--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc_implementation/parallelScavenge/cardTableExtension.cpp Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,779 @@
+/*
+ * Copyright 2001-2006 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/_cardTableExtension.cpp.incl"
+
+// Checks an individual oop for missing precise marks. Mark
+// may be either dirty or newgen.
+class CheckForUnmarkedOops : public OopClosure {
+ PSYoungGen* _young_gen;
+ CardTableExtension* _card_table;
+ HeapWord* _unmarked_addr;
+ jbyte* _unmarked_card;
+
+ public:
+ CheckForUnmarkedOops( PSYoungGen* young_gen, CardTableExtension* card_table ) :
+ _young_gen(young_gen), _card_table(card_table), _unmarked_addr(NULL) { }
+
+ virtual void do_oop(oop* p) {
+ if (_young_gen->is_in_reserved(*p) &&
+ !_card_table->addr_is_marked_imprecise(p)) {
+ // Don't overwrite the first missing card mark
+ if (_unmarked_addr == NULL) {
+ _unmarked_addr = (HeapWord*)p;
+ _unmarked_card = _card_table->byte_for(p);
+ }
+ }
+ }
+
+ bool has_unmarked_oop() {
+ return _unmarked_addr != NULL;
+ }
+};
+
+// Checks all objects for the existance of some type of mark,
+// precise or imprecise, dirty or newgen.
+class CheckForUnmarkedObjects : public ObjectClosure {
+ PSYoungGen* _young_gen;
+ CardTableExtension* _card_table;
+
+ public:
+ CheckForUnmarkedObjects() {
+ ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
+ assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
+
+ _young_gen = heap->young_gen();
+ _card_table = (CardTableExtension*)heap->barrier_set();
+ // No point in asserting barrier set type here. Need to make CardTableExtension
+ // a unique barrier set type.
+ }
+
+ // Card marks are not precise. The current system can leave us with
+ // a mismash of precise marks and begining of object marks. This means
+ // we test for missing precise marks first. If any are found, we don't
+ // fail unless the object head is also unmarked.
+ virtual void do_object(oop obj) {
+ CheckForUnmarkedOops object_check( _young_gen, _card_table );
+ obj->oop_iterate(&object_check);
+ if (object_check.has_unmarked_oop()) {
+ assert(_card_table->addr_is_marked_imprecise(obj), "Found unmarked young_gen object");
+ }
+ }
+};
+
+// Checks for precise marking of oops as newgen.
+class CheckForPreciseMarks : public OopClosure {
+ PSYoungGen* _young_gen;
+ CardTableExtension* _card_table;
+
+ public:
+ CheckForPreciseMarks( PSYoungGen* young_gen, CardTableExtension* card_table ) :
+ _young_gen(young_gen), _card_table(card_table) { }
+
+ virtual void do_oop(oop* p) {
+ if (_young_gen->is_in_reserved(*p)) {
+ assert(_card_table->addr_is_marked_precise(p), "Found unmarked precise oop");
+ _card_table->set_card_newgen(p);
+ }
+ }
+};
+
+// We get passed the space_top value to prevent us from traversing into
+// the old_gen promotion labs, which cannot be safely parsed.
