1 /*
2 * Copyright (c) 2007, 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 *
178 DirtyCardToOopClosure* dcto_cl,
179 MemRegion chunk_mr,
180 MemRegion used,
181 jbyte** lowest_non_clean,
182 uintptr_t lowest_non_clean_base_chunk_index,
183 size_t lowest_non_clean_chunk_size)
184 {
185 // We must worry about non-array objects that cross chunk boundaries,
186 // because such objects are both precisely and imprecisely marked:
187 // .. if the head of such an object is dirty, the entire object
188 // needs to be scanned, under the interpretation that this
189 // was an imprecise mark
190 // .. if the head of such an object is not dirty, we can assume
191 // precise marking and it's efficient to scan just the dirty
192 // cards.
193 // In either case, each scanned reference must be scanned precisely
194 // once so as to avoid cloning of a young referent. For efficiency,
195 // our closures depend on this property and do not protect against
196 // double scans.
197
198 uintptr_t cur_chunk_index = addr_to_chunk_index(chunk_mr.start());
199 cur_chunk_index = cur_chunk_index - lowest_non_clean_base_chunk_index;
200
201 NOISY(tty->print_cr("===========================================================================");)
202 NOISY(tty->print_cr(" process_chunk_boundary: Called with [" PTR_FORMAT "," PTR_FORMAT ")",
203 chunk_mr.start(), chunk_mr.end());)
204
205 // First, set "our" lowest_non_clean entry, which would be
206 // used by the thread scanning an adjoining left chunk with
207 // a non-array object straddling the mutual boundary.
208 // Find the object that spans our boundary, if one exists.
209 // first_block is the block possibly straddling our left boundary.
210 HeapWord* first_block = sp->block_start(chunk_mr.start());
211 assert((chunk_mr.start() != used.start()) || (first_block == chunk_mr.start()),
212 "First chunk should always have a co-initial block");
213 // Does the block straddle the chunk's left boundary, and is it
214 // a non-array object?
215 if (first_block < chunk_mr.start() // first block straddles left bdry
216 && sp->block_is_obj(first_block) // first block is an object
217 && !(oop(first_block)->is_objArray() // first block is not an array (arrays are precisely dirtied)
218 || oop(first_block)->is_typeArray())) {
219 // Find our least non-clean card, so that a left neighbor
225 byte_for(first_block + sp->block_size(first_block) - 1);
226 jbyte* first_card_of_cur_chunk = byte_for(chunk_mr.start());
227 jbyte* last_card_of_cur_chunk = byte_for(chunk_mr.last());
228 jbyte* last_card_to_check =
229 (jbyte*) MIN2((intptr_t) last_card_of_cur_chunk,
230 (intptr_t) last_card_of_first_obj);
231 // Note that this does not need to go beyond our last card
232 // if our first object completely straddles this chunk.
233 for (jbyte* cur = first_card_of_cur_chunk;
234 cur <= last_card_to_check; cur++) {
235 jbyte val = *cur;
236 if (card_will_be_scanned(val)) {
237 first_dirty_card = cur; break;
238 } else {
239 assert(!card_may_have_been_dirty(val), "Error");
240 }
241 }
242 if (first_dirty_card != NULL) {
243 NOISY(tty->print_cr(" LNC: Found a dirty card at " PTR_FORMAT " in current chunk",
244 first_dirty_card);)
245 assert(0 <= cur_chunk_index && cur_chunk_index < lowest_non_clean_chunk_size,
246 "Bounds error.");
247 assert(lowest_non_clean[cur_chunk_index] == NULL,
248 "Write exactly once : value should be stable hereafter for this round");
249 lowest_non_clean[cur_chunk_index] = first_dirty_card;
250 } NOISY(else {
251 tty->print_cr(" LNC: Found no dirty card in current chunk; leaving LNC entry NULL");
252 // In the future, we could have this thread look for a non-NULL value to copy from its
253 // right neighbor (up to the end of the first object).
254 if (last_card_of_cur_chunk < last_card_of_first_obj) {
255 tty->print_cr(" LNC: BEWARE!!! first obj straddles past right end of chunk:\n"
256 " might be efficient to get value from right neighbor?");
257 }
258 })
259 } else {
260 // In this case we can help our neighbor by just asking them
261 // to stop at our first card (even though it may not be dirty).
