1.1 --- a/src/share/vm/gc_implementation/parallelScavenge/cardTableExtension.cpp Mon Oct 01 13:29:11 2012 +0200
1.2 +++ b/src/share/vm/gc_implementation/parallelScavenge/cardTableExtension.cpp Wed Oct 03 08:08:52 2012 -0700
1.3 @@ -121,103 +121,12 @@
1.4
1.5 // We get passed the space_top value to prevent us from traversing into
1.6 // the old_gen promotion labs, which cannot be safely parsed.
1.7 -void CardTableExtension::scavenge_contents(ObjectStartArray* start_array,
1.8 - MutableSpace* sp,
1.9 - HeapWord* space_top,
1.10 - PSPromotionManager* pm)
1.11 -{
1.12 - assert(start_array != NULL && sp != NULL && pm != NULL, "Sanity");
1.13 - assert(start_array->covered_region().contains(sp->used_region()),
1.14 - "ObjectStartArray does not cover space");
1.15
1.16 - if (sp->not_empty()) {
1.17 - oop* sp_top = (oop*)space_top;
1.18 - oop* prev_top = NULL;
1.19 - jbyte* current_card = byte_for(sp->bottom());
1.20 - jbyte* end_card = byte_for(sp_top - 1); // sp_top is exclusive
1.21 - // scan card marking array
1.22 - while (current_card <= end_card) {
1.23 - jbyte value = *current_card;
1.24 - // skip clean cards
1.25 - if (card_is_clean(value)) {
1.26 - current_card++;
1.27 - } else {
1.28 - // we found a non-clean card
1.29 - jbyte* first_nonclean_card = current_card++;
1.30 - oop* bottom = (oop*)addr_for(first_nonclean_card);
1.31 - // find object starting on card
1.32 - oop* bottom_obj = (oop*)start_array->object_start((HeapWord*)bottom);
1.33 - // bottom_obj = (oop*)start_array->object_start((HeapWord*)bottom);
1.34 - assert(bottom_obj <= bottom, "just checking");
1.35 - // make sure we don't scan oops we already looked at
1.36 - if (bottom < prev_top) bottom = prev_top;
1.37 - // figure out when to stop scanning
1.38 - jbyte* first_clean_card;
1.39 - oop* top;
1.40 - bool restart_scanning;
1.41 - do {
1.42 - restart_scanning = false;
1.43 - // find a clean card
1.44 - while (current_card <= end_card) {
1.45 - value = *current_card;
1.46 - if (card_is_clean(value)) break;
1.47 - current_card++;
1.48 - }
1.49 - // check if we reached the end, if so we are done
1.50 - if (current_card >= end_card) {
1.51 - first_clean_card = end_card + 1;
1.52 - current_card++;
1.53 - top = sp_top;
1.54 - } else {
1.55 - // we have a clean card, find object starting on that card
1.56 - first_clean_card = current_card++;
1.57 - top = (oop*)addr_for(first_clean_card);
1.58 - oop* top_obj = (oop*)start_array->object_start((HeapWord*)top);
1.59 - // top_obj = (oop*)start_array->object_start((HeapWord*)top);
1.60 - assert(top_obj <= top, "just checking");
1.61 - if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) {
1.62 - // an arrayOop is starting on the clean card - since we do exact store
1.63 - // checks for objArrays we are done
1.64 - } else {
1.65 - // otherwise, it is possible that the object starting on the clean card
1.66 - // spans the entire card, and that the store happened on a later card.
1.67 - // figure out where the object ends
1.68 - top = top_obj + oop(top_obj)->size();
1.69 - jbyte* top_card = CardTableModRefBS::byte_for(top - 1); // top is exclusive
1.70 - if (top_card > first_clean_card) {
1.71 - // object ends a different card
1.72 - current_card = top_card + 1;
1.73 - if (card_is_clean(*top_card)) {
1.74 - // the ending card is clean, we are done
1.75 - first_clean_card = top_card;
1.76 - } else {
1.77 - // the ending card is not clean, continue scanning at start of do-while
1.78 - restart_scanning = true;
1.79 - }
1.80 - } else {
1.81 - // object ends on the clean card, we are done.
1.82 - assert(first_clean_card == top_card, "just checking");
1.83 - }
1.84 - }
1.85 - }
1.86 - } while (restart_scanning);
1.87 - // we know which cards to scan, now clear them
1.88 - while (first_nonclean_card < first_clean_card) {
1.89 - *first_nonclean_card++ = clean_card;
1.90 - }
1.91 - // scan oops in objects
1.92 - do {
1.93 - oop(bottom_obj)->push_contents(pm);
1.94 - bottom_obj += oop(bottom_obj)->size();
1.95 - assert(bottom_obj <= sp_top, "just checking");
1.96 - } while (bottom_obj < top);
1.97 - pm->drain_stacks_cond_depth();
1.98 - // remember top oop* scanned
1.99 - prev_top = top;
1.100 - }
1.101 - }
1.102 - }
1.103 -}
1.104 +// Do not call this method if the space is empty.
1.105 +// It is a waste to start tasks and get here only to
1.106 +// do no work. If this method needs to be called
1.107 +// when the space is empty, fix the calculation of
1.108 +// end_card to allow sp_top == sp->bottom().
1.109
1.110 void CardTableExtension::scavenge_contents_parallel(ObjectStartArray* start_array,
1.111 MutableSpace* sp,
1.112 @@ -228,10 +137,11 @@
1.113 int ssize = 128; // Naked constant! Work unit = 64k.
1.114 int dirty_card_count = 0;
1.115
1.116 + // It is a waste to get here if empty.
1.117 + assert(sp->bottom() < sp->top(), "Should not be called if empty");
1.118 oop* sp_top = (oop*)space_top;
1.119 - oop* sp_last = sp->bottom() == space_top ? sp_top : sp_top - 1;
1.120 jbyte* start_card = byte_for(sp->bottom());
1.121 - jbyte* end_card = byte_for(sp_last) + 1;
1.122 + jbyte* end_card = byte_for(sp_top - 1) + 1;
1.123 oop* last_scanned = NULL; // Prevent scanning objects more than once
1.124 // The width of the stripe ssize*stripe_total must be
1.125 // consistent with the number of stripes so that the complete slice
1.126 @@ -255,6 +165,16 @@
1.127 HeapWord* slice_start = addr_for(worker_start_card);
1.128 HeapWord* slice_end = MIN2((HeapWord*) sp_top, addr_for(worker_end_card));
1.129
1.130 +#ifdef ASSERT
1.131 + if (GCWorkerDelayMillis > 0) {
1.132 + // Delay 1 worker so that it proceeds after all the work
1.133 + // has been completed.
1.134 + if (stripe_number < 2) {
1.135 + os::sleep(Thread::current(), GCWorkerDelayMillis, false);
1.136 + }
1.137 + }
1.138 +#endif
1.139 +
1.140 // If there are not objects starting within the chunk, skip it.
1.141 if (!start_array->object_starts_in_range(slice_start, slice_end)) {
1.142 continue;
