1_size,
                          initial_heap_byte_size(), OldSize)) {
       if (PrintGCDetails && Verbose) {
-        gclog_or_tty->print_cr("Minimum gen0 " SIZE_FORMAT "  Initial gen0 "
+        gclog_or_tty->print_cr("3: Minimum gen0 " SIZE_FORMAT "  Initial gen0 "
           SIZE_FORMAT "  Maximum gen0 " SIZE_FORMAT,
           min_gen0_size(), initial_gen0_size(), max_gen0_size());
       }