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8178105: Switch mark bitmaps during Remark

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Reviewed-by: sjohanss, sangheki
This commit is contained in:
Thomas Schatzl 2018-04-18 11:36:48 +02:00
parent 33b921f25d
commit 7c09cf644b
3 changed files with 85 additions and 21 deletions
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84
src/hotspot/share/gc/g1/g1ConcurrentMark.cpp
View File

@ -1012,6 +1012,8 @@ class G1UpdateRemSetTrackingBeforeRebuild : public HeapRegionClosure {
G1CollectedHeap* _g1h;
G1ConcurrentMark* _cm;
G1PrintRegionLivenessInfoClosure _cl;
uint _num_regions_selected_for_rebuild; // The number of regions actually selected for rebuild.
void update_remset_before_rebuild(HeapRegion * hr) {
@ -1025,12 +1027,56 @@ class G1UpdateRemSetTrackingBeforeRebuild : public HeapRegionClosure {
_cm->update_top_at_rebuild_start(hr);
}
void distribute_marked_bytes(HeapRegion* hr, size_t marked_words) {
uint const region_idx = hr->hrm_index();
uint num_regions_in_humongous = (uint)G1CollectedHeap::humongous_obj_size_in_regions(marked_words);
for (uint i = region_idx; i < (region_idx + num_regions_in_humongous); i++) {
HeapRegion* const r = _g1h->region_at(i);
size_t const words_to_add = MIN2(HeapRegion::GrainWords, marked_words);
assert(words_to_add > 0, "Out of space to distribute before end of humongous object in region %u (starts %u)", i, region_idx);
log_trace(gc, marking)("Adding " SIZE_FORMAT " words to humongous region %u (%s)",
words_to_add, i, r->get_type_str());
r->add_to_marked_bytes(words_to_add * HeapWordSize);
marked_words -= words_to_add;
}
assert(marked_words == 0,
SIZE_FORMAT " words left after distributing space across %u regions",
marked_words, num_regions_in_humongous);
}
void update_marked_bytes(HeapRegion* hr) {
uint const region_idx = hr->hrm_index();
size_t marked_words = _cm->liveness(region_idx);
// The marking attributes the object's size completely to the humongous starts
// region. We need to distribute this value across the entire set of regions a
// humongous object spans.
if (hr->is_humongous()) {
assert(hr->is_starts_humongous() || marked_words == 0,
"Should not have marked words " SIZE_FORMAT " in non-starts humongous region %u (%s)",
marked_words, region_idx, hr->get_type_str());
if (marked_words > 0) {
distribute_marked_bytes(hr, marked_words);
}
} else {
log_trace(gc, marking)("Adding " SIZE_FORMAT " words to region %u (%s)", marked_words, region_idx, hr->get_type_str());
hr->add_to_marked_bytes(marked_words * HeapWordSize);
}
}
public:
G1UpdateRemSetTrackingBeforeRebuild(G1CollectedHeap* g1h, G1ConcurrentMark* cm) :
_g1h(g1h), _cm(cm), _num_regions_selected_for_rebuild(0) { }
_g1h(g1h), _cm(cm), _cl("Post-Marking"), _num_regions_selected_for_rebuild(0) { }
virtual bool do_heap_region(HeapRegion* r) {
update_remset_before_rebuild(r);
update_marked_bytes(r);
if (log_is_enabled(Trace, gc, liveness)) {
_cl.do_heap_region(r);
}
r->note_end_of_marking();
return false;
}
@ -1087,6 +1133,8 @@ void G1ConcurrentMark::remark() {
flush_all_task_caches();
}
// Install newly created mark bitmap as "prev".
swap_mark_bitmaps();
{
GCTraceTime(Debug, gc, phases)("Update Remembered Set Tracking Before Rebuild");
G1UpdateRemSetTrackingBeforeRebuild cl(_g1h, this);
@ -1095,7 +1143,7 @@ void G1ConcurrentMark::remark() {
_g1h->num_regions(), cl.num_selected_for_rebuild());
}
verify_during_pause(G1HeapVerifier::G1VerifyRemark, VerifyOption_G1UseNextMarking, "Remark after");
verify_during_pause(G1HeapVerifier::G1VerifyRemark, VerifyOption_G1UsePrevMarking, "Remark after");
assert(!restart_for_overflow(), "sanity");
// Completely reset the marking state since marking completed
@ -1113,7 +1161,7 @@ void G1ConcurrentMark::remark() {
{
GCTraceTime(Debug, gc, phases)("Report Object Count");
report_object_count();
report_object_count(mark_finished);
}
// Statistics
@ -1151,8 +1199,6 @@ class G1CleanupTask : public AbstractGangTask {
const uint humongous_regions_removed() { return _humongous_regions_removed; }
bool do_heap_region(HeapRegion *hr) {
hr->note_end_of_marking();
if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young() && !hr->is_archive()) {
_freed_bytes += hr->used();
hr->set_containing_set(NULL);
@ -1247,7 +1293,7 @@ void G1ConcurrentMark::cleanup() {
double start = os::elapsedTime();
verify_during_pause(G1HeapVerifier::G1VerifyCleanup, VerifyOption_G1UseNextMarking, "Cleanup before");
verify_during_pause(G1HeapVerifier::G1VerifyCleanup, VerifyOption_G1UsePrevMarking, "Cleanup before");
{
GCTraceTime(Debug, gc, phases)("Update Remembered Set Tracking After Rebuild");
@ -1260,8 +1306,6 @@ void G1ConcurrentMark::cleanup() {
_g1h->heap_region_iterate(&cl);
}
// Install newly created mark bitmap as "prev".
swap_mark_bitmaps();
{
GCTraceTime(Debug, gc, phases)("Reclaim Empty Regions");
reclaim_empty_regions();
@ -1629,10 +1673,32 @@ void G1ConcurrentMark::weak_refs_work(bool clear_all_soft_refs) {
}
}
void G1ConcurrentMark::report_object_count() {
// When sampling object counts, we already swapped the mark bitmaps, so we need to use
// the prev bitmap determining liveness.
class G1ObjectCountIsAliveClosure: public BoolObjectClosure {
G1CollectedHeap* _g1;
public:
G1ObjectCountIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) { }
bool do_object_b(oop obj) {
HeapWord* addr = (HeapWord*)obj;
return addr != NULL &&
(!_g1->is_in_g1_reserved(addr) || !_g1->is_obj_dead(obj));
}
};
void G1ConcurrentMark::report_object_count(bool mark_completed) {
// Depending on the completion of the marking liveness needs to be determined
// using either the next or prev bitmap.
if (mark_completed) {
G1ObjectCountIsAliveClosure is_alive(_g1h);
_gc_tracer_cm->report_object_count_after_gc(&is_alive);
} else {
G1CMIsAliveClosure is_alive(_g1h);
_gc_tracer_cm->report_object_count_after_gc(&is_alive);
}
}
void G1ConcurrentMark::swap_mark_bitmaps() {
G1CMBitMap* temp = _prev_mark_bitmap;

