annotate src/share/vm/gc_implementation/parallelScavenge/asPSOldGen.cpp @ 453:c96030fff130

6684579: SoftReference processing can be made more efficient Summary: For current soft-ref clearing policies, we can decide at marking time if a soft-reference will definitely not be cleared, postponing the decision of whether it will definitely be cleared to the final reference processing phase. This can be especially beneficial in the case of concurrent collectors where the marking is usually concurrent but reference processing is usually not. Reviewed-by: jmasa
author ysr
date Thu, 20 Nov 2008 16:56:09 -0800
parents a61af66fc99e
children c18cbe5936b8
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1 /*
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2 * Copyright 2003-2006 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 # include "incls/_precompiled.incl"
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26 # include "incls/_asPSOldGen.cpp.incl"
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27
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28 // Whereas PSOldGen takes the maximum size of the generation
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29 // (which doesn't change in the case of PSOldGen) as a parameter,
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30 // ASPSOldGen takes the upper limit on the size of
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31 // the generation as a parameter. In ASPSOldGen the
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32 // maximum size of the generation can change as the boundary
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33 // moves. The "maximum size of the generation" is still a valid
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34 // concept since the generation can grow and shrink within that
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35 // maximum. There are lots of useful checks that use that
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36 // maximum. In PSOldGen the method max_gen_size() returns
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37 // _max_gen_size (as set by the PSOldGen constructor). This
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38 // is how it always worked. In ASPSOldGen max_gen_size()
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39 // returned the size of the reserved space for the generation.
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40 // That can change as the boundary moves. Below the limit of
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41 // the size of the generation is passed to the PSOldGen constructor
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42 // for "_max_gen_size" (have to pass something) but it is not used later.
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43 //
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44 ASPSOldGen::ASPSOldGen(size_t initial_size,
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45 size_t min_size,
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46 size_t size_limit,
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47 const char* gen_name,
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48 int level) :
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49 PSOldGen(initial_size, min_size, size_limit, gen_name, level),
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50 _gen_size_limit(size_limit)
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51
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52 {}
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53
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54 ASPSOldGen::ASPSOldGen(PSVirtualSpace* vs,
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55 size_t initial_size,
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56 size_t min_size,
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57 size_t size_limit,
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58 const char* gen_name,
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59 int level) :
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60 PSOldGen(initial_size, min_size, size_limit, gen_name, level),
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61 _gen_size_limit(size_limit)
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62
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63 {
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64 _virtual_space = vs;
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65 }
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66
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67 void ASPSOldGen::reset_after_change() {
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68 _reserved = MemRegion((HeapWord*)virtual_space()->low_boundary(),
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69 (HeapWord*)virtual_space()->high_boundary());
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70 post_resize();
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71 }
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72
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73
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74 size_t ASPSOldGen::available_for_expansion() {
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75 assert(virtual_space()->is_aligned(gen_size_limit()), "not aligned");
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76 assert(gen_size_limit() >= virtual_space()->committed_size(), "bad gen size");
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77
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78 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
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79 size_t result = gen_size_limit() - virtual_space()->committed_size();
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80 size_t result_aligned = align_size_down(result, heap->old_gen_alignment());
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81 return result_aligned;
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82 }
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83
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84 size_t ASPSOldGen::available_for_contraction() {
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85 size_t uncommitted_bytes = virtual_space()->uncommitted_size();
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86 if (uncommitted_bytes != 0) {
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87 return uncommitted_bytes;
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88 }
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89
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90 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
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91 const size_t gen_alignment = heap->old_gen_alignment();
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92 PSAdaptiveSizePolicy* policy = heap->size_policy();
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93 const size_t working_size =
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94 used_in_bytes() + (size_t) policy->avg_promoted()->padded_average();
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95 const size_t working_aligned = align_size_up(working_size, gen_alignment);
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96 const size_t working_or_min = MAX2(working_aligned, min_gen_size());
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97 if (working_or_min > reserved().byte_size()) {
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98 // If the used or minimum gen size (aligned up) is greater
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99 // than the total reserved size, then the space available
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100 // for contraction should (after proper alignment) be 0
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101 return 0;
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102 }
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103 const size_t max_contraction =
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104 reserved().byte_size() - working_or_min;
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105
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106 // Use the "increment" fraction instead of the "decrement" fraction
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107 // to allow the other gen to expand more aggressively. The
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108 // "decrement" fraction is conservative because its intent is to
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109 // only reduce the footprint.
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110
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111 size_t result = policy->promo_increment_aligned_down(max_contraction);
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112 // Also adjust for inter-generational alignment
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113 size_t result_aligned = align_size_down(result, gen_alignment);
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114 if (PrintAdaptiveSizePolicy && Verbose) {
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115 gclog_or_tty->print_cr("\nASPSOldGen::available_for_contraction:"
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116 " %d K / 0x%x", result_aligned/K, result_aligned);
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117 gclog_or_tty->print_cr(" reserved().byte_size() %d K / 0x%x ",
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118 reserved().byte_size()/K, reserved().byte_size());
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119 size_t working_promoted = (size_t) policy->avg_promoted()->padded_average();
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120 gclog_or_tty->print_cr(" padded promoted %d K / 0x%x",
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121 working_promoted/K, working_promoted);
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122 gclog_or_tty->print_cr(" used %d K / 0x%x",
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123 used_in_bytes()/K, used_in_bytes());
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124 gclog_or_tty->print_cr(" min_gen_size() %d K / 0x%x",
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125 min_gen_size()/K, min_gen_size());
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126 gclog_or_tty->print_cr(" max_contraction %d K / 0x%x",
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127 max_contraction/K, max_contraction);
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128 gclog_or_tty->print_cr(" without alignment %d K / 0x%x",
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129 policy->promo_increment(max_contraction)/K,
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130 policy->promo_increment(max_contraction));
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131 gclog_or_tty->print_cr(" alignment 0x%x", gen_alignment);
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132 }
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133 assert(result_aligned <= max_contraction, "arithmetic is wrong");
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134 return result_aligned;
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135 }