src/share/vm/gc_implementation/g1/concurrentMark.cpp
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rev 2724 : 6484965: G1: piggy-back liveness accounting phase on marking
Summary: Remove the separate counting phase of concurrent marking by tracking the amount of marked bytes and the cards spanned by marked objects in marking task/worker thread local data structures, which are updated as individual objects are marked.
Reviewed-by:
@@ -471,10 +471,11 @@
_cleanup_list("Cleanup List"),
_region_bm(max_regions, false /* in_resource_area*/),
_card_bm((rs.size() + CardTableModRefBS::card_size - 1) >>
CardTableModRefBS::card_shift,
false /* in_resource_area*/),
+
_prevMarkBitMap(&_markBitMap1),
_nextMarkBitMap(&_markBitMap2),
_at_least_one_mark_complete(false),
_markStack(this),
@@ -500,11 +501,15 @@
_remark_times(), _remark_mark_times(), _remark_weak_ref_times(),
_cleanup_times(),
_total_counting_time(0.0),
_total_rs_scrub_time(0.0),
- _parallel_workers(NULL) {
+ _parallel_workers(NULL),
+
+ _count_card_bitmaps(NULL),
+ _count_marked_bytes(NULL)
+{
CMVerboseLevel verbose_level = (CMVerboseLevel) G1MarkingVerboseLevel;
if (verbose_level < no_verbose) {
verbose_level = no_verbose;
}
if (verbose_level > high_verbose) {
@@ -534,19 +539,27 @@
satb_qs.set_buffer_size(G1SATBBufferSize);
_tasks = NEW_C_HEAP_ARRAY(CMTask*, _max_task_num);
_accum_task_vtime = NEW_C_HEAP_ARRAY(double, _max_task_num);
+ _count_card_bitmaps = NEW_C_HEAP_ARRAY(BitMap, _max_task_num);
+ _count_marked_bytes = NEW_C_HEAP_ARRAY(size_t*, _max_task_num);
+
+ BitMap::idx_t card_bm_size = _card_bm.size();
+
// so that the assertion in MarkingTaskQueue::task_queue doesn't fail
_active_tasks = _max_task_num;
for (int i = 0; i < (int) _max_task_num; ++i) {
CMTaskQueue* task_queue = new CMTaskQueue();
task_queue->initialize();
_task_queues->register_queue(i, task_queue);
_tasks[i] = new CMTask(i, this, task_queue, _task_queues);
_accum_task_vtime[i] = 0.0;
+
+ _count_card_bitmaps[i] = BitMap(card_bm_size, false);
+ _count_marked_bytes[i] = NEW_C_HEAP_ARRAY(size_t, max_regions);
}
if (ConcGCThreads > ParallelGCThreads) {
vm_exit_during_initialization("Can't have more ConcGCThreads "
"than ParallelGCThreads.");
@@ -664,10 +677,12 @@
assert(_heap_start < _heap_end, "heap bounds should look ok");
// reset all the marking data structures and any necessary flags
clear_marking_state();
+ clear_all_count_data();
+
if (verbose_low()) {
gclog_or_tty->print_cr("[global] resetting");
}
// We do reset all of them, since different phases will use
@@ -719,13 +734,21 @@
ConcurrentMark::~ConcurrentMark() {
for (int i = 0; i < (int) _max_task_num; ++i) {
delete _task_queues->queue(i);
delete _tasks[i];
+
+ _count_card_bitmaps[i].resize(0, false);
+ FREE_C_HEAP_ARRAY(size_t, _count_marked_bytes[i]);
}
+
delete _task_queues;
- FREE_C_HEAP_ARRAY(CMTask*, _max_task_num);
+ FREE_C_HEAP_ARRAY(CMTask*, _tasks);
+ FREE_C_HEAP_ARRAY(double, _accum_task_vtime);
+
+ FREE_C_HEAP_ARRAY(BitMap*, _count_card_bitmaps);
+ FREE_C_HEAP_ARRAY(size_t*, _count_marked_bytes);
}
// This closure is used to mark refs into the g1 generation
// from external roots in the CMS bit map.
// Called at the first checkpoint.
@@ -940,22 +963,25 @@
return false;
}
}
#endif // !PRODUCT
-void ConcurrentMark::grayRoot(oop p) {
+void ConcurrentMark::grayRoot(oop p, int worker_i) {
HeapWord* addr = (HeapWord*) p;
// We can't really check against _heap_start and _heap_end, since it
// is possible during an evacuation pause with piggy-backed
// initial-mark that the committed space is expanded during the
// pause without CM observing this change. So the assertions below
// is a bit conservative; but better than nothing.
assert(_g1h->g1_committed().contains(addr),
"address should be within the heap bounds");
if (!_nextMarkBitMap->isMarked(addr)) {
- _nextMarkBitMap->parMark(addr);
+ if (_nextMarkBitMap->parMark(addr)) {
+ // Update the task specific count data for object p.
+ add_to_count_data_for(p, worker_i);
+ }
}
}
void ConcurrentMark::grayRegionIfNecessary(MemRegion mr) {
// The objects on the region have already been marked "in bulk" by
@@ -1000,19 +1026,22 @@
}
}
}
}
-void ConcurrentMark::markAndGrayObjectIfNecessary(oop p) {
+void ConcurrentMark::markAndGrayObjectIfNecessary(oop p, int worker_i) {
// The object is not marked by the caller. We need to at least mark
// it and maybe push in on the stack.
HeapWord* addr = (HeapWord*)p;
if (!_nextMarkBitMap->isMarked(addr)) {
// We definitely need to mark it, irrespective whether we bail out
// because we're done with marking.
if (_nextMarkBitMap->parMark(addr)) {
+ // Update the task specific count data for object p
+ add_to_count_data_for(p, worker_i);
+
if (!concurrent_marking_in_progress() || !_should_gray_objects) {
// If we're done with concurrent marking and we're waiting for
// remark, then we're not pushing anything on the stack.
return;
}
@@ -1171,10 +1200,14 @@
clear_has_overflown();
if (G1TraceMarkStackOverflow) {
gclog_or_tty->print_cr("\nRemark led to restart for overflow.");
}
} else {
+ // Aggregate the per-task counting data that we have accumulated
+ // while marking.