+void CardTableExtension::scavenge_contents(ObjectStartArray* start_array,
+ MutableSpace* sp,
+ HeapWord* space_top,
+ PSPromotionManager* pm)
+{
+ assert(start_array != NULL && sp != NULL && pm != NULL, "Sanity");
+ assert(start_array->covered_region().contains(sp->used_region()),
+ "ObjectStartArray does not cover space");
+ bool depth_first = pm->depth_first();
+
+ if (sp->not_empty()) {
+ oop* sp_top = (oop*)space_top;
+ oop* prev_top = NULL;
+ jbyte* current_card = byte_for(sp->bottom());
+ jbyte* end_card = byte_for(sp_top - 1); // sp_top is exclusive
+ // scan card marking array
+ while (current_card <= end_card) {
+ jbyte value = *current_card;
+ // skip clean cards
+ if (card_is_clean(value)) {
+ current_card++;
+ } else {
+ // we found a non-clean card
+ jbyte* first_nonclean_card = current_card++;
+ oop* bottom = (oop*)addr_for(first_nonclean_card);
+ // find object starting on card
+ oop* bottom_obj = (oop*)start_array->object_start((HeapWord*)bottom);
+ // bottom_obj = (oop*)start_array->object_start((HeapWord*)bottom);
+ assert(bottom_obj <= bottom, "just checking");
+ // make sure we don't scan oops we already looked at
+ if (bottom < prev_top) bottom = prev_top;
+ // figure out when to stop scanning
+ jbyte* first_clean_card;
+ oop* top;
+ bool restart_scanning;
+ do {
+ restart_scanning = false;
+ // find a clean card
+ while (current_card <= end_card) {
+ value = *current_card;
+ if (card_is_clean(value)) break;
+ current_card++;
+ }
+ // check if we reached the end, if so we are done
+ if (current_card >= end_card) {
+ first_clean_card = end_card + 1;
+ current_card++;
+ top = sp_top;
+ } else {
+ // we have a clean card, find object starting on that card
+ first_clean_card = current_card++;
+ top = (oop*)addr_for(first_clean_card);
+ oop* top_obj = (oop*)start_array->object_start((HeapWord*)top);
+ // top_obj = (oop*)start_array->object_start((HeapWord*)top);
+ assert(top_obj <= top, "just checking");
+ if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) {
+ // an arrayOop is starting on the clean card - since we do exact store
+ // checks for objArrays we are done
+ } else {
+ // otherwise, it is possible that the object starting on the clean card
+ // spans the entire card, and that the store happened on a later card.
+ // figure out where the object ends
+ top = top_obj + oop(top_obj)->size();
+ jbyte* top_card = CardTableModRefBS::byte_for(top - 1); // top is exclusive
+ if (top_card > first_clean_card) {
+ // object ends a different card
+ current_card = top_card + 1;
+ if (card_is_clean(*top_card)) {
+ // the ending card is clean, we are done
+ first_clean_card = top_card;
+ } else {
+ // the ending card is not clean, continue scanning at start of do-while
+ restart_scanning = true;
+ }
+ } else {
+ // object ends on the clean card, we are done.
+ assert(first_clean_card == top_card, "just checking");
+ }
+ }
+ }
+ } while (restart_scanning);
+ // we know which cards to scan, now clear them
+ while (first_nonclean_card < first_clean_card) {
+ *first_nonclean_card++ = clean_card;
+ }
+ // scan oops in objects
+ // hoisted the if (depth_first) check out of the loop
+ if (depth_first){
+ do {
+ oop(bottom_obj)->push_contents(pm);
+ bottom_obj += oop(bottom_obj)->size();
+ assert(bottom_obj <= sp_top, "just checking");
+ } while (bottom_obj < top);
+ pm->drain_stacks_cond_depth();
+ } else {
+ do {
+ oop(bottom_obj)->copy_contents(pm);
+ bottom_obj += oop(bottom_obj)->size();
+ assert(bottom_obj <= sp_top, "just checking");
+ } while (bottom_obj < top);
+ }
+ // remember top oop* scanned
+ prev_top = top;
+ }
+ }
+ }
+}
+
+void CardTableExtension::scavenge_contents_parallel(ObjectStartArray* start_array,
+ MutableSpace* sp,
+ HeapWord* space_top,
+ PSPromotionManager* pm,
+ uint stripe_number) {
+ int ssize = 128; // Naked constant! Work unit = 64k.
+ int dirty_card_count = 0;
+ bool depth_first = pm->depth_first();
+
+ oop* sp_top = (oop*)space_top;
+ jbyte* start_card = byte_for(sp->bottom());
+ jbyte* end_card = byte_for(sp_top - 1) + 1;
+ oop* last_scanned = NULL; // Prevent scanning objects more than once
+ for (jbyte* slice = start_card; slice < end_card; slice += ssize*ParallelGCThreads) {
+ jbyte* worker_start_card = slice + stripe_number * ssize;
+ if (worker_start_card >= end_card)
+ return; // We're done.
