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