+ aggregate_all_count_data();
+
SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
// We're done with marking.
// This is the end of the marking cycle, we're expected all
// threads to have SATB queues with active set to true.
satb_mq_set.set_active_all_threads(false, /* new active value */
@@ -1210,45 +1243,46 @@
g1p->record_concurrent_mark_remark_end();
}
#define CARD_BM_TEST_MODE 0
+// Used to calculate the # live objects per region
+// for verification purposes
class CalcLiveObjectsClosure: public HeapRegionClosure {
CMBitMapRO* _bm;
ConcurrentMark* _cm;
- bool _changed;
- bool _yield;
- size_t _words_done;
+ BitMap* _region_bm;
+ BitMap* _card_bm;
+
+ size_t _tot_words_done;
size_t _tot_live;
size_t _tot_used;
- size_t _regions_done;
- double _start_vtime_sec;
- BitMap* _region_bm;
- BitMap* _card_bm;
+ size_t _region_marked_bytes;
+
intptr_t _bottom_card_num;
- bool _final;
void mark_card_num_range(intptr_t start_card_num, intptr_t last_card_num) {
- for (intptr_t i = start_card_num; i <= last_card_num; i++) {
+ BitMap::idx_t start_idx = start_card_num - _bottom_card_num;
+ BitMap::idx_t last_idx = last_card_num - _bottom_card_num;
+
+ for (BitMap::idx_t i = start_idx; i <= last_idx; i += 1) {
#if CARD_BM_TEST_MODE
- guarantee(_card_bm->at(i - _bottom_card_num), "Should already be set.");
+ guarantee(_card_bm->at(i), "Should already be set.");
#else
- _card_bm->par_at_put(i - _bottom_card_num, 1);
+ _card_bm->par_at_put(i, 1);
#endif
}
}
public:
- CalcLiveObjectsClosure(bool final,
- CMBitMapRO *bm, ConcurrentMark *cm,
+ CalcLiveObjectsClosure(CMBitMapRO *bm, ConcurrentMark *cm,
BitMap* region_bm, BitMap* card_bm) :
- _bm(bm), _cm(cm), _changed(false), _yield(true),
- _words_done(0), _tot_live(0), _tot_used(0),
- _region_bm(region_bm), _card_bm(card_bm),_final(final),
- _regions_done(0), _start_vtime_sec(0.0)
+ _bm(bm), _cm(cm), _region_bm(region_bm), _card_bm(card_bm),
+ _region_marked_bytes(0), _tot_words_done(0),
+ _tot_live(0), _tot_used(0)
{
_bottom_card_num =
intptr_t(uintptr_t(G1CollectedHeap::heap()->reserved_region().start()) >>
CardTableModRefBS::card_shift);
}
@@ -1285,13 +1319,10 @@
(BitMap::idx_t) end_index, true);
}
}
bool doHeapRegion(HeapRegion* hr) {
- if (!_final && _regions_done == 0) {
- _start_vtime_sec = os::elapsedVTime();
- }
if (hr->continuesHumongous()) {
// We will ignore these here and process them when their
// associated "starts humongous" region is processed (see
// set_bit_for_heap_region()). Note that we cannot rely on their
@@ -1301,52 +1332,44 @@
// before its associated "starts humongous".
return false;
}
HeapWord* nextTop = hr->next_top_at_mark_start();
- HeapWord* start = hr->top_at_conc_mark_count();
- assert(hr->bottom() <= start && start <= hr->end() &&
- hr->bottom() <= nextTop && nextTop <= hr->end() &&
- start <= nextTop,
+ HeapWord* start = hr->bottom();
+
+ assert(start <= hr->end() && start <= nextTop && nextTop <= hr->end(),
"Preconditions.");
- // Otherwise, record the number of word's we'll examine.
+
+ // Record the number of word's we'll examine.
size_t words_done = (nextTop - start);
+
// Find the first marked object at or after "start".
start = _bm->getNextMarkedWordAddress(start, nextTop);
+
size_t marked_bytes = 0;
+ _region_marked_bytes = 0;
// Below, the term "card num" means the result of shifting an address
// by the card shift -- address 0 corresponds to card number 0. One
// must subtract the card num of the bottom of the heap to obtain a
// card table index.
+
// The first card num of the sequence of live cards currently being
// constructed. -1 ==> no sequence.
intptr_t start_card_num = -1;
+
// The last card num of the sequence of live cards currently being
// constructed. -1 ==> no sequence.
intptr_t last_card_num = -1;
while (start < nextTop) {
- if (_yield && _cm->do_yield_check()) {
- // We yielded. It might be for a full collection, in which case
- // all bets are off; terminate the traversal.
- if (_cm->has_aborted()) {
- _changed = false;
- return true;
- } else {
- // Otherwise, it might be a collection pause, and the region
- // we're looking at might be in the collection set. We'll
- // abandon this region.
- return false;
- }
- }
oop obj = oop(start);
int obj_sz = obj->size();
+
// The card num of the start of the current object.
intptr_t obj_card_num =
intptr_t(uintptr_t(start) >> CardTableModRefBS::card_shift);
-
HeapWord* obj_last = start + obj_sz - 1;
intptr_t obj_last_card_num =
intptr_t(uintptr_t(obj_last) >> CardTableModRefBS::card_shift);
if (obj_card_num != last_card_num) {
@@ -1375,140 +1398,543 @@
}
// In any case, we set the last card num.
last_card_num = obj_last_card_num;
marked_bytes += (size_t)obj_sz * HeapWordSize;
+
// Find the next marked object after this one.
start = _bm->getNextMarkedWordAddress(start + 1, nextTop);
- _changed = true;
}
+
// Handle the last range, if any.
if (start_card_num != -1) {
mark_card_num_range(start_card_num, last_card_num);
}
- if (_final) {
+
// Mark the allocated-since-marking portion...
