--- a/hotspot/src/share/vm/gc_implementation/parallelScavenge/cardTableExtension.cpp Mon Oct 01 13:29:11 2012 +0200
+++ b/hotspot/src/share/vm/gc_implementation/parallelScavenge/cardTableExtension.cpp Wed Oct 03 08:08:52 2012 -0700
@@ -121,103 +121,12 @@
// 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");
- 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
- 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();
- // remember top oop* scanned
- prev_top = top;
- }
- }
- }
-}
+// Do not call this method if the space is empty.
+// It is a waste to start tasks and get here only to
+// do no work. If this method needs to be called
+// when the space is empty, fix the calculation of
+// end_card to allow sp_top == sp->bottom().
void CardTableExtension::scavenge_contents_parallel(ObjectStartArray* start_array,
MutableSpace* sp,
@@ -228,10 +137,11 @@
int ssize = 128; // Naked constant! Work unit = 64k.
int dirty_card_count = 0;
+ // It is a waste to get here if empty.
+ assert(sp->bottom() < sp->top(), "Should not be called if empty");
oop* sp_top = (oop*)space_top;
- oop* sp_last = sp->bottom() == space_top ? sp_top : sp_top - 1;
jbyte* start_card = byte_for(sp->bottom());
- jbyte* end_card = byte_for(sp_last) + 1;
+ jbyte* end_card = byte_for(sp_top - 1) + 1;
oop* last_scanned = NULL; // Prevent scanning objects more than once
// The width of the stripe ssize*stripe_total must be
// consistent with the number of stripes so that the complete slice
@@ -255,6 +165,16 @@
HeapWord* slice_start = addr_for(worker_start_card);
HeapWord* slice_end = MIN2((HeapWord*) sp_top, addr_for(worker_end_card));
+#ifdef ASSERT
+ if (GCWorkerDelayMillis > 0) {
+ // Delay 1 worker so that it proceeds after all the work
+ // has been completed.
+ if (stripe_number < 2) {
+ os::sleep(Thread::current(), GCWorkerDelayMillis, false);
+ }
+ }
+#endif
+
// If there are not objects starting within the chunk, skip it.
if (!start_array->object_starts_in_range(slice_start, slice_end)) {
continue;
--- a/hotspot/src/share/vm/gc_implementation/parallelScavenge/cardTableExtension.hpp Mon Oct 01 13:29:11 2012 +0200
+++ b/hotspot/src/share/vm/gc_implementation/parallelScavenge/cardTableExtension.hpp Wed Oct 03 08:08:52 2012 -0700
@@ -60,11 +60,6 @@
// BarrierSet::Name kind() { return BarrierSet::CardTableExtension; }
// Scavenge support
- void scavenge_contents(ObjectStartArray* start_array,
- MutableSpace* sp,
- HeapWord* space_top,
- PSPromotionManager* pm);
-
void scavenge_contents_parallel(ObjectStartArray* start_array,
MutableSpace* sp,
HeapWord* space_top,
--- a/hotspot/src/share/vm/gc_implementation/parallelScavenge/psPromotionManager.inline.hpp Mon Oct 01 13:29:11 2012 +0200
+++ b/hotspot/src/share/vm/gc_implementation/parallelScavenge/psPromotionManager.inline.hpp Wed Oct 03 08:08:52 2012 -0700
@@ -136,6 +136,13 @@
HeapWord* lab_base = old_gen()->cas_allocate(OldPLABSize);
if(lab_base != NULL) {
+#ifdef ASSERT
+ // Delay the initialization of the promotion lab (plab).
+ // This exposes uninitialized plabs to card table processing.