+
+ jbyte* worker_end_card = worker_start_card + ssize;
+ if (worker_end_card > end_card)
+ worker_end_card = end_card;
+
+ // We do not want to scan objects more than once. In order to accomplish
+ // this, we assert that any object with an object head inside our 'slice'
+ // belongs to us. We may need to extend the range of scanned cards if the
+ // last object continues into the next 'slice'.
+ //
+ // Note! ending cards are exclusive!
+ HeapWord* slice_start = addr_for(worker_start_card);
+ HeapWord* slice_end = MIN2((HeapWord*) sp_top, addr_for(worker_end_card));
+
+ // If there are not objects starting within the chunk, skip it.
+ if (!start_array->object_starts_in_range(slice_start, slice_end)) {
+ continue;
+ }
+ // Update our begining addr
+ HeapWord* first_object = start_array->object_start(slice_start);
+ debug_only(oop* first_object_within_slice = (oop*) first_object;)
+ if (first_object < slice_start) {
+ last_scanned = (oop*)(first_object + oop(first_object)->size());
+ debug_only(first_object_within_slice = last_scanned;)
+ worker_start_card = byte_for(last_scanned);
+ }
+
+ // Update the ending addr
+ if (slice_end < (HeapWord*)sp_top) {
+ // The subtraction is important! An object may start precisely at slice_end.
+ HeapWord* last_object = start_array->object_start(slice_end - 1);
+ slice_end = last_object + oop(last_object)->size();
+ // worker_end_card is exclusive, so bump it one past the end of last_object's
+ // covered span.
+ worker_end_card = byte_for(slice_end) + 1;
+
+ if (worker_end_card > end_card)
+ worker_end_card = end_card;
+ }
+
+ assert(slice_end <= (HeapWord*)sp_top, "Last object in slice crosses space boundary");
+ assert(is_valid_card_address(worker_start_card), "Invalid worker start card");
+ assert(is_valid_card_address(worker_end_card), "Invalid worker end card");
+ // Note that worker_start_card >= worker_end_card is legal, and happens when
+ // an object spans an entire slice.
+ assert(worker_start_card <= end_card, "worker start card beyond end card");
+ assert(worker_end_card <= end_card, "worker end card beyond end card");
+
+ jbyte* current_card = worker_start_card;
+ while (current_card < worker_end_card) {
+ // Find an unclean card.
+ while (current_card < worker_end_card && card_is_clean(*current_card)) {
+ current_card++;
+ }
+ jbyte* first_unclean_card = current_card;
+
+ // Find the end of a run of contiguous unclean cards
+ while (current_card < worker_end_card && !card_is_clean(*current_card)) {
+ while (current_card < worker_end_card && !card_is_clean(*current_card)) {
+ current_card++;
+ }
+
+ if (current_card < worker_end_card) {
+ // Some objects may be large enough to span several cards. If such
+ // an object has more than one dirty card, separated by a clean card,
+ // we will attempt to scan it twice. The test against "last_scanned"
+ // prevents the redundant object scan, but it does not prevent newly
+ // marked cards from being cleaned.
+ HeapWord* last_object_in_dirty_region = start_array->object_start(addr_for(current_card)-1);
+ size_t size_of_last_object = oop(last_object_in_dirty_region)->size();
+ HeapWord* end_of_last_object = last_object_in_dirty_region + size_of_last_object;
+ jbyte* ending_card_of_last_object = byte_for(end_of_last_object);
+ assert(ending_card_of_last_object <= worker_end_card, "ending_card_of_last_object is greater than worker_end_card");
+ if (ending_card_of_last_object > current_card) {
+ // This means the object spans the next complete card.
+ // We need to bump the current_card to ending_card_of_last_object
+ current_card = ending_card_of_last_object;
+ }
+ }
+ }
+ jbyte* following_clean_card = current_card;
+
+ if (first_unclean_card < worker_end_card) {
+ oop* p = (oop*) start_array->object_start(addr_for(first_unclean_card));
+ assert((HeapWord*)p <= addr_for(first_unclean_card), "checking");
+ // "p" should always be >= "last_scanned" because newly GC dirtied
+ // cards are no longer scanned again (see comment at end
+ // of loop on the increment of "current_card"). Test that
+ // hypothesis before removing this code.