- HeapWord* tp = hr->top();
- if (nextTop < tp) {
- start_card_num =
- intptr_t(uintptr_t(nextTop) >> CardTableModRefBS::card_shift);
- last_card_num =
- intptr_t(uintptr_t(tp) >> CardTableModRefBS::card_shift);
+ HeapWord* top = hr->top();
+ if (nextTop < top) {
+ start_card_num = intptr_t(uintptr_t(nextTop) >> CardTableModRefBS::card_shift);
+ last_card_num = intptr_t(uintptr_t(top) >> CardTableModRefBS::card_shift);
+
mark_card_num_range(start_card_num, last_card_num);
+
// This definitely means the region has live objects.
set_bit_for_region(hr);
}
- }
- hr->add_to_marked_bytes(marked_bytes);
// Update the live region bitmap.
if (marked_bytes > 0) {
set_bit_for_region(hr);
}
- hr->set_top_at_conc_mark_count(nextTop);
+
+ // Set the marked bytes for the current region so that
+ // it can be queried by a calling verificiation routine
+ _region_marked_bytes = marked_bytes;
+
_tot_live += hr->next_live_bytes();
_tot_used += hr->used();
- _words_done = words_done;
+ _tot_words_done = words_done;
- if (!_final) {
- ++_regions_done;
- if (_regions_done % 10 == 0) {
- double end_vtime_sec = os::elapsedVTime();
- double elapsed_vtime_sec = end_vtime_sec - _start_vtime_sec;
- if (elapsed_vtime_sec > (10.0 / 1000.0)) {
- jlong sleep_time_ms =
- (jlong) (elapsed_vtime_sec * _cm->cleanup_sleep_factor() * 1000.0);
- os::sleep(Thread::current(), sleep_time_ms, false);
- _start_vtime_sec = end_vtime_sec;
+ return false;
}
+
+ size_t region_marked_bytes() const { return _region_marked_bytes; }
+ size_t tot_words_done() const { return _tot_words_done; }
+ size_t tot_live() const { return _tot_live; }
+ size_t tot_used() const { return _tot_used; }
+};
+
+// Aggregate the counting data that was constructed concurrently
+// with marking.
+class AddToMarkedBytesClosure: public HeapRegionClosure {
+ ConcurrentMark* _cm;
+ size_t _task_num;
+ size_t _max_task_num;
+
+ bool _final;
+
+public:
+ AddToMarkedBytesClosure(ConcurrentMark *cm,
+ size_t task_num,
+ size_t max_task_num) :
+ _cm(cm),
+ _task_num(task_num),
+ _max_task_num(max_task_num),
+ _final(false)
+ {
+ assert(0 <= _task_num && _task_num < _max_task_num, "sanity");
+ if ((_max_task_num - _task_num) == 1) {
+ // Last task
+ _final = true;
}
}
+ bool doHeapRegion(HeapRegion* hr) {
+ // Adds the value in the counted marked bytes array for
+ // _task_num for region hr to the value cached in heap
+ // region itself.
+ // For the final task we also set the top at conc count
+ // for the region.
+ // The bits in the live region bitmap are set for regions
+ // that contain live data during the cleanup pause.
+
+ if (hr->continuesHumongous()) {
+ // We will ignore these here and process them when their
+ // associated "starts humongous" region is processed.
+ // Note that we cannot rely on their associated
+ // "starts humongous" region to have their bit set to 1
+ // since, due to the region chunking in the parallel region
+ // iteration, a "continues humongous" region might be visited
+ // before its associated "starts humongous".
return false;
}
- bool changed() { return _changed; }
- void reset() { _changed = false; _words_done = 0; }
- void no_yield() { _yield = false; }
- size_t words_done() { return _words_done; }
- size_t tot_live() { return _tot_live; }
- size_t tot_used() { return _tot_used; }
-};
+ int hrs_index = hr->hrs_index();
+ size_t* marked_bytes_array = _cm->count_marked_bytes_for(_task_num);
+ size_t marked_bytes = marked_bytes_array[hrs_index];
+ hr->add_to_marked_bytes(marked_bytes);
+ if (_final) {
+ HeapWord* ntams = hr->next_top_at_mark_start();
+ HeapWord* start = hr->bottom();
-void ConcurrentMark::calcDesiredRegions() {
- _region_bm.clear();
+ assert(start <= ntams && ntams <= hr->top() && hr->top() <= hr->end(),
+ "Preconditions.");
+
+ hr->set_top_at_conc_mark_count(ntams);
+ }
+
+ return false;
+ }
+};
+
+void ConcurrentMark::aggregate_all_count_data() {
_card_bm.clear();
- CalcLiveObjectsClosure calccl(false /*final*/,
- nextMarkBitMap(), this,
- &_region_bm, &_card_bm);
- G1CollectedHeap *g1h = G1CollectedHeap::heap();
- g1h->heap_region_iterate(&calccl);
- do {
- calccl.reset();
- g1h->heap_region_iterate(&calccl);
- } while (calccl.changed());
+ // Unions the per task card bitmaps into the global card bitmap,
+ // and aggregates the per task marked bytes for each region into
+ // the heap region itself.
+
+ for (int i = 0; i < _max_task_num; i += 1) {
+ BitMap& task_card_bm = count_card_bitmap_for(i);
+ _card_bm.set_union(task_card_bm);
+
+ // Update the marked bytes for each region
+ AddToMarkedBytesClosure cl(this, i, _max_task_num);
+ _g1h->heap_region_iterate(&cl);
+ }
+
+ // We're done with the accumulated per-task concurrent
+ // counting data so let's clear it for the next marking.
+ clear_all_count_data();
}
+// Final update of count data (during cleanup).
+// Adds [top_at_count, NTAMS) to the marked bytes for each
+// region. Sets the bits in the card bitmap corresponding
+// to the interval [top_at_count, top], and sets the
+// liveness bit for each region containing live data
+// in the region bitmap.
