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
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 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).
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24 
25 #ifndef SHARE_GC_SHARED_AGETABLE_HPP
26 #define SHARE_GC_SHARED_AGETABLE_HPP
27 
28 #include "oops/markWord.hpp"
29 #include "oops/oop.hpp"
30 #include "runtime/perfDataTypes.hpp"
31 
32 /* Copyright (c) 1992, 2021, Oracle and/or its affiliates, and Stanford University.
33    See the LICENSE file for license information. */
34 
35 // Age table for adaptive feedback-mediated tenuring (scavenging)
36 //
37 // Note: all sizes are in oops
38 
39 class AgeTable {
40   friend class VMStructs;
41 
42  public:
43   // constants
44   enum { table_size = markWord::max_age + 1 };
45 
46   // instance variables
47   size_t sizes[table_size];
48 
49   // constructor.  "global" indicates that this is the global age table
50   // (as opposed to gc-thread-local)
51   AgeTable(bool global = true);
52 
53   // clear table
54   void clear();
55 
56   // add entry
57   inline void add(oop p, size_t oop_size);
58 
59   void add(uint age, size_t oop_size) {
60     assert(age > 0 && age < table_size, "invalid age of object");
61     sizes[age] += oop_size;
62   }
63 
64   // Merge another age table with the current one.  Used
65   // for parallel young generation gc.
66   void merge(const AgeTable* subTable);
67 
68   // Calculate new tenuring threshold based on age information.
69   uint compute_tenuring_threshold(size_t desired_survivor_size);
70   void print_age_table(uint tenuring_threshold);
71   void print_on(outputStream* st, uint tenuring_threshold);
72 
73  private:
74   bool _use_perf_data;
75   PerfVariable* _perf_sizes[table_size];
76 };
77 
78 #endif // SHARE_GC_SHARED_AGETABLE_HPP
--- EOF ---