1 /*
2 * Copyright (c) 2001, 2014, 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 #include "precompiled.hpp"
26 #include "gc_implementation/shared/parGCAllocBuffer.hpp"
27 #include "memory/sharedHeap.hpp"
28 #include "oops/arrayOop.hpp"
29 #include "oops/oop.inline.hpp"
30 #include "utilities/globalDefinitions.hpp"
31
32 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
33
34 ParGCAllocBuffer::ParGCAllocBuffer(size_t desired_plab_sz_) :
35 _word_sz(desired_plab_sz_), _bottom(NULL), _top(NULL),
36 _end(NULL), _hard_end(NULL),
37 _retained(false), _retained_filler(),
38 _allocated(0), _wasted(0)
39 {
40 assert (min_size() > AlignmentReserve, "Inconsistency!");
41 // arrayOopDesc::header_size depends on command line initialization.
42 FillerHeaderSize = align_object_size(arrayOopDesc::header_size(T_INT));
43 AlignmentReserve = oopDesc::header_size() > MinObjAlignment ? FillerHeaderSize : 0;
44 }
45
46 size_t ParGCAllocBuffer::FillerHeaderSize;
47
48 // If the minimum object size is greater than MinObjAlignment, we can
49 // end up with a shard at the end of the buffer that's smaller than
50 // the smallest object. We can't allow that because the buffer must
51 // look like it's full of objects when we retire it, so we make
52 // sure we have enough space for a filler int array object.
53 size_t ParGCAllocBuffer::AlignmentReserve;
54
55 void ParGCAllocBuffer::retire(bool end_of_gc, bool retain) {
56 assert(!retain || end_of_gc, "Can only retain at GC end.");
57 if (_retained) {
58 // If the buffer had been retained shorten the previous filler object.
59 assert(_retained_filler.end() <= _top, "INVARIANT");
60 CollectedHeap::fill_with_object(_retained_filler);
61 // Wasted space book-keeping, otherwise (normally) done in invalidate()
62 _wasted += _retained_filler.word_size();
63 _retained = false;
64 }
65 assert(!end_of_gc || !_retained, "At this point, end_of_gc ==> !_retained.");
66 if (_top < _hard_end) {
67 CollectedHeap::fill_with_object(_top, _hard_end);
68 if (!retain) {
69 invalidate();
70 } else {
71 // Is there wasted space we'd like to retain for the next GC?
72 if (pointer_delta(_end, _top) > FillerHeaderSize) {
73 _retained = true;
74 _retained_filler = MemRegion(_top, FillerHeaderSize);
75 _top = _top + FillerHeaderSize;
76 } else {
77 invalidate();
78 }
79 }
80 }
81 }
82
83 void ParGCAllocBuffer::flush_stats(PLABStats* stats) {
84 assert(ResizePLAB, "Wasted work");
85 stats->add_allocated(_allocated);
86 stats->add_wasted(_wasted);
87 stats->add_unused(pointer_delta(_end, _top));
88 }
89
90 // Compute desired plab size and latch result for later
91 // use. This should be called once at the end of parallel
92 // scavenge; it clears the sensor accumulators.
93 void PLABStats::adjust_desired_plab_sz(uint no_of_gc_workers) {
94 assert(ResizePLAB, "Not set");
95
96 assert(is_object_aligned(max_size()) && min_size() <= max_size(),
97 "PLAB clipping computation may be incorrect");
98
99 if (_allocated == 0) {
100 assert(_unused == 0,
101 err_msg("Inconsistency in PLAB stats: "
102 "_allocated: "SIZE_FORMAT", "
103 "_wasted: "SIZE_FORMAT", "
104 "_unused: "SIZE_FORMAT", "
105 "_used : "SIZE_FORMAT,
106 _allocated, _wasted, _unused, _used));
107
108 _allocated = 1;
109 }
110 double wasted_frac = (double)_unused/(double)_allocated;
111 size_t target_refills = (size_t)((wasted_frac*TargetSurvivorRatio)/
112 TargetPLABWastePct);
113 if (target_refills == 0) {
114 target_refills = 1;
115 }
116 _used = _allocated - _wasted - _unused;
117 size_t plab_sz = _used/(target_refills*no_of_gc_workers);
118 if (PrintPLAB) gclog_or_tty->print(" (plab_sz = " SIZE_FORMAT " ", plab_sz);
119 // Take historical weighted average
120 _filter.sample(plab_sz);
121 // Clip from above and below, and align to object boundary
122 plab_sz = MAX2(min_size(), (size_t)_filter.average());
123 plab_sz = MIN2(max_size(), plab_sz);
124 plab_sz = align_object_size(plab_sz);
125 // Latch the result
126 if (PrintPLAB) gclog_or_tty->print(" desired_plab_sz = " SIZE_FORMAT ") ", plab_sz);
127 _desired_plab_sz = plab_sz;
128 // Now clear the accumulators for next round:
129 // note this needs to be fixed in the case where we
130 // are retaining across scavenges. FIX ME !!! XXX
131 _allocated = 0;
132 _wasted = 0;
133 _unused = 0;
134 }
135
136 #ifndef PRODUCT
137 void ParGCAllocBuffer::print() {
138 gclog_or_tty->print("parGCAllocBuffer: _bottom: " PTR_FORMAT " _top: " PTR_FORMAT
139 " _end: " PTR_FORMAT " _hard_end: " PTR_FORMAT " _retained: %c"
140 " _retained_filler: [" PTR_FORMAT "," PTR_FORMAT ")\n",
141 _bottom, _top, _end, _hard_end,
142 "FT"[_retained], _retained_filler.start(), _retained_filler.end());
143 }
144 #endif // !PRODUCT
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1 /*
2 * Copyright (c) 2001, 2015, 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 #include "precompiled.hpp"
26 #include "gc_implementation/shared/parGCAllocBuffer.hpp"
27 #include "memory/threadLocalAllocBuffer.hpp"
28 #include "oops/arrayOop.hpp"
29 #include "oops/oop.inline.hpp"
30
31 size_t ParGCAllocBuffer::min_size() {
32 // Make sure that we return something that is larger than AlignmentReserve
33 return align_object_size(MAX2(MinTLABSize / HeapWordSize, (uintx)oopDesc::header_size())) + AlignmentReserve;
34 }
35
36 size_t ParGCAllocBuffer::max_size() {
37 return ThreadLocalAllocBuffer::max_size();
38 }
39
40 ParGCAllocBuffer::ParGCAllocBuffer(size_t desired_plab_sz_) :
41 _word_sz(desired_plab_sz_), _bottom(NULL), _top(NULL),
42 _end(NULL), _hard_end(NULL), _allocated(0), _wasted(0)
43 {
44 // ArrayOopDesc::header_size depends on command line initialization.