+ // If this code is removed, deal with the first time through
+ // the loop when the last_scanned is the object starting in
+ // the previous slice.
+ assert((p >= last_scanned) ||
+ (last_scanned == first_object_within_slice),
+ "Should no longer be possible");
+ if (p < last_scanned) {
+ // Avoid scanning more than once; this can happen because
+ // newgen cards set by GC may a different set than the
+ // originally dirty set
+ p = last_scanned;
+ }
+ oop* to = (oop*)addr_for(following_clean_card);
+
+ // Test slice_end first!
+ if ((HeapWord*)to > slice_end) {
+ to = (oop*)slice_end;
+ } else if (to > sp_top) {
+ to = sp_top;
+ }
+
+ // we know which cards to scan, now clear them
+ if (first_unclean_card <= worker_start_card+1)
+ first_unclean_card = worker_start_card+1;
+ if (following_clean_card >= worker_end_card-1)
+ following_clean_card = worker_end_card-1;
+
+ while (first_unclean_card < following_clean_card) {
+ *first_unclean_card++ = clean_card;
+ }
+
+ const int interval = PrefetchScanIntervalInBytes;
+ // scan all objects in the range
+ if (interval != 0) {
+ // hoisted the if (depth_first) check out of the loop
+ if (depth_first) {
+ while (p < to) {
+ Prefetch::write(p, interval);
+ oop m = oop(p);
+ assert(m->is_oop_or_null(), "check for header");
+ m->push_contents(pm);
+ p += m->size();
+ }
+ pm->drain_stacks_cond_depth();
+ } else {
+ while (p < to) {
+ Prefetch::write(p, interval);
+ oop m = oop(p);
+ assert(m->is_oop_or_null(), "check for header");
+ m->copy_contents(pm);
+ p += m->size();
+ }
+ }
+ } else {
+ // hoisted the if (depth_first) check out of the loop
+ if (depth_first) {
+ while (p < to) {
+ oop m = oop(p);
+ assert(m->is_oop_or_null(), "check for header");
+ m->push_contents(pm);
+ p += m->size();
+ }
+ pm->drain_stacks_cond_depth();
+ } else {
+ while (p < to) {
+ oop m = oop(p);
+ assert(m->is_oop_or_null(), "check for header");
+ m->copy_contents(pm);
+ p += m->size();
+ }
+ }
+ }
+ last_scanned = p;
+ }
+ // "current_card" is still the "following_clean_card" or
+ // the current_card is >= the worker_end_card so the
+ // loop will not execute again.
+ assert((current_card == following_clean_card) ||
+ (current_card >= worker_end_card),
+ "current_card should only be incremented if it still equals "
+ "following_clean_card");
+ // Increment current_card so that it is not processed again.
+ // It may now be dirty because a old-to-young pointer was
+ // found on it an updated. If it is now dirty, it cannot be
+ // be safely cleaned in the next iteration.
+ current_card++;
+ }
+ }
+}
+
+// This should be called before a scavenge.
+void CardTableExtension::verify_all_young_refs_imprecise() {
+ CheckForUnmarkedObjects check;
+
+ ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
+ assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
+
+ PSOldGen* old_gen = heap->old_gen();
+ PSPermGen* perm_gen = heap->perm_gen();
+
+ old_gen->object_iterate(&check);
+ perm_gen->object_iterate(&check);
+}
+
+// This should be called immediately after a scavenge, before mutators resume.
