1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/gc_implementation/parNew/parCardTableModRefBS.cpp Sat Dec 01 00:00:00 2007 +0000
1.3 @@ -0,0 +1,315 @@
1.4 +/*
1.5 + * Copyright (c) 2007 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 +# include "incls/_precompiled.incl"
1.29 +# include "incls/_parCardTableModRefBS.cpp.incl"
1.30 +
1.31 +void CardTableModRefBS::par_non_clean_card_iterate_work(Space* sp, MemRegion mr,
1.32 + DirtyCardToOopClosure* dcto_cl,
1.33 + MemRegionClosure* cl,
1.34 + bool clear,
1.35 + int n_threads) {
1.36 + if (n_threads > 0) {
1.37 + assert(n_threads == (int)ParallelGCThreads, "# worker threads != # requested!");
1.38 +
1.39 + // Make sure the LNC array is valid for the space.
1.40 + jbyte** lowest_non_clean;
1.41 + uintptr_t lowest_non_clean_base_chunk_index;
1.42 + size_t lowest_non_clean_chunk_size;
1.43 + get_LNC_array_for_space(sp, lowest_non_clean,
1.44 + lowest_non_clean_base_chunk_index,
1.45 + lowest_non_clean_chunk_size);
1.46 +
1.47 + int n_strides = n_threads * StridesPerThread;
1.48 + SequentialSubTasksDone* pst = sp->par_seq_tasks();
1.49 + pst->set_par_threads(n_threads);
1.50 + pst->set_n_tasks(n_strides);
1.51 +
1.52 + int stride = 0;
1.53 + while (!pst->is_task_claimed(/* reference */ stride)) {
1.54 + process_stride(sp, mr, stride, n_strides, dcto_cl, cl, clear,
1.55 + lowest_non_clean,
1.56 + lowest_non_clean_base_chunk_index,
1.57 + lowest_non_clean_chunk_size);
1.58 + }
1.59 + if (pst->all_tasks_completed()) {
1.60 + // Clear lowest_non_clean array for next time.
1.61 + intptr_t first_chunk_index = addr_to_chunk_index(mr.start());
1.62 + uintptr_t last_chunk_index = addr_to_chunk_index(mr.last());
1.63 + for (uintptr_t ch = first_chunk_index; ch <= last_chunk_index; ch++) {
1.64 + intptr_t ind = ch - lowest_non_clean_base_chunk_index;
1.65 + assert(0 <= ind && ind < (intptr_t)lowest_non_clean_chunk_size,
1.66 + "Bounds error");
1.67 + lowest_non_clean[ind] = NULL;
1.68 + }
1.69 + }
1.70 + }
1.71 +}
1.72 +
1.73 +void
1.74 +CardTableModRefBS::
1.75 +process_stride(Space* sp,
1.76 + MemRegion used,
1.77 + jint stride, int n_strides,
1.78 + DirtyCardToOopClosure* dcto_cl,
1.79 + MemRegionClosure* cl,
1.80 + bool clear,
1.81 + jbyte** lowest_non_clean,
1.82 + uintptr_t lowest_non_clean_base_chunk_index,
1.83 + size_t lowest_non_clean_chunk_size) {
1.84 + // We don't have to go downwards here; it wouldn't help anyway,
1.85 + // because of parallelism.
1.86 +
1.87 + // Find the first card address of the first chunk in the stride that is
1.88 + // at least "bottom" of the used region.
1.89 + jbyte* start_card = byte_for(used.start());
1.90 + jbyte* end_card = byte_after(used.last());
1.91 + uintptr_t start_chunk = addr_to_chunk_index(used.start());
1.92 + uintptr_t start_chunk_stride_num = start_chunk % n_strides;
1.93 + jbyte* chunk_card_start;
1.94 +
1.95 + if ((uintptr_t)stride >= start_chunk_stride_num) {
1.96 + chunk_card_start = (jbyte*)(start_card +
1.97 + (stride - start_chunk_stride_num) *
1.98 + CardsPerStrideChunk);
1.99 + } else {
1.100 + // Go ahead to the next chunk group boundary, then to the requested stride.
