--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc_implementation/parNew/parCardTableModRefBS.cpp Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,315 @@
+/*
+ * Copyright (c) 2007 Sun Microsystems, Inc. All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+# include "incls/_precompiled.incl"
+# include "incls/_parCardTableModRefBS.cpp.incl"
+
+void CardTableModRefBS::par_non_clean_card_iterate_work(Space* sp, MemRegion mr,
+ DirtyCardToOopClosure* dcto_cl,
+ MemRegionClosure* cl,
+ bool clear,
+ int n_threads) {
+ if (n_threads > 0) {
+ assert(n_threads == (int)ParallelGCThreads, "# worker threads != # requested!");
+
+ // Make sure the LNC array is valid for the space.
+ jbyte** lowest_non_clean;
+ uintptr_t lowest_non_clean_base_chunk_index;
+ size_t lowest_non_clean_chunk_size;
+ get_LNC_array_for_space(sp, lowest_non_clean,
+ lowest_non_clean_base_chunk_index,
+ lowest_non_clean_chunk_size);
+
+ int n_strides = n_threads * StridesPerThread;
+ SequentialSubTasksDone* pst = sp->par_seq_tasks();
+ pst->set_par_threads(n_threads);
+ pst->set_n_tasks(n_strides);
+
+ int stride = 0;
+ while (!pst->is_task_claimed(/* reference */ stride)) {
+ process_stride(sp, mr, stride, n_strides, dcto_cl, cl, clear,
+ lowest_non_clean,
+ lowest_non_clean_base_chunk_index,
+ lowest_non_clean_chunk_size);
+ }
+ if (pst->all_tasks_completed()) {
+ // Clear lowest_non_clean array for next time.
+ intptr_t first_chunk_index = addr_to_chunk_index(mr.start());
+ uintptr_t last_chunk_index = addr_to_chunk_index(mr.last());
+ for (uintptr_t ch = first_chunk_index; ch <= last_chunk_index; ch++) {
+ intptr_t ind = ch - lowest_non_clean_base_chunk_index;
+ assert(0 <= ind && ind < (intptr_t)lowest_non_clean_chunk_size,
+ "Bounds error");
+ lowest_non_clean[ind] = NULL;
+ }
+ }
+ }
+}
+
+void
+CardTableModRefBS::
+process_stride(Space* sp,
+ MemRegion used,
+ jint stride, int n_strides,
+ DirtyCardToOopClosure* dcto_cl,
+ MemRegionClosure* cl,
+ bool clear,
+ jbyte** lowest_non_clean,
+ uintptr_t lowest_non_clean_base_chunk_index,
+ size_t lowest_non_clean_chunk_size) {
+ // We don't have to go downwards here; it wouldn't help anyway,
+ // because of parallelism.
+
+ // Find the first card address of the first chunk in the stride that is
+ // at least "bottom" of the used region.
+ jbyte* start_card = byte_for(used.start());
+ jbyte* end_card = byte_after(used.last());
+ uintptr_t start_chunk = addr_to_chunk_index(used.start());
+ uintptr_t start_chunk_stride_num = start_chunk % n_strides;
+ jbyte* chunk_card_start;
+
+ if ((uintptr_t)stride >= start_chunk_stride_num) {
+ chunk_card_start = (jbyte*)(start_card +
+ (stride - start_chunk_stride_num) *
+ CardsPerStrideChunk);
+ } else {
+ // Go ahead to the next chunk group boundary, then to the requested stride.
+ chunk_card_start = (jbyte*)(start_card +
+ (n_strides - start_chunk_stride_num + stride) *
+ CardsPerStrideChunk);
+ }
+
+ while (chunk_card_start < end_card) {
+ // We don't have to go downwards here; it wouldn't help anyway,
+ // because of parallelism. (We take care with "min_done"; see below.)
+ // Invariant: chunk_mr should be fully contained within the "used" region.
+ jbyte* chunk_card_end = chunk_card_start + CardsPerStrideChunk;
+ MemRegion chunk_mr = MemRegion(addr_for(chunk_card_start),
+ chunk_card_end >= end_card ?
+ used.end() : addr_for(chunk_card_end));
+ assert(chunk_mr.word_size() > 0, "[chunk_card_start > used_end)");
+ assert(used.contains(chunk_mr), "chunk_mr should be subset of used");
+
+ // Process the chunk.