+void CardTableExtension::verify_all_young_refs_precise() {
+ ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
+ assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
+
+ PSOldGen* old_gen = heap->old_gen();
+ PSPermGen* perm_gen = heap->perm_gen();
+
+ CheckForPreciseMarks check(heap->young_gen(), (CardTableExtension*)heap->barrier_set());
+
+ old_gen->oop_iterate(&check);
+ perm_gen->oop_iterate(&check);
+
+ verify_all_young_refs_precise_helper(old_gen->object_space()->used_region());
+ verify_all_young_refs_precise_helper(perm_gen->object_space()->used_region());
+}
+
+void CardTableExtension::verify_all_young_refs_precise_helper(MemRegion mr) {
+ CardTableExtension* card_table = (CardTableExtension*)Universe::heap()->barrier_set();
+ // FIX ME ASSERT HERE
+
+ jbyte* bot = card_table->byte_for(mr.start());
+ jbyte* top = card_table->byte_for(mr.end());
+ while(bot <= top) {
+ assert(*bot == clean_card || *bot == verify_card, "Found unwanted or unknown card mark");
+ if (*bot == verify_card)
+ *bot = youngergen_card;
+ bot++;
+ }
+}
+
+bool CardTableExtension::addr_is_marked_imprecise(void *addr) {
+ jbyte* p = byte_for(addr);
+ jbyte val = *p;
+
+ if (card_is_dirty(val))
+ return true;
+
+ if (card_is_newgen(val))
+ return true;
+
+ if (card_is_clean(val))
+ return false;
+
+ assert(false, "Found unhandled card mark type");
+
+ return false;
+}
+
+// Also includes verify_card
+bool CardTableExtension::addr_is_marked_precise(void *addr) {
+ jbyte* p = byte_for(addr);
+ jbyte val = *p;
+
+ if (card_is_newgen(val))
+ return true;
+
+ if (card_is_verify(val))
+ return true;
+
+ if (card_is_clean(val))
+ return false;
+
+ if (card_is_dirty(val))
+ return false;
+
+ assert(false, "Found unhandled card mark type");
+
+ return false;
+}
+
+// Assumes that only the base or the end changes. This allows indentification
+// of the region that is being resized. The
+// CardTableModRefBS::resize_covered_region() is used for the normal case
+// where the covered regions are growing or shrinking at the high end.
+// The method resize_covered_region_by_end() is analogous to
+// CardTableModRefBS::resize_covered_region() but
+// for regions that grow or shrink at the low end.
+void CardTableExtension::resize_covered_region(MemRegion new_region) {
+
+ for (int i = 0; i < _cur_covered_regions; i++) {
+ if (_covered[i].start() == new_region.start()) {
+ // Found a covered region with the same start as the
+ // new region. The region is growing or shrinking
+ // from the start of the region.
+ resize_covered_region_by_start(new_region);
+ return;
+ }
+ if (_covered[i].start() > new_region.start()) {
+ break;
+ }
+ }
+
+ int changed_region = -1;
+ for (int j = 0; j < _cur_covered_regions; j++) {
+ if (_covered[j].end() == new_region.end()) {
+ changed_region = j;
+ // This is a case where the covered region is growing or shrinking
+ // at the start of the region.
+ assert(changed_region != -1, "Don't expect to add a covered region");
+ assert(_covered[changed_region].byte_size() != new_region.byte_size(),
+ "The sizes should be different here");
+ resize_covered_region_by_end(changed_region, new_region);
+ return;
+ }
+ }
+ // This should only be a new covered region (where no existing
+ // covered region matches at the start or the end).
+ assert(_cur_covered_regions < _max_covered_regions,
+ "An existing region should have been found");
+ resize_covered_region_by_start(new_region);
+}
+
+void CardTableExtension::resize_covered_region_by_start(MemRegion new_region) {
+ CardTableModRefBS::resize_covered_region(new_region);
+ debug_only(verify_guard();)
+}
+
+void CardTableExtension::resize_covered_region_by_end(int changed_region,
+ MemRegion new_region) {
+ assert(SafepointSynchronize::is_at_safepoint(),
+ "Only expect an expansion at the low end at a GC");
+ debug_only(verify_guard();)
+#ifdef ASSERT
+ for (int k = 0; k < _cur_covered_regions; k++) {
+ if (_covered[k].end() == new_region.end()) {
+ assert(changed_region == k, "Changed region is incorrect");
+ break;
+ }
+ }
+#endif
+
+ // Commit new or uncommit old pages, if necessary.