1.101 + chunk_card_start = (jbyte*)(start_card +
1.102 + (n_strides - start_chunk_stride_num + stride) *
1.103 + CardsPerStrideChunk);
1.104 + }
1.105 +
1.106 + while (chunk_card_start < end_card) {
1.107 + // We don't have to go downwards here; it wouldn't help anyway,
1.108 + // because of parallelism. (We take care with "min_done"; see below.)
1.109 + // Invariant: chunk_mr should be fully contained within the "used" region.
1.110 + jbyte* chunk_card_end = chunk_card_start + CardsPerStrideChunk;
1.111 + MemRegion chunk_mr = MemRegion(addr_for(chunk_card_start),
1.112 + chunk_card_end >= end_card ?
1.113 + used.end() : addr_for(chunk_card_end));
1.114 + assert(chunk_mr.word_size() > 0, "[chunk_card_start > used_end)");
1.115 + assert(used.contains(chunk_mr), "chunk_mr should be subset of used");
1.116 +
1.117 + // Process the chunk.
1.118 + process_chunk_boundaries(sp,
1.119 + dcto_cl,
1.120 + chunk_mr,
1.121 + used,
1.122 + lowest_non_clean,
1.123 + lowest_non_clean_base_chunk_index,
1.124 + lowest_non_clean_chunk_size);
1.125 +
1.126 + non_clean_card_iterate_work(chunk_mr, cl, clear);
1.127 +
1.128 + // Find the next chunk of the stride.
1.129 + chunk_card_start += CardsPerStrideChunk * n_strides;
1.130 + }
1.131 +}
1.132 +
1.133 +void
1.134 +CardTableModRefBS::
1.135 +process_chunk_boundaries(Space* sp,
1.136 + DirtyCardToOopClosure* dcto_cl,
1.137 + MemRegion chunk_mr,
1.138 + MemRegion used,
1.139 + jbyte** lowest_non_clean,
1.140 + uintptr_t lowest_non_clean_base_chunk_index,
1.141 + size_t lowest_non_clean_chunk_size)
1.142 +{
1.143 + // We must worry about the chunk boundaries.
1.144 +
1.145 + // First, set our max_to_do:
1.146 + HeapWord* max_to_do = NULL;
1.147 + uintptr_t cur_chunk_index = addr_to_chunk_index(chunk_mr.start());
1.148 + cur_chunk_index = cur_chunk_index - lowest_non_clean_base_chunk_index;
1.149 +
1.150 + if (chunk_mr.end() < used.end()) {
1.151 + // This is not the last chunk in the used region. What is the last
1.152 + // object?
1.153 + HeapWord* last_block = sp->block_start(chunk_mr.end());
1.154 + assert(last_block <= chunk_mr.end(), "In case this property changes.");
1.155 + if (last_block == chunk_mr.end()
1.156 + || !sp->block_is_obj(last_block)) {
1.157 + max_to_do = chunk_mr.end();
1.158 +
1.159 + } else {
1.160 + // It is an object and starts before the end of the current chunk.
1.161 + // last_obj_card is the card corresponding to the start of the last object
1.162 + // in the chunk. Note that the last object may not start in
1.163 + // the chunk.
1.164 + jbyte* last_obj_card = byte_for(last_block);
1.165 + if (!card_may_have_been_dirty(*last_obj_card)) {
1.166 + // The card containing the head is not dirty. Any marks in
1.167 + // subsequent cards still in this chunk must have been made
1.168 + // precisely; we can cap processing at the end.
1.169 + max_to_do = chunk_mr.end();
1.170 + } else {
1.171 + // The last object must be considered dirty, and extends onto the
1.172 + // following chunk. Look for a dirty card in that chunk that will
1.173 + // bound our processing.
