1 /*
 2  * Copyright (c) 1997, 2021, Oracle and/or its affiliates. All rights reserved.
 3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 4  *
 5  * This code is free software; you can redistribute it and/or modify it
 6  * under the terms of the GNU General Public License version 2 only, as
 7  * published by the Free Software Foundation.
 8  *
 9  * This code is distributed in the hope that it will be useful, but WITHOUT
10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12  * version 2 for more details (a copy is included in the LICENSE file that
13  * accompanied this code).
14  *
15  * You should have received a copy of the GNU General Public License version
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17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18  *
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24 
25 #ifndef SHARE_GC_SHARED_AGETABLE_HPP
26 #define SHARE_GC_SHARED_AGETABLE_HPP
27 
28 #include "memory/allocation.hpp"
29 #include "oops/markWord.hpp"
30 #include "oops/oop.hpp"
31 #include "runtime/perfDataTypes.hpp"
32 
33 /* Copyright (c) 1992, 2021, Oracle and/or its affiliates, and Stanford University.
34    See the LICENSE file for license information. */
35 
36 // Age table for adaptive feedback-mediated tenuring (scavenging)
37 //
38 // Note: all sizes are in oops
39 
40 class AgeTable: public CHeapObj<mtGC> {
41   friend class VMStructs;
42 
43  public:
44   // constants
45   enum { table_size = markWord::max_age + 1 };
46 
47   // instance variables
48   size_t sizes[table_size];
49 
50   // constructor.  "global" indicates that this is the global age table
51   // (as opposed to gc-thread-local)
52   AgeTable(bool global = true);
53 
54   // clear table
55   void clear();
56   // check whether it's clear
57   bool is_clear() PRODUCT_RETURN0;
58 
59   // add entry
60   inline void add(oop p, size_t oop_size);
61 
62   void add(uint age, size_t oop_size) {
63     assert(age < table_size, "invalid age of object");
64     sizes[age] += oop_size;
65   }
66 
67   // Merge another age table with the current one.
68   void merge(const AgeTable* subTable);
69 
70   // Calculate new tenuring threshold based on age information.
71   uint compute_tenuring_threshold(size_t desired_survivor_size);
72   void print_age_table(uint tenuring_threshold);
73   void print_on(outputStream* st, uint tenuring_threshold);
74 
75  private:
76   bool _use_perf_data;
77   PerfVariable* _perf_sizes[table_size];
78 };
79 
80 #endif // SHARE_GC_SHARED_AGETABLE_HPP