+
+class FinalCountDataUpdateClosure: public HeapRegionClosure {
+ ConcurrentMark* _cm;
+ BitMap* _region_bm;
+ BitMap* _card_bm;
+ intptr_t _bottom_card_num;
+
+ size_t _total_live_bytes;
+ size_t _total_used_bytes;
+ size_t _total_words_done;
+
+ void mark_card_num_range(intptr_t start_card_num, intptr_t last_card_num) {
+ BitMap::idx_t start_idx = start_card_num - _bottom_card_num;
+ BitMap::idx_t last_idx = last_card_num - _bottom_card_num;
+
+ // Inclusive bit range [start_idx, last_idx]. par_at_put_range
+ // is exclusive so we have to also set the bit for last_idx.
+ // Passing last_idx+1 to the clear_range would work in
+ // most cases but could trip an OOB assertion.
+
+ if ((last_idx - start_idx) > 0) {
+ _card_bm->par_at_put_range(start_idx, last_idx, true);
+ }
+ _card_bm->par_set_bit(last_idx);
+ }
+
+ // It takes a region that's not empty (i.e., it has at least one
+ // live object in it and sets its corresponding bit on the region
+ // bitmap to 1. If the region is "starts humongous" it will also set
+ // to 1 the bits on the region bitmap that correspond to its
+ // associated "continues humongous" regions.
+ void set_bit_for_region(HeapRegion* hr) {
+ assert(!hr->continuesHumongous(), "should have filtered those out");
+
+ size_t index = hr->hrs_index();
+ if (!hr->startsHumongous()) {
+ // Normal (non-humongous) case: just set the bit.
+ _region_bm->par_set_bit((BitMap::idx_t) index);
+ } else {
+ // Starts humongous case: calculate how many regions are part of
+ // this humongous region and then set the bit range. It might
+ // have been a bit more efficient to look at the object that
+ // spans these humongous regions to calculate their number from
+ // the object's size. However, it's a good idea to calculate
+ // this based on the metadata itself, and not the region
+ // contents, so that this code is not aware of what goes into
+ // the humongous regions (in case this changes in the future).
+ G1CollectedHeap* g1h = G1CollectedHeap::heap();
+ size_t end_index = index + 1;
+ while (end_index < g1h->n_regions()) {
+ HeapRegion* chr = g1h->region_at(end_index);
+ if (!chr->continuesHumongous()) break;
+ end_index += 1;
+ }
+ _region_bm->par_at_put_range((BitMap::idx_t) index,
+ (BitMap::idx_t) end_index, true);
+ }
+ }
+
+ public:
+ FinalCountDataUpdateClosure(ConcurrentMark* cm,
+ BitMap* region_bm,
+ BitMap* card_bm) :
+ _cm(cm), _region_bm(region_bm), _card_bm(card_bm),
+ _total_words_done(0), _total_live_bytes(0), _total_used_bytes(0)
+ {
+ _bottom_card_num =
+ intptr_t(uintptr_t(G1CollectedHeap::heap()->reserved_region().start()) >>
+ CardTableModRefBS::card_shift);
+ }
+
+ bool doHeapRegion(HeapRegion* hr) {
+
+ if (hr->continuesHumongous()) {
+ // We will ignore these here and process them when their
+ // associated "starts humongous" region is processed (see
+ // set_bit_for_heap_region()). Note that we cannot rely on their
+ // associated "starts humongous" region to have their bit set to
+ // 1 since, due to the region chunking in the parallel region
+ // iteration, a "continues humongous" region might be visited
+ // before its associated "starts humongous".
+ return false;
+ }
+
+ HeapWord* start = hr->top_at_conc_mark_count();
+ HeapWord* ntams = hr->next_top_at_mark_start();
+ HeapWord* top = hr->top();
+
+ assert(hr->bottom() <= start && start <= hr->end() &&
+ hr->bottom() <= ntams && ntams <= hr->end(), "Preconditions.");
+
+ size_t words_done = ntams - hr->bottom();
+
+ intptr_t start_card_num = intptr_t(uintptr_t(start) >> CardTableModRefBS::card_shift);
+ intptr_t last_card_num = intptr_t(uintptr_t(top) >> CardTableModRefBS::card_shift);
+
+
+ if (start < ntams) {
+ // Region was changed between remark and cleanup pauses
+ // We need to add (ntams - start) to the marked bytes
+ // for this region, and set bits for the range
+ // [ card_num(start), card_num(ntams) ) in the
+ // card bitmap.
+ size_t live_bytes = (ntams - start) * HeapWordSize;
+ hr->add_to_marked_bytes(live_bytes);
+
+ // Record the new top at conc count
+ hr->set_top_at_conc_mark_count(ntams);
+
+ // The setting of the bits card bitmap takes place below
+ }
+
+ // Mark the allocated-since-marking portion...
+ if (ntams < top) {
+ // This definitely means the region has live objects.
+ set_bit_for_region(hr);
+ }
+
+ // Now set the bits for [start, top]
+ mark_card_num_range(start_card_num, last_card_num);
+
+ // Set the bit for the region if it contains live data
+ if (hr->next_marked_bytes() > 0) {
+ set_bit_for_region(hr);
+ }
+
+ _total_words_done += words_done;
+ _total_used_bytes += hr->used();
+ _total_live_bytes += hr->next_marked_bytes();
+
+ return false;
+ }
+
+ size_t total_words_done() const { return _total_words_done; }
+ size_t total_live_bytes() const { return _total_live_bytes; }
+ size_t total_used_bytes() const { return _total_used_bytes; }
+};
+
+// Heap region closure used for verifying the counting data
+// that was accumulated concurrently and aggregated during
+// the remark pause. This closure is applied to the heap
+// regions during the STW cleanup pause.
+
+class VerifyLiveObjectDataHRClosure: public HeapRegionClosure {
+ ConcurrentMark* _cm;
+ CalcLiveObjectsClosure _calc_cl;
+ BitMap* _region_bm; // Region BM to be verified
+ BitMap* _card_bm; // Card BM to be verified
+ bool _verbose; // verbose output?