1.174 + jbyte* limit_card = NULL;
1.175 + size_t last_block_size = sp->block_size(last_block);
1.176 + jbyte* last_card_of_last_obj =
1.177 + byte_for(last_block + last_block_size - 1);
1.178 + jbyte* first_card_of_next_chunk = byte_for(chunk_mr.end());
1.179 + // This search potentially goes a long distance looking
1.180 + // for the next card that will be scanned. For example,
1.181 + // an object that is an array of primitives will not
1.182 + // have any cards covering regions interior to the array
1.183 + // that will need to be scanned. The scan can be terminated
1.184 + // at the last card of the next chunk. That would leave
1.185 + // limit_card as NULL and would result in "max_to_do"
1.186 + // being set with the LNC value or with the end
1.187 + // of the last block.
1.188 + jbyte* last_card_of_next_chunk = first_card_of_next_chunk +
1.189 + CardsPerStrideChunk;
1.190 + assert(byte_for(chunk_mr.end()) - byte_for(chunk_mr.start())
1.191 + == CardsPerStrideChunk, "last card of next chunk may be wrong");
1.192 + jbyte* last_card_to_check = (jbyte*) MIN2(last_card_of_last_obj,
1.193 + last_card_of_next_chunk);
1.194 + for (jbyte* cur = first_card_of_next_chunk;
1.195 + cur <= last_card_to_check; cur++) {
1.196 + if (card_will_be_scanned(*cur)) {
1.197 + limit_card = cur; break;
1.198 + }
1.199 + }
1.200 + assert(0 <= cur_chunk_index+1 &&
1.201 + cur_chunk_index+1 < lowest_non_clean_chunk_size,
1.202 + "Bounds error.");
1.203 + // LNC for the next chunk
1.204 + jbyte* lnc_card = lowest_non_clean[cur_chunk_index+1];
1.205 + if (limit_card == NULL) {
1.206 + limit_card = lnc_card;
1.207 + }
1.208 + if (limit_card != NULL) {
1.209 + if (lnc_card != NULL) {
1.210 + limit_card = (jbyte*)MIN2((intptr_t)limit_card,
1.211 + (intptr_t)lnc_card);
1.212 + }
1.213 + max_to_do = addr_for(limit_card);
1.214 + } else {
1.215 + max_to_do = last_block + last_block_size;
1.216 + }
1.217 + }
1.218 + }
1.219 + assert(max_to_do != NULL, "OOPS!");
1.220 + } else {
1.221 + max_to_do = used.end();
1.222 + }
1.223 + // Now we can set the closure we're using so it doesn't to beyond
1.224 + // max_to_do.
1.225 + dcto_cl->set_min_done(max_to_do);
1.226 +#ifndef PRODUCT
1.227 + dcto_cl->set_last_bottom(max_to_do);
1.228 +#endif
1.229 +
1.230 + // Now we set *our" lowest_non_clean entry.
1.231 + // Find the object that spans our boundary, if one exists.
1.232 + // Nothing to do on the first chunk.
1.233 + if (chunk_mr.start() > used.start()) {
1.234 + // first_block is the block possibly spanning the chunk start
1.235 + HeapWord* first_block = sp->block_start(chunk_mr.start());
1.236 + // Does the block span the start of the chunk and is it
1.237 + // an object?
