1 /*

     2  * Copyright (c) 2016, 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

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  *

    23  */

    24 

    25 #ifndef SHARE_VM_GC_G1_G1COLLECTIONSET_HPP

    26 #define SHARE_VM_GC_G1_G1COLLECTIONSET_HPP

    27 

    28 #include "gc/g1/collectionSetChooser.hpp"

    29 #include "memory/allocation.hpp"

    30 #include "utilities/debug.hpp"

    31 #include "utilities/globalDefinitions.hpp"

    32 

    33 class G1CollectedHeap;

    34 class G1CollectorPolicy;

    35 class G1CollectorState;

    36 class G1GCPhaseTimes;

    37 class HeapRegion;

    38 

    39 class G1CollectionSet VALUE_OBJ_CLASS_SPEC {

    40   G1CollectedHeap* _g1;

    41   G1CollectorPolicy* _policy;

    42 

    43   CollectionSetChooser* _cset_chooser;

    44 

    45   uint _eden_region_length;

    46   uint _survivor_region_length;

    47   uint _old_region_length;

    48 

    49   // The head of the list (via "next_in_collection_set()") representing the

    50   // current collection set. Set from the incrementally built collection

    51   // set at the start of the pause.

    52   HeapRegion* _head;

    53 

    54   // The number of bytes in the collection set before the pause. Set from

    55   // the incrementally built collection set at the start of an evacuation

    56   // pause, and incremented in finalize_old_part() when adding old regions

    57   // (if any) to the collection set.

    58   size_t _bytes_used_before;

    59 

    60   size_t _recorded_rs_lengths;

    61 

    62   // The associated information that is maintained while the incremental

    63   // collection set is being built with young regions. Used to populate

    64   // the recorded info for the evacuation pause.

    65 

    66   enum CSetBuildType {

    67     Active,             // We are actively building the collection set

    68     Inactive            // We are not actively building the collection set

    69   };

    70 

    71   CSetBuildType _inc_build_state;

    72 

    73   // The head of the incrementally built collection set.

    74   HeapRegion* _inc_head;

    75 

    76   // The tail of the incrementally built collection set.

    77   HeapRegion* _inc_tail;

    78 

    79   // The number of bytes in the incrementally built collection set.

    80   // Used to set _collection_set_bytes_used_before at the start of

    81   // an evacuation pause.

    82   size_t _inc_bytes_used_before;

    83 

    84   // The RSet lengths recorded for regions in the CSet. It is updated

    85   // by the thread that adds a new region to the CSet. We assume that

    86   // only one thread can be allocating a new CSet region (currently,

    87   // it does so after taking the Heap_lock) hence no need to

    88   // synchronize updates to this field.

    89   size_t _inc_recorded_rs_lengths;

    90 

    91   // A concurrent refinement thread periodically samples the young

    92   // region RSets and needs to update _inc_recorded_rs_lengths as

    93   // the RSets grow. Instead of having to synchronize updates to that

    94   // field we accumulate them in this field and add it to

    95   // _inc_recorded_rs_lengths_diffs at the start of a GC.

    96   ssize_t _inc_recorded_rs_lengths_diffs;

    97 

    98   // The predicted elapsed time it will take to collect the regions in

    99   // the CSet. This is updated by the thread that adds a new region to

   100   // the CSet. See the comment for _inc_recorded_rs_lengths about

   101   // MT-safety assumptions.

   102   double _inc_predicted_elapsed_time_ms;

   103 

   104   // See the comment for _inc_recorded_rs_lengths_diffs.

   105   double _inc_predicted_elapsed_time_ms_diffs;

   106 

   107   G1CollectorState* collector_state();

   108   G1GCPhaseTimes* phase_times();

   109 

   110   double predict_region_elapsed_time_ms(HeapRegion* hr);

   111 

   112 public:

   113   G1CollectionSet(G1CollectedHeap* g1h);

   114   ~G1CollectionSet();

   115 

   116   void set_policy(G1CollectorPolicy* g1p) {

   117     assert(_policy == NULL, "should only initialize once");

   118     _policy = g1p;

   119   }

   120 

   121   CollectionSetChooser* cset_chooser();

   122 

   123   void init_region_lengths(uint eden_cset_region_length,

   124                            uint survivor_cset_region_length);

   125 

   126   void set_recorded_rs_lengths(size_t rs_lengths);

   127 

   128   uint region_length() const       { return young_region_length() +

   129                                             old_region_length(); }

   130   uint young_region_length() const { return eden_region_length() +

   131                                             survivor_region_length(); }

   132 

   133   uint eden_region_length() const     { return _eden_region_length;     }

   134   uint survivor_region_length() const { return _survivor_region_length; }

   135   uint old_region_length() const      { return _old_region_length;      }

   136 

   137   // Incremental CSet Support

   138 

   139   // The head of the incrementally built collection set.

   140   HeapRegion* inc_head() { return _inc_head; }

   141 

   142   // The tail of the incrementally built collection set.

   143   HeapRegion* inc_tail() { return _inc_tail; }

   144 

   145   // Initialize incremental collection set info.

   146   void start_incremental_building();

   147 

   148   // Perform any final calculations on the incremental CSet fields

   149   // before we can use them.

   150   void finalize_incremental_building();

   151 

   152   void clear_incremental() {

   153     _inc_head = NULL;

   154     _inc_tail = NULL;

   155   }

   156 

   157   // Stop adding regions to the incremental collection set

   158   void stop_incremental_building() { _inc_build_state = Inactive; }

   159 

   160   // The head of the list (via "next_in_collection_set()") representing the

   161   // current collection set.

   162   HeapRegion* head() { return _head; }

   163 

   164   void clear_head() { _head = NULL; }

   165 

   166   size_t recorded_rs_lengths() { return _recorded_rs_lengths; }

   167 

   168   size_t bytes_used_before() const {

   169     return _bytes_used_before;

   170   }

   171 

   172   void reset_bytes_used_before() {

   173     _bytes_used_before = 0;

   174   }

   175 

   176   // Choose a new collection set.  Marks the chosen regions as being

   177   // "in_collection_set", and links them together.  The head and number of

   178   // the collection set are available via access methods.

   179   double finalize_young_part(double target_pause_time_ms);

   180   void finalize_old_part(double time_remaining_ms);

   181 

   182   // Add old region "hr" to the CSet.

   183   void add_old_region(HeapRegion* hr);

   184 

   185   // Update information about hr in the aggregated information for

   186   // the incrementally built collection set.

   187   void update_young_region_prediction(HeapRegion* hr, size_t new_rs_length);

   188 

   189   // Add hr to the LHS of the incremental collection set.

   190   void add_eden_region(HeapRegion* hr);

   191 

   192   // Add hr to the RHS of the incremental collection set.

   193   void add_survivor_regions(HeapRegion* hr);

   194 

   195 #ifndef PRODUCT

   196   void print(HeapRegion* list_head, outputStream* st);

   197 #endif // !PRODUCT

   198 

   199 private:

   200   // Update the incremental cset information when adding a region

   201   // (should not be called directly).

   202   void add_young_region_common(HeapRegion* hr);

   203 

   204 };

   205 

   206 #endif // SHARE_VM_GC_G1_G1COLLECTIONSET_HPP

   207