45 AlignmentReserve = oopDesc::header_size() > MinObjAlignment ? align_object_size(arrayOopDesc::header_size(T_INT)) : 0;
46 assert(min_size() > AlignmentReserve,
47 err_msg("Minimum PLAB size " SIZE_FORMAT" must be larger than alignment reserve " SIZE_FORMAT" "
48 "to be able to contain objects", min_size(), AlignmentReserve));
49 }
50
51 // If the minimum object size is greater than MinObjAlignment, we can
52 // end up with a shard at the end of the buffer that's smaller than
53 // the smallest object. We can't allow that because the buffer must
54 // look like it's full of objects when we retire it, so we make
55 // sure we have enough space for a filler int array object.
56 size_t ParGCAllocBuffer::AlignmentReserve;
57
58 void ParGCAllocBuffer::flush_and_retire_stats(PLABStats* stats) {
59 // We want to distinguish between unused space in the last buffer and waste
60 // created otherwise. Save the amount of unused space because retire() will
61 // update the pointers we use.
62 size_t unused = pointer_delta(_end, _top);
63
64 // Retire the last allocation buffer.
65 retire();
66
67 stats->add_allocated(_allocated);
68 // Retire() counts the unused space as wasted. So we need to remove it again
69 // before updating the statistics.
70 stats->add_wasted(_wasted - unused);
71 stats->add_unused(unused);
72
73 // Since we have flushed the stats we need to clear the _allocated and _wasted
74 // fields in case somebody retains an instance of this over GCs. Not doing so
75 // will artifically inflate the values in the statistics.
76 _allocated = 0;
77 _wasted = 0;
78 }
79
80 void ParGCAllocBuffer::retire() {
81 if (_top < _hard_end) {
82 CollectedHeap::fill_with_object(_top, _hard_end);
83 invalidate();
84 }
85 }
86
87 // Compute desired plab size and latch result for later
88 // use. This should be called once at the end of parallel
89 // scavenge; it clears the sensor accumulators.
90 void PLABStats::adjust_desired_plab_sz(uint no_of_gc_workers) {
91 assert(ResizePLAB, "Not set");
92
93 assert(is_object_aligned(max_size()) && min_size() <= max_size(),
94 "PLAB clipping computation may be incorrect");
95
96 if (_allocated == 0) {
97 assert(_unused == 0,
98 err_msg("Inconsistency in PLAB stats: "
99 "_allocated: "SIZE_FORMAT", "
100 "_wasted: "SIZE_FORMAT", "
101 "_unused: "SIZE_FORMAT,
102 _allocated, _wasted, _unused));
103
104 _allocated = 1;
105 }
106 double wasted_frac = (double)_unused / (double)_allocated;
107 size_t target_refills = (size_t)((wasted_frac * TargetSurvivorRatio) / TargetPLABWastePct);
108 if (target_refills == 0) {
109 target_refills = 1;
110 }
111 size_t used = _allocated - _wasted - _unused;
112 size_t recent_plab_sz = used / (target_refills * no_of_gc_workers);
113 // Take historical weighted average
114 _filter.sample(recent_plab_sz);
115 // Clip from above and below, and align to object boundary
116 size_t new_plab_sz = MAX2(min_size(), (size_t)_filter.average());
117 new_plab_sz = MIN2(max_size(), new_plab_sz);
118 new_plab_sz = align_object_size(new_plab_sz);
119 // Latch the result
120 if (PrintPLAB) {
121 gclog_or_tty->print(" (plab_sz = " SIZE_FORMAT" desired_plab_sz = " SIZE_FORMAT") ", recent_plab_sz, new_plab_sz);
122 }
123 _desired_plab_sz = new_plab_sz;
124
125 reset();
126 }
127
128 #ifndef PRODUCT
129 void ParGCAllocBuffer::print() {
130 gclog_or_tty->print_cr("parGCAllocBuffer: _bottom: " PTR_FORMAT " _top: " PTR_FORMAT
131 " _end: " PTR_FORMAT " _hard_end: " PTR_FORMAT ")",
132 p2i(_bottom), p2i(_top), p2i(_end), p2i(_hard_end));
133 }
134 #endif // !PRODUCT
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