2
src/hotspot/share/gc/g1/g1ConcurrentMark.hpp
View File

@ -367,7 +367,7 @@ class G1ConcurrentMark : public CHeapObj<mtGC> {
void weak_refs_work_parallel_part(BoolObjectClosure* is_alive, bool purged_classes);
void weak_refs_work(bool clear_all_soft_refs);
void report_object_count();
void report_object_count(bool mark_completed);
void swap_mark_bitmaps();

16
src/hotspot/share/gc/g1/g1RemSet.cpp
View File

@ -844,7 +844,7 @@ class G1RebuildRemSetTask: public AbstractGangTask {
assert(hr->top() == top_at_mark_start || hr->top() == top_at_rebuild_start,
"More than one object in the humongous region?");
humongous_obj->oop_iterate(&_update_cl, mr);
return top_at_mark_start != hr->bottom() ? mr.byte_size() : 0;
return top_at_mark_start != hr->bottom() ? mr.intersection(MemRegion((HeapWord*)humongous_obj, humongous_obj->size())).byte_size() : 0;
} else {
return 0;
}
@ -883,7 +883,7 @@ public:
size_t total_marked_bytes = 0;
size_t const chunk_size_in_words = G1RebuildRemSetChunkSize / HeapWordSize;
HeapWord* const top_at_mark_start = hr->next_top_at_mark_start();
HeapWord* const top_at_mark_start = hr->prev_top_at_mark_start();
HeapWord* cur = hr->bottom();
while (cur < hr->end()) {
@ -900,7 +900,7 @@ public:
}
const Ticks start = Ticks::now();
size_t marked_bytes = rebuild_rem_set_in_region(_cm->next_mark_bitmap(),
size_t marked_bytes = rebuild_rem_set_in_region(_cm->prev_mark_bitmap(),
top_at_mark_start,
top_at_rebuild_start,
hr,
@ -923,7 +923,6 @@ public:
p2i(top_at_rebuild_start));
if (marked_bytes > 0) {
hr->add_to_marked_bytes(marked_bytes);
total_marked_bytes += marked_bytes;
}
cur += chunk_size_in_words;
@ -937,12 +936,11 @@ public:
// Simply filter out those regions. We can not just use region type because there
// might have already been new allocations into these regions.
DEBUG_ONLY(HeapWord* const top_at_rebuild_start = _cm->top_at_rebuild_start(region_idx);)
assert(!hr->is_old() ||
top_at_rebuild_start == NULL ||
total_marked_bytes == _cm->liveness(region_idx) * HeapWordSize,
"Marked bytes " SIZE_FORMAT " for region %u (%s) in [bottom, TAMS) do not match liveness during mark " SIZE_FORMAT " "
assert(top_at_rebuild_start == NULL ||
total_marked_bytes == hr->marked_bytes(),
"Marked bytes " SIZE_FORMAT " for region %u (%s) in [bottom, TAMS) do not match calculated marked bytes " SIZE_FORMAT " "
"(" PTR_FORMAT " " PTR_FORMAT " " PTR_FORMAT ")",
total_marked_bytes, hr->hrm_index(), hr->get_type_str(), _cm->liveness(region_idx) * HeapWordSize,
total_marked_bytes, hr->hrm_index(), hr->get_type_str(), hr->marked_bytes(),
p2i(hr->bottom()), p2i(top_at_mark_start), p2i(top_at_rebuild_start));
// Abort state may have changed after the yield check.
return _cm->has_aborted();