+
+ BitMap* _exp_region_bm; // Expected Region BM values
+ BitMap* _exp_card_bm; // Expected card BM values
+
+ intptr_t _bottom_card_num; // Used for calculatint bitmap indices
+
+ int _failures;
+
+public:
+ VerifyLiveObjectDataHRClosure(ConcurrentMark* cm,
+ BitMap* region_bm,
+ BitMap* card_bm,
+ BitMap* exp_region_bm,
+ BitMap* exp_card_bm,
+ bool verbose) :
+ _cm(cm),
+ _calc_cl(_cm->nextMarkBitMap(), _cm, exp_region_bm, exp_card_bm),
+ _region_bm(region_bm), _card_bm(card_bm), _verbose(verbose),
+ _exp_region_bm(exp_region_bm), _exp_card_bm(exp_card_bm),
+ _failures(0)
+ {
+ _bottom_card_num =
+ intptr_t(uintptr_t(G1CollectedHeap::heap()->reserved_region().start()) >>
+ CardTableModRefBS::card_shift);
+ }
+
+ int failures() const { return _failures; }
+
+ bool doHeapRegion(HeapRegion* hr) {
+ if (hr->continuesHumongous()) {
+ // We will ignore these here and process them when their
+ // associated "starts humongous" region is processed (see
+ // set_bit_for_heap_region()). Note that we cannot rely on their
+ // associated "starts humongous" region to have their bit set to
+ // 1 since, due to the region chunking in the parallel region
+ // iteration, a "continues humongous" region might be visited
+ // before its associated "starts humongous".
+ return false;
+ }
+
+ // Call the CalcLiveObjectsClosure to walk the marking bitmap for
+ // this region and set the corresponding bits in the expected region
+ // and card bitmaps.
+ bool res = _calc_cl.doHeapRegion(hr);
+ assert(res == false, "should be continuing");
+
+ // Note that the calculated count data could be a subset of the
+ // count data that was accumlated during marking. See the comment
+ // in G1ParCopyHelper::copy_to_survivor space for an explanation
+ // why.
+
+ if (_verbose) {
+ gclog_or_tty->print("Region %d: bottom: "PTR_FORMAT", ntams: "
+ PTR_FORMAT", top: "PTR_FORMAT", end: "PTR_FORMAT,
+ hr->hrs_index(), hr->bottom(), hr->next_top_at_mark_start(),
+ hr->top(), hr->end());
+ gclog_or_tty->print_cr(", marked_bytes: calc/actual "SIZE_FORMAT"/"SIZE_FORMAT,
+ _calc_cl.region_marked_bytes(),
+ hr->next_marked_bytes());
+ }
+
+ // Verify that _top_at_conc_count == ntams
+ if (hr->top_at_conc_mark_count() != hr->next_top_at_mark_start()) {
+ if (_verbose) {
+ gclog_or_tty->print_cr("Region %d: top at conc count incorrect: expected "
+ PTR_FORMAT", actual: "PTR_FORMAT,
+ hr->hrs_index(), hr->next_top_at_mark_start(),
+ hr->top_at_conc_mark_count());
+ }
+ _failures += 1;
+ }
+
+ // Verify the marked bytes for this region.
+ size_t exp_marked_bytes = _calc_cl.region_marked_bytes();
+ size_t act_marked_bytes = hr->next_marked_bytes();
+
+ // We're OK if actual marked bytes >= expected.
+ if (exp_marked_bytes > act_marked_bytes) {
+ if (_verbose) {
+ gclog_or_tty->print_cr("Region %d: marked bytes mismatch: expected: "
+ SIZE_FORMAT", actual: "SIZE_FORMAT,
+ hr->hrs_index(), exp_marked_bytes, act_marked_bytes);
+ }
+ _failures += 1;
+ }
+
+ // Verify the bit, for this region, in the actual and expected
+ // (which was just calculated) region bit maps.
+ // We're not OK if the expected bit is set and the actual is not set.
+ BitMap::idx_t index = (BitMap::idx_t)hr->hrs_index();
+
+ bool expected = _exp_region_bm->at(index);
+ bool actual = _region_bm->at(index);
+ if (expected && !actual) {
+ if (_verbose) {
+ gclog_or_tty->print_cr("Region %d: region bitmap mismatch: expected: %d, actual: %d",
+ hr->hrs_index(), expected, actual);
+ }
+ _failures += 1;
+ }
+
+ // Verify that the card bit maps for the cards spanned by the current
+ // region match. The set of offsets that have set bits in the expected
+ // bitmap should be a subset of the offsets with set bits from the actual
+ // calculated card bitmap.
+ // Again it's more important that if the expected bit is set then the
+ // actual bit be set.
+ intptr_t start_card_num =
+ intptr_t(uintptr_t(hr->bottom()) >> CardTableModRefBS::card_shift);
+ intptr_t top_card_num =
+ intptr_t(uintptr_t(hr->top()) >> CardTableModRefBS::card_shift);
+
+ BitMap::idx_t start_idx = start_card_num - _bottom_card_num;
+ BitMap::idx_t end_idx = top_card_num - _bottom_card_num;
+
+ for (BitMap::idx_t i = start_idx; i < end_idx; i+=1) {
+ expected = _exp_card_bm->at(i);
+ actual = _card_bm->at(i);
+
+ if (expected && !actual) {
+ if (_verbose) {
+ gclog_or_tty->print_cr("Region %d: card bitmap mismatch at idx %d: expected: %d, actual: %d",
+ hr->hrs_index(), i, expected, actual);
+ }
+ _failures += 1;
+ }
+ }
+ if (_failures) {
+ // Stop iteration?
