rev 60542 : [mq]: 8245511-rev.3

   1 /*
   2  * Copyright (c) 2015, 2020, 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_GC_G1_G1IHOPCONTROL_HPP
  26 #define SHARE_GC_G1_G1IHOPCONTROL_HPP
  27 
  28 #include "gc/g1/g1OldGenAllocationTracker.hpp"
  29 #include "memory/allocation.hpp"
  30 #include "utilities/numberSeq.hpp"
  31 
  32 class G1Predictions;
  33 class G1NewTracer;
  34 
  35 // Base class for algorithms that calculate the heap occupancy at which
  36 // concurrent marking should start. This heap usage threshold should be relative
  37 // to old gen size.
  38 class G1IHOPControl : public CHeapObj<mtGC> {
  39  protected:
  40   // The initial IHOP value relative to the target occupancy.
  41   double _initial_ihop_percent;
  42   // The target maximum occupancy of the heap. The target occupancy is the number
  43   // of bytes when marking should be finished and reclaim started.
  44   size_t _target_occupancy;
  45 
  46   // Most recent complete mutator allocation period in seconds.
  47   double _last_allocation_time_s;
  48 
  49   const G1OldGenAllocationTracker* _old_gen_alloc_tracker;
  50   // Initialize an instance with the old gen allocation tracker and the
  51   // initial IHOP value in percent. The target occupancy will be updated
  52   // at the first heap expansion.
  53   G1IHOPControl(double ihop_percent, G1OldGenAllocationTracker const* old_gen_alloc_tracker);
  54 
  55   // Most recent time from the end of the concurrent start to the start of the first
  56   // mixed gc.
  57   virtual double last_marking_length_s() const = 0;
  58  public:
  59   virtual ~G1IHOPControl() { }
  60 
  61   // Get the current non-young occupancy at which concurrent marking should start.
  62   virtual size_t get_conc_mark_start_threshold() = 0;
  63 
  64   // Adjust target occupancy.
  65   virtual void update_target_occupancy(size_t new_target_occupancy);
  66   // Update information about time during which allocations in the Java heap occurred,
  67   // how large these allocations were in bytes, and an additional buffer.
  68   // The allocations should contain any amount of space made unusable for further
  69   // allocation, e.g. any waste caused by TLAB allocation, space at the end of
  70   // humongous objects that can not be used for allocation, etc.
  71   // Together with the target occupancy, this additional buffer should contain the
  72   // difference between old gen size and total heap size at the start of reclamation,
  73   // and space required for that reclamation.
  74   virtual void update_allocation_info(double allocation_time_s, size_t additional_buffer_size);
  75   // Update the time spent in the mutator beginning from the end of concurrent start to
  76   // the first mixed gc.
  77   virtual void update_marking_length(double marking_length_s) = 0;
  78 
  79   virtual void print();
  80   virtual void send_trace_event(G1NewTracer* tracer);
  81 };
  82 
  83 // The returned concurrent mark starting occupancy threshold is a fixed value
  84 // relative to the maximum heap size.
  85 class G1StaticIHOPControl : public G1IHOPControl {
  86   // Most recent mutator time between the end of concurrent mark to the start of the
  87   // first mixed gc.
  88   double _last_marking_length_s;
  89  protected:
  90   double last_marking_length_s() const { return _last_marking_length_s; }
  91  public:
  92   G1StaticIHOPControl(double ihop_percent, G1OldGenAllocationTracker const* old_gen_alloc_tracker);
  93 
  94   size_t get_conc_mark_start_threshold() {
  95     guarantee(_target_occupancy > 0, "Target occupancy must have been initialized.");
  96     return (size_t) (_initial_ihop_percent * _target_occupancy / 100.0);
  97   }
  98 
  99   virtual void update_marking_length(double marking_length_s) {
 100    assert(marking_length_s > 0.0, "Marking length must be larger than zero but is %.3f", marking_length_s);
 101     _last_marking_length_s = marking_length_s;
 102   }
 103 };
 104 
 105 // This algorithm tries to return a concurrent mark starting occupancy value that
 106 // makes sure that during marking the given target occupancy is never exceeded,
 107 // based on predictions of current allocation rate and time periods between
 108 // concurrent start and the first mixed gc.
 109 class G1AdaptiveIHOPControl : public G1IHOPControl {
 110   size_t _heap_reserve_percent; // Percentage of maximum heap capacity we should avoid to touch
 111   size_t _heap_waste_percent;   // Percentage of free heap that should be considered as waste.
 112 
 113   const G1Predictions * _predictor;
 114 
 115   TruncatedSeq _marking_times_s;
 116   TruncatedSeq _allocation_rate_s;
 117 
 118   // The most recent unrestrained size of the young gen. This is used as an additional
 119   // factor in the calculation of the threshold, as the threshold is based on
 120   // non-young gen occupancy at the end of GC. For the IHOP threshold, we need to
 121   // consider the young gen size during that time too.
 122   // Since we cannot know what young gen sizes are used in the future, we will just
 123   // use the current one. We expect that this one will be one with a fairly large size,
 124   // as there is no marking or mixed gc that could impact its size too much.
 125   size_t _last_unrestrained_young_size;
 126 
 127   // Get a new prediction bounded below by zero from the given sequence.
 128   double predict(TruncatedSeq const* seq) const;
 129 
 130   bool have_enough_data_for_prediction() const;
 131 
 132   // The "actual" target threshold the algorithm wants to keep during and at the
 133   // end of marking. This is typically lower than the requested threshold, as the
 134   // algorithm needs to consider restrictions by the environment.
 135   size_t actual_target_threshold() const;
 136 
 137   // This method calculates the old gen allocation rate based on the net survived
 138   // bytes that are allocated in the old generation in the last mutator period.




 139   double last_mutator_period_old_allocation_rate() const;
 140  protected:
 141   virtual double last_marking_length_s() const { return _marking_times_s.last(); }
 142  public:
 143   G1AdaptiveIHOPControl(double ihop_percent,
 144                         G1OldGenAllocationTracker const* old_gen_alloc_tracker,
 145                         G1Predictions const* predictor,
 146                         size_t heap_reserve_percent, // The percentage of total heap capacity that should not be tapped into.
 147                         size_t heap_waste_percent);  // The percentage of the free space in the heap that we think is not usable for allocation.
 148 
 149   virtual size_t get_conc_mark_start_threshold();
 150 
 151   virtual void update_allocation_info(double allocation_time_s, size_t additional_buffer_size);
 152   virtual void update_marking_length(double marking_length_s);
 153 
 154   virtual void print();
 155   virtual void send_trace_event(G1NewTracer* tracer);
 156 };
 157 
 158 #endif // SHARE_GC_G1_G1IHOPCONTROL_HPP
--- EOF ---