1 #ifdef USE_PRAGMA_IDENT_HDR
   2 #pragma ident "@(#)ageTable.hpp 1.29 07/05/05 17:05:32 JVM"
   3 #endif
   4 /*
   5  * Copyright 1997-2003 Sun Microsystems, Inc.  All Rights Reserved.
   6  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   7  *
   8  * This code is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU General Public License version 2 only, as
  10  * published by the Free Software Foundation.
  11  *
  12  * This code is distributed in the hope that it will be useful, but WITHOUT
  13  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15  * version 2 for more details (a copy is included in the LICENSE file that
  16  * accompanied this code).
  17  *
  18  * You should have received a copy of the GNU General Public License version
  19  * 2 along with this work; if not, write to the Free Software Foundation,
  20  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  21  *
  22  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  23  * CA 95054 USA or visit www.sun.com if you need additional information or
  24  * have any questions.
  25  *  
  26  */
  27 
  28 /* Copyright 1992 Sun Microsystems, Inc. and Stanford University.
  29    See the LICENSE file for license information. */
  30 
  31 // Age table for adaptive feedback-mediated tenuring (scavenging)
  32 //
  33 // Note: all sizes are in oops
  34 
  35 class ageTable VALUE_OBJ_CLASS_SPEC {
  36   friend class VMStructs;
  37 
  38  public:
  39   // constants
  40   enum { table_size = markOopDesc::max_age + 1 };
  41 
  42   // instance variables
  43   size_t sizes[table_size];
  44 
  45   // constructor.  "global" indicates that this is the global age table
  46   // (as opposed to gc-thread-local)
  47   ageTable(bool global = true);
  48 
  49   // clear table
  50   void clear();
  51 
  52   // add entry
  53   void add(oop p, size_t oop_size) {
  54     int age = p->age();
  55     assert(age > 0 && age < table_size, "invalid age of object");
  56     sizes[age] += oop_size; 
  57   }
  58 
  59   // Merge another age table with the current one.  Used
  60   // for parallel young generation gc.
  61   void merge(ageTable* subTable);
  62 
  63   // calculate new tenuring threshold based on age information
  64   int compute_tenuring_threshold(size_t survivor_capacity);
  65 
  66  private:
  67   PerfVariable* _perf_sizes[table_size];
  68 };