+ return true;
+ }
+
+ return false;
+ }
+};
+
+class Mux2HRClosure: public HeapRegionClosure {
+ HeapRegionClosure* _cl1;
+ HeapRegionClosure* _cl2;
+
+public:
+ Mux2HRClosure(HeapRegionClosure *c1, HeapRegionClosure *c2) : _cl1(c1), _cl2(c2) { }
+ bool doHeapRegion(HeapRegion* hr) {
+ bool res1 = _cl1->doHeapRegion(hr);
+ bool res2 = _cl2->doHeapRegion(hr);
+
+ // Only continue if both return false;
+ return res1 || res2;
+ }
+};
+
class G1ParFinalCountTask: public AbstractGangTask {
protected:
G1CollectedHeap* _g1h;
CMBitMap* _bm;
size_t _n_workers;
size_t *_live_bytes;
size_t *_used_bytes;
- BitMap* _region_bm;
- BitMap* _card_bm;
+
+ BitMap* _actual_region_bm;
+ BitMap* _actual_card_bm;
+
+ BitMap _expected_region_bm;
+ BitMap _expected_card_bm;
+
+ int _failures;
+
public:
G1ParFinalCountTask(G1CollectedHeap* g1h, CMBitMap* bm,
BitMap* region_bm, BitMap* card_bm)
- : AbstractGangTask("G1 final counting"), _g1h(g1h),
- _bm(bm), _region_bm(region_bm), _card_bm(card_bm) {
+ : AbstractGangTask("G1 final counting"),
+ _g1h(g1h), _bm(bm),
+ _actual_region_bm(region_bm), _actual_card_bm(card_bm),
+ _expected_region_bm(0, false), _expected_card_bm(0, false),
+ _failures(0)
+ {
if (ParallelGCThreads > 0) {
_n_workers = _g1h->workers()->total_workers();
} else {
_n_workers = 1;
}
+
_live_bytes = NEW_C_HEAP_ARRAY(size_t, _n_workers);
_used_bytes = NEW_C_HEAP_ARRAY(size_t, _n_workers);
+
+ if (VerifyDuringGC) {
+ _expected_card_bm.resize(_actual_card_bm->size(), false);
+ _expected_region_bm.resize(_actual_region_bm->size(), false);
+ }
}
~G1ParFinalCountTask() {
+ if (VerifyDuringGC) {
+ _expected_region_bm.resize(0);
+ _expected_card_bm.resize(0);
+ }
FREE_C_HEAP_ARRAY(size_t, _live_bytes);
FREE_C_HEAP_ARRAY(size_t, _used_bytes);
}
void work(int i) {
- CalcLiveObjectsClosure calccl(true /*final*/,
- _bm, _g1h->concurrent_mark(),
- _region_bm, _card_bm);
- calccl.no_yield();
+
+ FinalCountDataUpdateClosure final_update_cl(_g1h->concurrent_mark(),
+ _actual_region_bm, _actual_card_bm);
+
+ VerifyLiveObjectDataHRClosure verify_cl(_g1h->concurrent_mark(),
+ _actual_region_bm, _actual_card_bm,
+ &_expected_region_bm,
+ &_expected_card_bm,
+ true /* verbose */);
+
+ Mux2HRClosure update_and_verify_cl(&final_update_cl, &verify_cl);
+
+ HeapRegionClosure* hr_cl = &final_update_cl;
+ if (VerifyDuringGC) {
+ hr_cl = &update_and_verify_cl;
+ }
+
if (G1CollectedHeap::use_parallel_gc_threads()) {
- _g1h->heap_region_par_iterate_chunked(&calccl, i,
+ _g1h->heap_region_par_iterate_chunked(hr_cl, i,
HeapRegion::FinalCountClaimValue);
} else {
- _g1h->heap_region_iterate(&calccl);
+ _g1h->heap_region_iterate(hr_cl);
}
- assert(calccl.complete(), "Shouldn't have yielded!");
assert((size_t) i < _n_workers, "invariant");
- _live_bytes[i] = calccl.tot_live();
- _used_bytes[i] = calccl.tot_used();
+ _live_bytes[i] = final_update_cl.total_live_bytes();
+ _used_bytes[i] = final_update_cl.total_used_bytes();
+
+ if (VerifyDuringGC) {
+ _failures += verify_cl.failures();
+ }
}
+
size_t live_bytes() {
size_t live_bytes = 0;
for (size_t i = 0; i < _n_workers; ++i)
live_bytes += _live_bytes[i];
return live_bytes;
}
+
size_t used_bytes() {
size_t used_bytes = 0;
for (size_t i = 0; i < _n_workers; ++i)
used_bytes += _used_bytes[i];
return used_bytes;
}
+
+ int failures() const { return _failures; }
};
class G1ParNoteEndTask;
class G1NoteEndOfConcMarkClosure : public HeapRegionClosure {
@@ -1705,30 +2131,39 @@
double start = os::elapsedTime();
HeapRegionRemSet::reset_for_cleanup_tasks();
+ // Clear the global region bitmap - it will be filled as part
+ // of the final counting task.
+ _region_bm.clear();
+
// Do counting once more with the world stopped for good measure.
G1ParFinalCountTask g1_par_count_task(g1h, nextMarkBitMap(),
&_region_bm, &_card_bm);
+
if (G1CollectedHeap::use_parallel_gc_threads()) {
- assert(g1h->check_heap_region_claim_values(
- HeapRegion::InitialClaimValue),
+ assert(g1h->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
"sanity check");
int n_workers = g1h->workers()->total_workers();
g1h->set_par_threads(n_workers);
g1h->workers()->run_task(&g1_par_count_task);
g1h->set_par_threads(0);
- assert(g1h->check_heap_region_claim_values(
- HeapRegion::FinalCountClaimValue),
+ assert(g1h->check_heap_region_claim_values(HeapRegion::FinalCountClaimValue),
"sanity check");
} else {
g1_par_count_task.work(0);
}
+ // Verify that there were no verification failures of
+ // the live counting data.