+ process_chunk_boundaries(sp,
+ dcto_cl,
+ chunk_mr,
+ used,
+ lowest_non_clean,
+ lowest_non_clean_base_chunk_index,
+ lowest_non_clean_chunk_size);
+
+ non_clean_card_iterate_work(chunk_mr, cl, clear);
+
+ // Find the next chunk of the stride.
+ chunk_card_start += CardsPerStrideChunk * n_strides;
+ }
+}
+
+void
+CardTableModRefBS::
+process_chunk_boundaries(Space* sp,
+ DirtyCardToOopClosure* dcto_cl,
+ MemRegion chunk_mr,
+ MemRegion used,
+ jbyte** lowest_non_clean,
+ uintptr_t lowest_non_clean_base_chunk_index,
+ size_t lowest_non_clean_chunk_size)
+{
+ // We must worry about the chunk boundaries.
+
+ // First, set our max_to_do:
+ HeapWord* max_to_do = NULL;
+ uintptr_t cur_chunk_index = addr_to_chunk_index(chunk_mr.start());
+ cur_chunk_index = cur_chunk_index - lowest_non_clean_base_chunk_index;
+
+ if (chunk_mr.end() < used.end()) {
+ // This is not the last chunk in the used region. What is the last
+ // object?
+ HeapWord* last_block = sp->block_start(chunk_mr.end());
+ assert(last_block <= chunk_mr.end(), "In case this property changes.");
+ if (last_block == chunk_mr.end()
+ || !sp->block_is_obj(last_block)) {
+ max_to_do = chunk_mr.end();
+
+ } else {
+ // It is an object and starts before the end of the current chunk.
+ // last_obj_card is the card corresponding to the start of the last object
+ // in the chunk. Note that the last object may not start in
+ // the chunk.
+ jbyte* last_obj_card = byte_for(last_block);
+ if (!card_may_have_been_dirty(*last_obj_card)) {
+ // The card containing the head is not dirty. Any marks in
+ // subsequent cards still in this chunk must have been made
+ // precisely; we can cap processing at the end.
+ max_to_do = chunk_mr.end();
+ } else {
+ // The last object must be considered dirty, and extends onto the
+ // following chunk. Look for a dirty card in that chunk that will
+ // bound our processing.
+ jbyte* limit_card = NULL;
+ size_t last_block_size = sp->block_size(last_block);
+ jbyte* last_card_of_last_obj =
+ byte_for(last_block + last_block_size - 1);
+ jbyte* first_card_of_next_chunk = byte_for(chunk_mr.end());
+ // This search potentially goes a long distance looking
+ // for the next card that will be scanned. For example,
+ // an object that is an array of primitives will not
+ // have any cards covering regions interior to the array
+ // that will need to be scanned. The scan can be terminated
+ // at the last card of the next chunk. That would leave
+ // limit_card as NULL and would result in "max_to_do"
+ // being set with the LNC value or with the end
+ // of the last block.
+ jbyte* last_card_of_next_chunk = first_card_of_next_chunk +
+ CardsPerStrideChunk;
+ assert(byte_for(chunk_mr.end()) - byte_for(chunk_mr.start())
+ == CardsPerStrideChunk, "last card of next chunk may be wrong");
+ jbyte* last_card_to_check = (jbyte*) MIN2(last_card_of_last_obj,
+ last_card_of_next_chunk);
+ for (jbyte* cur = first_card_of_next_chunk;
+ cur <= last_card_to_check; cur++) {
+ if (card_will_be_scanned(*cur)) {
+ limit_card = cur; break;
+ }
+ }
+ assert(0 <= cur_chunk_index+1 &&
+ cur_chunk_index+1 < lowest_non_clean_chunk_size,
+ "Bounds error.");
+ // LNC for the next chunk
+ jbyte* lnc_card = lowest_non_clean[cur_chunk_index+1];
+ if (limit_card == NULL) {
+ limit_card = lnc_card;
+ }
+ if (limit_card != NULL) {
+ if (lnc_card != NULL) {
+ limit_card = (jbyte*)MIN2((intptr_t)limit_card,
+ (intptr_t)lnc_card);
+ }
+ max_to_do = addr_for(limit_card);
+ } else {
+ max_to_do = last_block + last_block_size;
+ }
+ }
+ }
+ assert(max_to_do != NULL, "OOPS!");
+ } else {
+ max_to_do = used.end();
+ }
+ // Now we can set the closure we're using so it doesn't to beyond
+ // max_to_do.