+ resize_commit_uncommit(changed_region, new_region);
+
+ // Update card table entries
+ resize_update_card_table_entries(changed_region, new_region);
+
+ // Set the new start of the committed region
+ resize_update_committed_table(changed_region, new_region);
+
+ // Update the covered region
+ resize_update_covered_table(changed_region, new_region);
+
+ if (TraceCardTableModRefBS) {
+ int ind = changed_region;
+ gclog_or_tty->print_cr("CardTableModRefBS::resize_covered_region: ");
+ gclog_or_tty->print_cr(" "
+ " _covered[%d].start(): " INTPTR_FORMAT
+ " _covered[%d].last(): " INTPTR_FORMAT,
+ ind, _covered[ind].start(),
+ ind, _covered[ind].last());
+ gclog_or_tty->print_cr(" "
+ " _committed[%d].start(): " INTPTR_FORMAT
+ " _committed[%d].last(): " INTPTR_FORMAT,
+ ind, _committed[ind].start(),
+ ind, _committed[ind].last());
+ gclog_or_tty->print_cr(" "
+ " byte_for(start): " INTPTR_FORMAT
+ " byte_for(last): " INTPTR_FORMAT,
+ byte_for(_covered[ind].start()),
+ byte_for(_covered[ind].last()));
+ gclog_or_tty->print_cr(" "
+ " addr_for(start): " INTPTR_FORMAT
+ " addr_for(last): " INTPTR_FORMAT,
+ addr_for((jbyte*) _committed[ind].start()),
+ addr_for((jbyte*) _committed[ind].last()));
+ }
+ debug_only(verify_guard();)
+}
+
+void CardTableExtension::resize_commit_uncommit(int changed_region,
+ MemRegion new_region) {
+ // Commit new or uncommit old pages, if necessary.
+ MemRegion cur_committed = _committed[changed_region];
+ assert(_covered[changed_region].end() == new_region.end(),
+ "The ends of the regions are expected to match");
+ // Extend the start of this _committed region to
+ // to cover the start of any previous _committed region.
+ // This forms overlapping regions, but never interior regions.
+ HeapWord* min_prev_start = lowest_prev_committed_start(changed_region);
+ if (min_prev_start < cur_committed.start()) {
+ // Only really need to set start of "cur_committed" to
+ // the new start (min_prev_start) but assertion checking code
+ // below use cur_committed.end() so make it correct.
+ MemRegion new_committed =
+ MemRegion(min_prev_start, cur_committed.end());
+ cur_committed = new_committed;
+ }
+#ifdef ASSERT
+ ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
+ assert(cur_committed.start() ==
+ (HeapWord*) align_size_up((uintptr_t) cur_committed.start(),
+ os::vm_page_size()),
+ "Starts should have proper alignment");
+#endif
+
+ jbyte* new_start = byte_for(new_region.start());
+ // Round down because this is for the start address
+ HeapWord* new_start_aligned =
+ (HeapWord*)align_size_down((uintptr_t)new_start, os::vm_page_size());
+ // The guard page is always committed and should not be committed over.
+ // This method is used in cases where the generation is growing toward
+ // lower addresses but the guard region is still at the end of the
+ // card table. That still makes sense when looking for writes
+ // off the end of the card table.
+ if (new_start_aligned < cur_committed.start()) {
+ // Expand the committed region
+ //
+ // Case A
+ // |+ guard +|
+ // |+ cur committed +++++++++|
+ // |+ new committed +++++++++++++++++|
+ //
+ // Case B
+ // |+ guard +|
+ // |+ cur committed +|
+ // |+ new committed +++++++|
+ //
+ // These are not expected because the calculation of the
+ // cur committed region and the new committed region
+ // share the same end for the covered region.
