1 /*
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 3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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13  * accompanied this code).
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24 
25 #ifndef SHARE_GC_SHENANDOAH_SHENANDOAHGENERATIONSIZER_HPP
26 #define SHARE_GC_SHENANDOAH_SHENANDOAHGENERATIONSIZER_HPP
27 
28 #include "utilities/globalDefinitions.hpp"
29 
30 class ShenandoahGeneration;
31 class ShenandoahGenerationalHeap;
32 
33 class ShenandoahGenerationSizer {
34 private:
35   enum SizerKind {
36     SizerDefaults,
37     SizerNewSizeOnly,
38     SizerMaxNewSizeOnly,
39     SizerMaxAndNewSize,
40     SizerNewRatio
41   };
42   SizerKind _sizer_kind;
43 
44   size_t _min_desired_young_regions;
45   size_t _max_desired_young_regions;
46 
47   static size_t calculate_min_young_regions(size_t heap_region_count);
48   static size_t calculate_max_young_regions(size_t heap_region_count);
49 
50   // Update the given values for minimum and maximum young gen length in regions
51   // given the number of heap regions depending on the kind of sizing algorithm.
52   void recalculate_min_max_young_length(size_t heap_region_count);
53 
54   // This will attempt to transfer regions from the `src` generation to `dst` generation.
55   // If the transfer would violate the configured minimum size for the source or the configured
56   // maximum size of the destination, it will not perform the transfer and will return false.
57   // Returns true if the transfer is performed.
58   bool transfer_regions(ShenandoahGeneration* src, ShenandoahGeneration* dst, size_t regions) const;
59 
60   // Return the configured maximum size in bytes for the given generation.
61   size_t max_size_for(ShenandoahGeneration* generation) const;
62 
63   // Return the configured minimum size in bytes for the given generation.
64   size_t min_size_for(ShenandoahGeneration* generation) const;
65 
66 public:
67   ShenandoahGenerationSizer();
68 
69   // Calculate the maximum length of the young gen given the number of regions
70   // depending on the sizing algorithm.
71   void heap_size_changed(size_t heap_size);
72 
73   // Minimum size of young generation in bytes as multiple of region size.
74   size_t min_young_size() const;
75   size_t min_young_regions() const {
76     return _min_desired_young_regions;
77   }
78 
79   // Maximum size of young generation in bytes as multiple of region size.
80   size_t max_young_size() const;
81   size_t max_young_regions() const {
82     return _max_desired_young_regions;
83   }
84 
85   // True if transfer succeeds, else false. See transfer_regions.
86   bool transfer_to_young(size_t regions) const;
87   bool transfer_to_old(size_t regions) const;
88 
89   // force transfer is used when we promote humongous objects.  May violate min/max limits on generation sizes
90   void force_transfer_to_old(size_t regions) const;
91 };
92 
93 #endif //SHARE_GC_SHENANDOAH_SHENANDOAHGENERATIONSIZER_HPP