+ if (GCWorkerDelayMillis > 0) {
+ os::sleep(Thread::current(), GCWorkerDelayMillis, false);
+ }
+#endif
_old_lab.initialize(MemRegion(lab_base, OldPLABSize));
// Try the old lab allocation again.
new_obj = (oop) _old_lab.allocate(new_obj_size);
--- a/hotspot/src/share/vm/gc_implementation/parallelScavenge/psScavenge.cpp Mon Oct 01 13:29:11 2012 +0200
+++ b/hotspot/src/share/vm/gc_implementation/parallelScavenge/psScavenge.cpp Wed Oct 03 08:08:52 2012 -0700
@@ -395,9 +395,13 @@
GCTaskQueue* q = GCTaskQueue::create();
- uint stripe_total = active_workers;
- for(uint i=0; i < stripe_total; i++) {
- q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i, stripe_total));
+ if (!old_gen->object_space()->is_empty()) {
+ // There are only old-to-young pointers if there are objects
+ // in the old gen.
+ uint stripe_total = active_workers;
+ for(uint i=0; i < stripe_total; i++) {
+ q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i, stripe_total));
+ }
}
q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe));
--- a/hotspot/src/share/vm/gc_implementation/parallelScavenge/psTasks.cpp Mon Oct 01 13:29:11 2012 +0200
+++ b/hotspot/src/share/vm/gc_implementation/parallelScavenge/psTasks.cpp Wed Oct 03 08:08:52 2012 -0700
@@ -165,35 +165,13 @@
}
//
-// SerialOldToYoungRootsTask
-//
-
-void SerialOldToYoungRootsTask::do_it(GCTaskManager* manager, uint which) {
- assert(_gen != NULL, "Sanity");
- assert(_gen->object_space()->contains(_gen_top) || _gen_top == _gen->object_space()->top(), "Sanity");
-
- {
- PSPromotionManager* pm = PSPromotionManager::gc_thread_promotion_manager(which);
-
- assert(Universe::heap()->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
- CardTableExtension* card_table = (CardTableExtension *)Universe::heap()->barrier_set();
- // FIX ME! Assert that card_table is the type we believe it to be.
-
- card_table->scavenge_contents(_gen->start_array(),
- _gen->object_space(),
- _gen_top,
- pm);
-
- // Do the real work
- pm->drain_stacks(false);
- }
-}
-
-//
// OldToYoungRootsTask
//
void OldToYoungRootsTask::do_it(GCTaskManager* manager, uint which) {
+ // There are not old-to-young pointers if the old gen is empty.
+ assert(!_gen->object_space()->is_empty(),
+ "Should not be called is there is no work");
assert(_gen != NULL, "Sanity");
assert(_gen->object_space()->contains(_gen_top) || _gen_top == _gen->object_space()->top(), "Sanity");
assert(_stripe_number < ParallelGCThreads, "Sanity");
--- a/hotspot/src/share/vm/gc_implementation/parallelScavenge/psTasks.hpp Mon Oct 01 13:29:11 2012 +0200
+++ b/hotspot/src/share/vm/gc_implementation/parallelScavenge/psTasks.hpp Wed Oct 03 08:08:52 2012 -0700
@@ -113,25 +113,6 @@
};
//
-// SerialOldToYoungRootsTask
-//
-// This task is used to scan for roots in the perm gen
-
-class SerialOldToYoungRootsTask : public GCTask {
- private:
- PSOldGen* _gen;
- HeapWord* _gen_top;
-
- public:
- SerialOldToYoungRootsTask(PSOldGen *gen, HeapWord* gen_top) :
- _gen(gen), _gen_top(gen_top) { }
-
- char* name() { return (char *)"serial-old-to-young-roots-task"; }
-
- virtual void do_it(GCTaskManager* manager, uint which);
-};
-
-//
// OldToYoungRootsTask
//
// This task is used to scan old to young roots in parallel
--- a/hotspot/src/share/vm/runtime/globals.hpp Mon Oct 01 13:29:11 2012 +0200
+++ b/hotspot/src/share/vm/runtime/globals.hpp Wed Oct 03 08:08:52 2012 -0700
@@ -3065,6 +3065,9 @@
develop(uintx, GCExpandToAllocateDelayMillis, 0, \
"Delay in ms between expansion and allocation") \
\
+ develop(uintx, GCWorkerDelayMillis, 0, \
+ "Delay in ms in scheduling GC workers") \
+ \
product(intx, DeferThrSuspendLoopCount, 4000, \
"(Unstable) Number of times to iterate in safepoint loop " \
" before blocking VM threads ") \