1.238 + if (first_block < chunk_mr.start() &&
1.239 + sp->block_is_obj(first_block)) {
1.240 + jbyte* first_dirty_card = NULL;
1.241 + jbyte* last_card_of_first_obj =
1.242 + byte_for(first_block + sp->block_size(first_block) - 1);
1.243 + jbyte* first_card_of_cur_chunk = byte_for(chunk_mr.start());
1.244 + jbyte* last_card_of_cur_chunk = byte_for(chunk_mr.last());
1.245 + jbyte* last_card_to_check =
1.246 + (jbyte*) MIN2((intptr_t) last_card_of_cur_chunk,
1.247 + (intptr_t) last_card_of_first_obj);
1.248 + for (jbyte* cur = first_card_of_cur_chunk;
1.249 + cur <= last_card_to_check; cur++) {
1.250 + if (card_will_be_scanned(*cur)) {
1.251 + first_dirty_card = cur; break;
1.252 + }
1.253 + }
1.254 + if (first_dirty_card != NULL) {
1.255 + assert(0 <= cur_chunk_index &&
1.256 + cur_chunk_index < lowest_non_clean_chunk_size,
1.257 + "Bounds error.");
1.258 + lowest_non_clean[cur_chunk_index] = first_dirty_card;
1.259 + }
1.260 + }
1.261 + }
1.262 +}
1.263 +
1.264 +void
1.265 +CardTableModRefBS::
1.266 +get_LNC_array_for_space(Space* sp,
1.267 + jbyte**& lowest_non_clean,
1.268 + uintptr_t& lowest_non_clean_base_chunk_index,
1.269 + size_t& lowest_non_clean_chunk_size) {
1.270 +
1.271 + int i = find_covering_region_containing(sp->bottom());
1.272 + MemRegion covered = _covered[i];
1.273 + size_t n_chunks = chunks_to_cover(covered);
1.274 +
1.275 + // Only the first thread to obtain the lock will resize the
1.276 + // LNC array for the covered region. Any later expansion can't affect
1.277 + // the used_at_save_marks region.
1.278 + // (I observed a bug in which the first thread to execute this would
1.279 + // resize, and then it would cause "expand_and_allocates" that would
1.280 + // Increase the number of chunks in the covered region. Then a second
1.281 + // thread would come and execute this, see that the size didn't match,
1.282 + // and free and allocate again. So the first thread would be using a
1.283 + // freed "_lowest_non_clean" array.)
1.284 +
1.285 + // Do a dirty read here. If we pass the conditional then take the rare
1.286 + // event lock and do the read again in case some other thread had already
1.287 + // succeeded and done the resize.
1.288 + int cur_collection = Universe::heap()->total_collections();
1.289 + if (_last_LNC_resizing_collection[i] != cur_collection) {
1.290 + MutexLocker x(ParGCRareEvent_lock);
1.291 + if (_last_LNC_resizing_collection[i] != cur_collection) {
1.292 + if (_lowest_non_clean[i] == NULL ||
1.293 + n_chunks != _lowest_non_clean_chunk_size[i]) {
1.294 +
1.295 + // Should we delete the old?
1.296 + if (_lowest_non_clean[i] != NULL) {
1.297 + assert(n_chunks != _lowest_non_clean_chunk_size[i],
1.298 + "logical consequence");
1.299 + FREE_C_HEAP_ARRAY(CardPtr, _lowest_non_clean[i]);
1.300 + _lowest_non_clean[i] = NULL;
1.301 + }
1.302 + // Now allocate a new one if necessary.
1.303 + if (_lowest_non_clean[i] == NULL) {
1.304 + _lowest_non_clean[i] = NEW_C_HEAP_ARRAY(CardPtr, n_chunks);
1.305 + _lowest_non_clean_chunk_size[i] = n_chunks;
1.306 + _lowest_non_clean_base_chunk_index[i] = addr_to_chunk_index(covered.start());
1.307 + for (int j = 0; j < (int)n_chunks; j++)
1.308 + _lowest_non_clean[i][j] = NULL;
1.309 + }
1.310 + }
1.311 + _last_LNC_resizing_collection[i] = cur_collection;
1.312 + }
1.313 + }
1.314 + // In any case, now do the initialization.
1.315 + lowest_non_clean = _lowest_non_clean[i];
1.316 + lowest_non_clean_base_chunk_index = _lowest_non_clean_base_chunk_index[i];
1.317 + lowest_non_clean_chunk_size = _lowest_non_clean_chunk_size[i];
1.318 +}