+ if (VerifyDuringGC) {
+ assert(g1_par_count_task.failures() == 0, "Unexpected failures");
+ }
+
size_t known_garbage_bytes =
g1_par_count_task.used_bytes() - g1_par_count_task.live_bytes();
g1p->set_known_garbage_bytes(known_garbage_bytes);
size_t start_used_bytes = g1h->used();
@@ -1927,11 +2362,14 @@
CMBitMap* _bitMap;
public:
G1CMKeepAliveClosure(G1CollectedHeap* g1, ConcurrentMark* cm,
CMBitMap* bitMap) :
_g1(g1), _cm(cm),
- _bitMap(bitMap) {}
+ _bitMap(bitMap)
+ {
+ assert(Thread::current()->is_VM_thread(), "otherwise fix worker id");
+ }
virtual void do_oop(narrowOop* p) { do_oop_work(p); }
virtual void do_oop( oop* p) { do_oop_work(p); }
template <class T> void do_oop_work(T* p) {
@@ -1944,10 +2382,13 @@
p, (void*) obj);
}
if (_g1->is_in_g1_reserved(addr) && _g1->is_obj_ill(obj)) {
_bitMap->mark(addr);
+ // Update the task specific count data for obj
+ _cm->add_to_count_data_for(obj, 0 /* worker_i */);
+
_cm->mark_stack_push(obj);
}
}
};
@@ -2594,10 +3035,13 @@
"marked", (void*) obj);
}
// we need to mark it first
if (_nextMarkBitMap->parMark(objAddr)) {
+ // Update the task specific count data for obj
+ add_to_count_data_for(obj, hr, 0 /* worker_i */);
+
// No OrderAccess:store_load() is needed. It is implicit in the
// CAS done in parMark(objAddr) above
HeapWord* finger = _finger;
if (objAddr < finger) {
if (verbose_high()) {
@@ -2840,10 +3284,192 @@
// Clear any partial regions from the CMTasks
_tasks[i]->clear_aborted_region();
}
}
+// Clear the per-worker arrays used to store the per-region counting data
+void ConcurrentMark::clear_all_count_data() {
+ assert(SafepointSynchronize::is_at_safepoint() ||
+ !Universe::is_fully_initialized(), "must be");
+
+ int max_regions = _g1h->max_regions();
+
+ assert(_max_task_num != 0, "unitialized");
+ assert(_count_card_bitmaps != NULL, "uninitialized");
+ assert(_count_marked_bytes != NULL, "uninitialized");
+
+ for (int i = 0; i < _max_task_num; i += 1) {
+ BitMap& task_card_bm = count_card_bitmap_for(i);
+ size_t* marked_bytes_array = count_marked_bytes_for(i);
+
+ assert(task_card_bm.size() == _card_bm.size(), "size mismatch");
+ assert(marked_bytes_array != NULL, "uninitialized");
+
+ for (int j = 0; j < max_regions; j++) {
+ marked_bytes_array[j] = 0;
+ }
+ task_card_bm.clear();
+ }
+}
+
+// Adds the given region to the counting data structures
+// for the given task id.
+void ConcurrentMark::add_to_count_data_for(MemRegion mr,
+ HeapRegion* hr,
+ int worker_i) {
+ G1CollectedHeap* g1h = _g1h;
+ HeapWord* start = mr.start();
+ HeapWord* last = mr.last();
+ size_t index = hr->hrs_index();
+
+ assert(!hr->continuesHumongous(), "should not be HC region");
+ assert(hr == g1h->heap_region_containing(start), "sanity");
+ assert(hr == g1h->heap_region_containing(mr.last()), "sanity");
+ assert(0 <= worker_i && worker_i < _max_task_num, "oob");
+
+ BitMap& task_card_bm = count_card_bitmap_for(worker_i);
+ size_t* marked_bytes_array = count_marked_bytes_for(worker_i);
+
+ // Below, the term "card num" means the result of shifting an address
+ // by the card shift -- address 0 corresponds to card number 0. One
+ // must subtract the card num of the bottom of the heap to obtain a
+ // card table index.
+
+ intptr_t start_card_num =
+ intptr_t(uintptr_t(start) >> CardTableModRefBS::card_shift);
+ intptr_t last_card_num =
+ intptr_t(uintptr_t(last) >> CardTableModRefBS::card_shift);
+
+ intptr_t bottom_card_num =
+ intptr_t(uintptr_t(G1CollectedHeap::heap()->reserved_region().start()) >>
+ CardTableModRefBS::card_shift);
+
+ BitMap::idx_t start_idx = start_card_num - bottom_card_num;
+ BitMap::idx_t last_idx = last_card_num - bottom_card_num;
+
+ // The card bitmap is task/worker specific => no need to use 'par' routines.
+ // Inclusive bit range [start_idx, last_idx]. set_range is exclusive
+ // so we have to also explicitly set the bit for last_idx.
+ // Passing last_idx+1 to the clear_range would work in most cases
+ // but could trip an OOB assertion.
+
+ if ((last_idx - start_idx) > 0) {
+ task_card_bm.set_range(start_idx, last_idx);
+ }
+ task_card_bm.set_bit(last_idx);
+
+ // Add to the task local marked bytes for this region.
+ marked_bytes_array[index] += mr.byte_size();
+}
+
+void ConcurrentMark::add_to_count_data_for(oop obj, HeapRegion* hr, int worker_i) {
+ MemRegion mr((HeapWord*)obj, obj->size());
+ add_to_count_data_for(mr, hr, worker_i);
+}
+
+void ConcurrentMark::add_to_count_data_for(MemRegion mr, int worker_i) {
+ HeapRegion* hr = _g1h->heap_region_containing(mr.start());
+ add_to_count_data_for(mr, hr, worker_i);
+}
+
+void ConcurrentMark::add_to_count_data_for(oop obj, int worker_i) {
+ MemRegion mr((HeapWord*)obj, obj->size());
+ add_to_count_data_for(mr, worker_i);
+}
+
+// Updates the counting data with liveness info recorded for a
+// region (typically a GCLab).
+void ConcurrentMark::add_to_count_data_for_region(MemRegion lab_mr,
+ BitMap* lab_card_bm,
+ intptr_t lab_bottom_card_num,
+ size_t lab_marked_bytes,
+ int worker_i) {
+ HeapRegion* hr = _g1h->heap_region_containing(lab_mr.start());
+
+ BitMap& task_card_bm = count_card_bitmap_for(worker_i);
+ size_t* marked_bytes_array = count_marked_bytes_for(worker_i);
+
+ // Below, the term "card num" means the result of shifting an address
+ // by the card shift -- address 0 corresponds to card number 0. One
+ // must subtract the card num of the bottom of the heap to obtain a
+ // card table index.