+ dcto_cl->set_min_done(max_to_do);
+#ifndef PRODUCT
+ dcto_cl->set_last_bottom(max_to_do);
+#endif
+
+ // Now we set *our" lowest_non_clean entry.
+ // Find the object that spans our boundary, if one exists.
+ // Nothing to do on the first chunk.
+ if (chunk_mr.start() > used.start()) {
+ // first_block is the block possibly spanning the chunk start
+ HeapWord* first_block = sp->block_start(chunk_mr.start());
+ // Does the block span the start of the chunk and is it
+ // an object?
+ if (first_block < chunk_mr.start() &&
+ sp->block_is_obj(first_block)) {
+ jbyte* first_dirty_card = NULL;
+ jbyte* last_card_of_first_obj =
+ byte_for(first_block + sp->block_size(first_block) - 1);
+ jbyte* first_card_of_cur_chunk = byte_for(chunk_mr.start());
+ jbyte* last_card_of_cur_chunk = byte_for(chunk_mr.last());
+ jbyte* last_card_to_check =
+ (jbyte*) MIN2((intptr_t) last_card_of_cur_chunk,
+ (intptr_t) last_card_of_first_obj);
+ for (jbyte* cur = first_card_of_cur_chunk;
+ cur <= last_card_to_check; cur++) {
+ if (card_will_be_scanned(*cur)) {
+ first_dirty_card = cur; break;
+ }
+ }
+ if (first_dirty_card != NULL) {
+ assert(0 <= cur_chunk_index &&
+ cur_chunk_index < lowest_non_clean_chunk_size,
+ "Bounds error.");
+ lowest_non_clean[cur_chunk_index] = first_dirty_card;
+ }
+ }
+ }
+}
+
+void
+CardTableModRefBS::
+get_LNC_array_for_space(Space* sp,
+ jbyte**& lowest_non_clean,
+ uintptr_t& lowest_non_clean_base_chunk_index,
+ size_t& lowest_non_clean_chunk_size) {
+
+ int i = find_covering_region_containing(sp->bottom());
+ MemRegion covered = _covered[i];
+ size_t n_chunks = chunks_to_cover(covered);
+
+ // Only the first thread to obtain the lock will resize the
+ // LNC array for the covered region. Any later expansion can't affect
+ // the used_at_save_marks region.
+ // (I observed a bug in which the first thread to execute this would
+ // resize, and then it would cause "expand_and_allocates" that would
+ // Increase the number of chunks in the covered region. Then a second
+ // thread would come and execute this, see that the size didn't match,
+ // and free and allocate again. So the first thread would be using a
+ // freed "_lowest_non_clean" array.)
+
+ // Do a dirty read here. If we pass the conditional then take the rare
+ // event lock and do the read again in case some other thread had already
+ // succeeded and done the resize.
+ int cur_collection = Universe::heap()->total_collections();
+ if (_last_LNC_resizing_collection[i] != cur_collection) {
+ MutexLocker x(ParGCRareEvent_lock);
+ if (_last_LNC_resizing_collection[i] != cur_collection) {
+ if (_lowest_non_clean[i] == NULL ||
+ n_chunks != _lowest_non_clean_chunk_size[i]) {
+
+ // Should we delete the old?
+ if (_lowest_non_clean[i] != NULL) {
+ assert(n_chunks != _lowest_non_clean_chunk_size[i],
+ "logical consequence");
+ FREE_C_HEAP_ARRAY(CardPtr, _lowest_non_clean[i]);
+ _lowest_non_clean[i] = NULL;
+ }
+ // Now allocate a new one if necessary.
+ if (_lowest_non_clean[i] == NULL) {
+ _lowest_non_clean[i] = NEW_C_HEAP_ARRAY(CardPtr, n_chunks);
+ _lowest_non_clean_chunk_size[i] = n_chunks;
+ _lowest_non_clean_base_chunk_index[i] = addr_to_chunk_index(covered.start());
+ for (int j = 0; j < (int)n_chunks; j++)
+ _lowest_non_clean[i][j] = NULL;
+ }
+ }
+ _last_LNC_resizing_collection[i] = cur_collection;
+ }
+ }
+ // In any case, now do the initialization.
+ lowest_non_clean = _lowest_non_clean[i];
+ lowest_non_clean_base_chunk_index = _lowest_non_clean_base_chunk_index[i];
+ lowest_non_clean_chunk_size = _lowest_non_clean_chunk_size[i];
+}