1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/gc_implementation/parNew/parGCAllocBuffer.hpp Sat Dec 01 00:00:00 2007 +0000
1.3 @@ -0,0 +1,241 @@
1.4 +/*
1.5 + * Copyright 2001-2006 Sun Microsystems, Inc. All Rights Reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
1.23 + * CA 95054 USA or visit www.sun.com if you need additional information or
1.24 + * have any questions.
1.25 + *
1.26 + */
1.27 +
1.28 +// Forward decl.
1.29 +
1.30 +class PLABStats;
1.31 +
1.32 +// A per-thread allocation buffer used during GC.
1.33 +class ParGCAllocBuffer: public CHeapObj {
1.34 +protected:
1.35 + char head[32];
1.36 + size_t _word_sz; // in HeapWord units
1.37 + HeapWord* _bottom;
1.38 + HeapWord* _top;
1.39 + HeapWord* _end; // last allocatable address + 1
1.40 + HeapWord* _hard_end; // _end + AlignmentReserve
1.41 + bool _retained; // whether we hold a _retained_filler
1.42 + MemRegion _retained_filler;
1.43 + // In support of ergonomic sizing of PLAB's
1.44 + size_t _allocated; // in HeapWord units
1.45 + size_t _wasted; // in HeapWord units
1.46 + char tail[32];
1.47 + static const size_t FillerHeaderSize;
1.48 + static const size_t AlignmentReserve;
1.49 +
1.50 +public:
1.51 + // Initializes the buffer to be empty, but with the given "word_sz".
1.52 + // Must get initialized with "set_buf" for an allocation to succeed.
1.53 + ParGCAllocBuffer(size_t word_sz);
1.54 +
1.55 + static const size_t min_size() {
1.56 + return ThreadLocalAllocBuffer::min_size();
1.57 + }
1.58 +
1.59 + static const size_t max_size() {
1.60 + return ThreadLocalAllocBuffer::max_size();
1.61 + }
1.62 +
1.63 + // If an allocation of the given "word_sz" can be satisfied within the
1.64 + // buffer, do the allocation, returning a pointer to the start of the
1.65 + // allocated block. If the allocation request cannot be satisfied,
1.66 + // return NULL.
1.67 + HeapWord* allocate(size_t word_sz) {
1.68 + HeapWord* res = _top;
1.69 + HeapWord* new_top = _top + word_sz;
1.70 + if (new_top <= _end) {
1.71 + _top = new_top;
1.72 + return res;
1.73 + } else {
1.74 + return NULL;
1.75 + }
1.76 + }
1.77 +
1.78 + // Undo the last allocation in the buffer, which is required to be of the
1.79 + // "obj" of the given "word_sz".
1.80 + void undo_allocation(HeapWord* obj, size_t word_sz) {
1.81 + assert(_top - word_sz >= _bottom
1.82 + && _top - word_sz == obj,
1.83 + "Bad undo_allocation");
1.84 + _top = _top - word_sz;
1.85 + }
1.86 +
1.87 + // The total (word) size of the buffer, including both allocated and
1.88 + // unallocted space.
1.89 + size_t word_sz() { return _word_sz; }
1.90 +
1.91 + // Should only be done if we are about to reset with a new buffer of the
1.92 + // given size.
1.93 + void set_word_size(size_t new_word_sz) {
1.94 + assert(new_word_sz > AlignmentReserve, "Too small");
1.95 + _word_sz = new_word_sz;
1.96 + }
1.97 +
1.98 + // The number of words of unallocated space remaining in the buffer.
1.99 + size_t words_remaining() {
1.100 + assert(_end >= _top, "Negative buffer");
1.101 + return pointer_delta(_end, _top, HeapWordSize);
1.102 + }
1.103 +
1.104 + bool contains(void* addr) {
1.105 + return (void*)_bottom <= addr && addr < (void*)_hard_end;
1.106 + }
1.107 +
1.108 + // Sets the space of the buffer to be [buf, space+word_sz()).
1.109 + void set_buf(HeapWord* buf) {
1.110 + _bottom = buf;
1.111 + _top = _bottom;
1.112 + _hard_end = _bottom + word_sz();
1.113 + _end = _hard_end - AlignmentReserve;
1.114 + assert(_end >= _top, "Negative buffer");
1.115 + // In support of ergonomic sizing
1.116 + _allocated += word_sz();
1.117 + }
1.118 +
1.119 + // Flush the stats supporting ergonomic sizing of PLAB's
1.120 + void flush_stats(PLABStats* stats);
1.121 + void flush_stats_and_retire(PLABStats* stats, bool retain) {
1.122 + // We flush the stats first in order to get a reading of
1.123 + // unused space in the last buffer.
1.124 + if (ResizePLAB) {
1.125 + flush_stats(stats);
1.126 + }
1.127 + // Retire the last allocation buffer.