+
+ intptr_t heap_bottom_card_num =
+ intptr_t(uintptr_t(G1CollectedHeap::heap()->reserved_region().start()) >>
+ CardTableModRefBS::card_shift);
+
+ assert(intptr_t(uintptr_t(lab_mr.start()) >> CardTableModRefBS::card_shift) == lab_bottom_card_num,
+ "sanity");
+
+ // We have to map the indices of set bits in lab_card_bm, using
+ // lab_bottom_card_num, to indices the card bitmap for the given task.
+
+ BitMap::idx_t end_idx = lab_card_bm->size();
+ BitMap::idx_t start_idx = lab_card_bm->get_next_one_offset(0, end_idx);
+ while (start_idx < end_idx) {
+ assert(lab_card_bm->at(start_idx), "should be set");
+
+ intptr_t lab_card_num = lab_bottom_card_num + start_idx;
+ BitMap::idx_t card_bm_idx = lab_card_num - heap_bottom_card_num;
+
+ task_card_bm.set_bit(card_bm_idx);
+
+ // Get the offset of the next set bit
+ start_idx = lab_card_bm->get_next_one_offset(start_idx+1, end_idx);
+ }
+
+ // Now add to the marked bytes
+ marked_bytes_array[hr->hrs_index()] += lab_marked_bytes;
+}
+
+void ConcurrentMark::clear_count_data_for_heap_region(HeapRegion* hr) {
+ // Clears the count data for the given region from _all_ of
+ // the per-task counting data structures.
+
+ MemRegion used_region = hr->used_region();
+ HeapWord* start = used_region.start();
+ HeapWord* last = used_region.last();
+ size_t hr_index = hr->hrs_index();
+
+ intptr_t bottom_card_num =
+ intptr_t(uintptr_t(G1CollectedHeap::heap()->reserved_region().start()) >>
+ CardTableModRefBS::card_shift);
+
+ intptr_t start_card_num =
+ intptr_t(uintptr_t(start) >> CardTableModRefBS::card_shift);
+ intptr_t last_card_num =
+ intptr_t(uintptr_t(last) >> CardTableModRefBS::card_shift);
+
+ BitMap::idx_t start_idx = start_card_num - bottom_card_num;
+ BitMap::idx_t last_idx = last_card_num - bottom_card_num;
+
+ size_t used_region_bytes = used_region.byte_size();
+ size_t marked_bytes = 0;
+
+ for (int i=0; i < _max_task_num; i += 1) {
+ BitMap& task_card_bm = count_card_bitmap_for(i);
+ size_t* marked_bytes_array = count_marked_bytes_for(i);
+
+ marked_bytes += marked_bytes_array[hr_index];
+ // clear the amount of marked bytes in the task array for this
+ // region
+ marked_bytes_array[hr_index] = 0;
+
+ // Clear the inclusive range [start_idx, last_idx] from the
+ // card bitmap. The clear_range routine is exclusive so we
+ // need to also explicitly clear the bit at last_idx.
+ // Passing last_idx+1 to the clear_range would work in
+ // most cases but could trip an OOB assertion.
+
+ if ((last_idx - start_idx) > 0) {
+ task_card_bm.clear_range(start_idx, last_idx);
+ }
+ task_card_bm.clear_bit(last_idx);
+ }
+ // We could assert here that marked_bytes == used_region_bytes
+}
+
void ConcurrentMark::print_stats() {
if (verbose_stats()) {
gclog_or_tty->print_cr("---------------------------------------------------------------------");
for (size_t i = 0; i < _active_tasks; ++i) {
_tasks[i]->print_stats();
@@ -2945,10 +3571,13 @@
HeapRegion* hr = _g1h->heap_region_containing(obj);
if (hr != NULL) {
if (hr->in_collection_set()) {
if (_g1h->is_obj_ill(obj)) {
_bm->mark((HeapWord*)obj);
+ // Update the task specific count data for object
+ _cm->add_to_count_data_for(obj, hr, 0 /* worker_i */);
+
if (!push(obj)) {
gclog_or_tty->print_cr("Setting abort in CSMarkOopClosure because push failed.");
set_abort();
}
}
@@ -3026,18 +3655,22 @@
bool completed() { return _completed; }
};
class ClearMarksInHRClosure: public HeapRegionClosure {
+ ConcurrentMark* _cm;
CMBitMap* _bm;
public:
- ClearMarksInHRClosure(CMBitMap* bm): _bm(bm) { }
+ ClearMarksInHRClosure(ConcurrentMark* cm, CMBitMap* bm):
+ _cm(cm), _bm(bm)
+ { }
bool doHeapRegion(HeapRegion* r) {
if (!r->used_region().is_empty() && !r->evacuation_failed()) {
- MemRegion usedMR = r->used_region();
_bm->clearRange(r->used_region());
+ // Need to remove values from the count info
+ _cm->clear_count_data_for_heap_region(r);
}
return false;
}
};
@@ -3059,11 +3692,11 @@
}
double end_time = os::elapsedTime();
double elapsed_time_ms = (end_time - start) * 1000.0;
g1h->g1_policy()->record_mark_closure_time(elapsed_time_ms);
- ClearMarksInHRClosure clr(nextMarkBitMap());
+ ClearMarksInHRClosure clr(this, nextMarkBitMap());
g1h->collection_set_iterate(&clr);
}
// The next two methods deal with the following optimisation. Some
// objects are gray by being marked and located above the finger. If
@@ -3201,14 +3834,13 @@
}
gclog_or_tty->print_cr(" Total stop_world time = %8.2f s.",
(_init_times.sum() + _remark_times.sum() +
_cleanup_times.sum())/1000.0);
gclog_or_tty->print_cr(" Total concurrent time = %8.2f s "
- "(%8.2f s marking, %8.2f s counting).",
+ "(%8.2f s marking).",
cmThread()->vtime_accum(),
- cmThread()->vtime_mark_accum(),
- cmThread()->vtime_count_accum());
+ cmThread()->vtime_mark_accum());
}
void ConcurrentMark::print_worker_threads_on(outputStream* st) const {
_parallel_workers->print_worker_threads_on(st);
}