+ // Case C
+ // |+ guard +|
+ // |+ cur committed +|
+ // |+ new committed +++++++++++++++++|
+ // Case D
+ // |+ guard +|
+ // |+ cur committed +++++++++++|
+ // |+ new committed +++++++|
+
+ HeapWord* new_end_for_commit =
+ MIN2(cur_committed.end(), _guard_region.start());
+ MemRegion new_committed =
+ MemRegion(new_start_aligned, new_end_for_commit);
+ if(!new_committed.is_empty()) {
+ if (!os::commit_memory((char*)new_committed.start(),
+ new_committed.byte_size())) {
+ vm_exit_out_of_memory(new_committed.byte_size(),
+ "card table expansion");
+ }
+ }
+ } else if (new_start_aligned > cur_committed.start()) {
+ // Shrink the committed region
+ MemRegion uncommit_region = committed_unique_to_self(changed_region,
+ MemRegion(cur_committed.start(), new_start_aligned));
+ if (!uncommit_region.is_empty()) {
+ if (!os::uncommit_memory((char*)uncommit_region.start(),
+ uncommit_region.byte_size())) {
+ vm_exit_out_of_memory(uncommit_region.byte_size(),
+ "card table contraction");
+ }
+ }
+ }
+ assert(_committed[changed_region].end() == cur_committed.end(),
+ "end should not change");
+}
+
+void CardTableExtension::resize_update_committed_table(int changed_region,
+ MemRegion new_region) {
+
+ jbyte* new_start = byte_for(new_region.start());
+ // Set the new start of the committed region
+ HeapWord* new_start_aligned =
+ (HeapWord*)align_size_down((uintptr_t)new_start,
+ os::vm_page_size());
+ MemRegion new_committed = MemRegion(new_start_aligned,
+ _committed[changed_region].end());
+ _committed[changed_region] = new_committed;
+ _committed[changed_region].set_start(new_start_aligned);
+}
+
+void CardTableExtension::resize_update_card_table_entries(int changed_region,
+ MemRegion new_region) {
+ debug_only(verify_guard();)
+ MemRegion original_covered = _covered[changed_region];
+ // Initialize the card entries. Only consider the
+ // region covered by the card table (_whole_heap)
+ jbyte* entry;
+ if (new_region.start() < _whole_heap.start()) {
+ entry = byte_for(_whole_heap.start());
+ } else {
+ entry = byte_for(new_region.start());
+ }
+ jbyte* end = byte_for(original_covered.start());
+ // If _whole_heap starts at the original covered regions start,
+ // this loop will not execute.
+ while (entry < end) { *entry++ = clean_card; }
+}
+
+void CardTableExtension::resize_update_covered_table(int changed_region,
+ MemRegion new_region) {
+ // Update the covered region
+ _covered[changed_region].set_start(new_region.start());
+ _covered[changed_region].set_word_size(new_region.word_size());
+
+ // reorder regions. There should only be at most 1 out
+ // of order.
+ for (int i = _cur_covered_regions-1 ; i > 0; i--) {
+ if (_covered[i].start() < _covered[i-1].start()) {
+ MemRegion covered_mr = _covered[i-1];
+ _covered[i-1] = _covered[i];
+ _covered[i] = covered_mr;
+ MemRegion committed_mr = _committed[i-1];
+ _committed[i-1] = _committed[i];
+ _committed[i] = committed_mr;
+ break;
+ }
+ }
+#ifdef ASSERT
+ for (int m = 0; m < _cur_covered_regions-1; m++) {
+ assert(_covered[m].start() <= _covered[m+1].start(),
+ "Covered regions out of order");
+ assert(_committed[m].start() <= _committed[m+1].start(),
+ "Committed regions out of order");
+ }
+#endif
+}
+
+// Returns the start of any committed region that is lower than
+// the target committed region (index ind) and that intersects the
+// target region. If none, return start of target region.
+//
+// -------------
+// | |
+// -------------
+// ------------
+// | target |
+// ------------
+// -------------
+// | |
+// -------------
+// ^ returns this
+//
+// -------------
+// | |
+// -------------
+// ------------
+// | target |
+// ------------
+// -------------
+// | |
+// -------------
+// ^ returns this
+
+HeapWord* CardTableExtension::lowest_prev_committed_start(int ind) const {
+ assert(_cur_covered_regions >= 0, "Expecting at least on region");
+ HeapWord* min_start = _committed[ind].start();
+ for (int j = 0; j < ind; j++) {
+ HeapWord* this_start = _committed[j].start();
+ if ((this_start < min_start) &&
+ !(_committed[j].intersection(_committed[ind])).is_empty()) {
+ min_start = this_start;
+ }
+ }
+ return min_start;
+}