262 NOISY(tty->print_cr(" LNC: first block is not a non-array object; setting LNC to first card of current chunk");)
263 assert(lowest_non_clean[cur_chunk_index] == NULL, "Write once : value should be stable hereafter");
264 jbyte* first_card_of_cur_chunk = byte_for(chunk_mr.start());
265 lowest_non_clean[cur_chunk_index] = first_card_of_cur_chunk;
|
1 /*
2 * Copyright (c) 2007, 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 *
178 DirtyCardToOopClosure* dcto_cl,
179 MemRegion chunk_mr,
180 MemRegion used,
181 jbyte** lowest_non_clean,
182 uintptr_t lowest_non_clean_base_chunk_index,
183 size_t lowest_non_clean_chunk_size)
184 {
185 // We must worry about non-array objects that cross chunk boundaries,
186 // because such objects are both precisely and imprecisely marked:
187 // .. if the head of such an object is dirty, the entire object
188 // needs to be scanned, under the interpretation that this
189 // was an imprecise mark
190 // .. if the head of such an object is not dirty, we can assume
191 // precise marking and it's efficient to scan just the dirty
192 // cards.
193 // In either case, each scanned reference must be scanned precisely
194 // once so as to avoid cloning of a young referent. For efficiency,
195 // our closures depend on this property and do not protect against
196 // double scans.
197
198 uintptr_t start_chunk_index = addr_to_chunk_index(chunk_mr.start());
199 uintptr_t cur_chunk_index = start_chunk_index - lowest_non_clean_base_chunk_index;
200
201 NOISY(tty->print_cr("===========================================================================");)
202 NOISY(tty->print_cr(" process_chunk_boundary: Called with [" PTR_FORMAT "," PTR_FORMAT ")",
203 chunk_mr.start(), chunk_mr.end());)
204
205 // First, set "our" lowest_non_clean entry, which would be
206 // used by the thread scanning an adjoining left chunk with
207 // a non-array object straddling the mutual boundary.
208 // Find the object that spans our boundary, if one exists.
209 // first_block is the block possibly straddling our left boundary.
210 HeapWord* first_block = sp->block_start(chunk_mr.start());
211 assert((chunk_mr.start() != used.start()) || (first_block == chunk_mr.start()),
212 "First chunk should always have a co-initial block");
213 // Does the block straddle the chunk's left boundary, and is it
214 // a non-array object?
215 if (first_block < chunk_mr.start() // first block straddles left bdry
216 && sp->block_is_obj(first_block) // first block is an object
217 && !(oop(first_block)->is_objArray() // first block is not an array (arrays are precisely dirtied)
218 || oop(first_block)->is_typeArray())) {
219 // Find our least non-clean card, so that a left neighbor
225 byte_for(first_block + sp->block_size(first_block) - 1);
226 jbyte* first_card_of_cur_chunk = byte_for(chunk_mr.start());
227 jbyte* last_card_of_cur_chunk = byte_for(chunk_mr.last());
228 jbyte* last_card_to_check =
229 (jbyte*) MIN2((intptr_t) last_card_of_cur_chunk,
230 (intptr_t) last_card_of_first_obj);
231 // Note that this does not need to go beyond our last card
232 // if our first object completely straddles this chunk.
233 for (jbyte* cur = first_card_of_cur_chunk;
234 cur <= last_card_to_check; cur++) {
235 jbyte val = *cur;
236 if (card_will_be_scanned(val)) {
237 first_dirty_card = cur; break;
238 } else {
239 assert(!card_may_have_been_dirty(val), "Error");
240 }
241 }
242 if (first_dirty_card != NULL) {
243 NOISY(tty->print_cr(" LNC: Found a dirty card at " PTR_FORMAT " in current chunk",
244 first_dirty_card);)
245 assert(start_chunk_index >= lowest_non_clean_base_chunk_index && // Check underflow.
246 cur_chunk_index < lowest_non_clean_chunk_size,
247 "Bounds error.");
248 assert(lowest_non_clean[cur_chunk_index] == NULL,
249 "Write exactly once : value should be stable hereafter for this round");
250 lowest_non_clean[cur_chunk_index] = first_dirty_card;
251 } NOISY(else {
252 tty->print_cr(" LNC: Found no dirty card in current chunk; leaving LNC entry NULL");
253 // In the future, we could have this thread look for a non-NULL value to copy from its
254 // right neighbor (up to the end of the first object).
255 if (last_card_of_cur_chunk < last_card_of_first_obj) {
256 tty->print_cr(" LNC: BEWARE!!! first obj straddles past right end of chunk:\n"
257 " might be efficient to get value from right neighbor?");
258 }
259 })
260 } else {
261 // In this case we can help our neighbor by just asking them
262 // to stop at our first card (even though it may not be dirty).
263 NOISY(tty->print_cr(" LNC: first block is not a non-array object; setting LNC to first card of current chunk");)
264 assert(lowest_non_clean[cur_chunk_index] == NULL, "Write once : value should be stable hereafter");
265 jbyte* first_card_of_cur_chunk = byte_for(chunk_mr.start());
266 lowest_non_clean[cur_chunk_index] = first_card_of_cur_chunk;
|