1.128 + retire(true, retain);
1.129 + }
1.130 +
1.131 + // Force future allocations to fail and queries for contains()
1.132 + // to return false
1.133 + void invalidate() {
1.134 + assert(!_retained, "Shouldn't retain an invalidated buffer.");
1.135 + _end = _hard_end;
1.136 + _wasted += pointer_delta(_end, _top); // unused space
1.137 + _top = _end; // force future allocations to fail
1.138 + _bottom = _end; // force future contains() queries to return false
1.139 + }
1.140 +
1.141 + // Fills in the unallocated portion of the buffer with a garbage object.
1.142 + // If "end_of_gc" is TRUE, is after the last use in the GC. IF "retain"
1.143 + // is true, attempt to re-use the unused portion in the next GC.
1.144 + void retire(bool end_of_gc, bool retain);
1.145 +
1.146 + void print() PRODUCT_RETURN;
1.147 +};
1.148 +
1.149 +// PLAB stats book-keeping
1.150 +class PLABStats VALUE_OBJ_CLASS_SPEC {
1.151 + size_t _allocated; // total allocated
1.152 + size_t _wasted; // of which wasted (internal fragmentation)
1.153 + size_t _unused; // Unused in last buffer
1.154 + size_t _used; // derived = allocated - wasted - unused
1.155 + size_t _desired_plab_sz;// output of filter (below), suitably trimmed and quantized
1.156 + AdaptiveWeightedAverage
1.157 + _filter; // integrator with decay
1.158 +
1.159 + public:
1.160 + PLABStats(size_t desired_plab_sz_, unsigned wt) :
1.161 + _allocated(0),
1.162 + _wasted(0),
1.163 + _unused(0),
1.164 + _used(0),
1.165 + _desired_plab_sz(desired_plab_sz_),
1.166 + _filter(wt)
1.167 + {
1.168 + size_t min_sz = min_size();
1.169 + size_t max_sz = max_size();
1.170 + size_t aligned_min_sz = align_object_size(min_sz);
1.171 + size_t aligned_max_sz = align_object_size(max_sz);
1.172 + assert(min_sz <= aligned_min_sz && max_sz >= aligned_max_sz &&
1.173 + min_sz <= max_sz,
1.174 + "PLAB clipping computation in adjust_desired_plab_sz()"
1.175 + " may be incorrect");
1.176 + }
1.177 +
1.178 + static const size_t min_size() {
1.179 + return ParGCAllocBuffer::min_size();
1.180 + }
1.181 +
1.182 + static const size_t max_size() {
1.183 + return ParGCAllocBuffer::max_size();
1.184 + }
1.185 +
1.186 + size_t desired_plab_sz() {
1.187 + return _desired_plab_sz;
1.188 + }
1.189 +
1.190 + void adjust_desired_plab_sz(); // filter computation, latches output to
1.191 + // _desired_plab_sz, clears sensor accumulators
1.192 +
1.193 + void add_allocated(size_t v) {
1.194 + Atomic::add_ptr(v, &_allocated);
1.195 + }
1.196 +
1.197 + void add_unused(size_t v) {
1.198 + Atomic::add_ptr(v, &_unused);
1.199 + }
1.200 +
1.201 + void add_wasted(size_t v) {
1.202 + Atomic::add_ptr(v, &_wasted);
1.203 + }
1.204 +};
1.205 +
1.206 +class ParGCAllocBufferWithBOT: public ParGCAllocBuffer {
1.207 + BlockOffsetArrayContigSpace _bt;
1.208 + BlockOffsetSharedArray* _bsa;
1.209 + HeapWord* _true_end; // end of the whole ParGCAllocBuffer
1.210 +
1.211 + static const size_t ChunkSizeInWords;
1.212 + static const size_t ChunkSizeInBytes;
1.213 + HeapWord* allocate_slow(size_t word_sz);
1.214 +
1.215 + void fill_region_with_block(MemRegion mr, bool contig);
1.216 +
1.217 +public:
1.218 + ParGCAllocBufferWithBOT(size_t word_sz, BlockOffsetSharedArray* bsa);
1.219 +
1.220 + HeapWord* allocate(size_t word_sz) {
1.221 + HeapWord* res = ParGCAllocBuffer::allocate(word_sz);
1.222 + if (res != NULL) {
1.223 + _bt.alloc_block(res, word_sz);
1.224 + } else {
1.225 + res = allocate_slow(word_sz);
1.226 + }
1.227 + return res;
1.228 + }
1.229 +
1.230 + void undo_allocation(HeapWord* obj, size_t word_sz);
1.231 +
1.232 + void set_buf(HeapWord* buf_start) {
1.233 + ParGCAllocBuffer::set_buf(buf_start);
1.234 + _true_end = _hard_end;
1.235 + _bt.set_region(MemRegion(buf_start, word_sz()));
1.236 + _bt.initialize_threshold();
1.237 + }
1.238 +
1.239 + void retire(bool end_of_gc, bool retain);
1.240 +
1.241 + MemRegion range() {
1.242 + return MemRegion(_top, _true_end);
1.243 + }
1.244 +};
