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android / platform / libcore / 66e3caaf9dcb14cf80fc8fdaa0909a2884671539 / . / hotspot / src / share / vm / gc_implementation / g1 / g1RemSet.cpp
blob: 6c79abcf8ba8e35d2ad44951a2e5129e93adccfa [file] [log] [blame]
/*
* Copyright (c) 2001, 2010, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include "incls/_precompiled.incl"
#include "incls/_g1RemSet.cpp.incl"
#define CARD_REPEAT_HISTO 0
#if CARD_REPEAT_HISTO
static size_t ct_freq_sz;
static jbyte* ct_freq = NULL;
void init_ct_freq_table(size_t heap_sz_bytes) {
if (ct_freq == NULL) {
ct_freq_sz = heap_sz_bytes/CardTableModRefBS::card_size;
ct_freq = new jbyte[ct_freq_sz];
for (size_t j = 0; j < ct_freq_sz; j++) ct_freq[j] = 0;
}
}
void ct_freq_note_card(size_t index) {
assert(0 <= index && index < ct_freq_sz, "Bounds error.");
if (ct_freq[index] < 100) { ct_freq[index]++; }
}
static IntHistogram card_repeat_count(10, 10);
void ct_freq_update_histo_and_reset() {
for (size_t j = 0; j < ct_freq_sz; j++) {
card_repeat_count.add_entry(ct_freq[j]);
ct_freq[j] = 0;
}
}
#endif
class IntoCSOopClosure: public OopsInHeapRegionClosure {
OopsInHeapRegionClosure* _blk;
G1CollectedHeap* _g1;
public:
IntoCSOopClosure(G1CollectedHeap* g1, OopsInHeapRegionClosure* blk) :
_g1(g1), _blk(blk) {}
void set_region(HeapRegion* from) {
_blk->set_region(from);
}
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) {
oop obj = oopDesc::load_decode_heap_oop(p);
if (_g1->obj_in_cs(obj)) _blk->do_oop(p);
}
bool apply_to_weak_ref_discovered_field() { return true; }
bool idempotent() { return true; }
};
class IntoCSRegionClosure: public HeapRegionClosure {
IntoCSOopClosure _blk;
G1CollectedHeap* _g1;
public:
IntoCSRegionClosure(G1CollectedHeap* g1, OopsInHeapRegionClosure* blk) :
_g1(g1), _blk(g1, blk) {}
bool doHeapRegion(HeapRegion* r) {
if (!r->in_collection_set()) {
_blk.set_region(r);
if (r->isHumongous()) {
if (r->startsHumongous()) {
oop obj = oop(r->bottom());
obj->oop_iterate(&_blk);
}
} else {
r->oop_before_save_marks_iterate(&_blk);
}
}
return false;
}
};
void
StupidG1RemSet::oops_into_collection_set_do(OopsInHeapRegionClosure* oc,
int worker_i) {
IntoCSRegionClosure rc(_g1, oc);
_g1->heap_region_iterate(&rc);
}
class VerifyRSCleanCardOopClosure: public OopClosure {
G1CollectedHeap* _g1;
public:
VerifyRSCleanCardOopClosure(G1CollectedHeap* g1) : _g1(g1) {}
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) {
oop obj = oopDesc::load_decode_heap_oop(p);
HeapRegion* to = _g1->heap_region_containing(obj);
guarantee(to == NULL || !to->in_collection_set(),
"Missed a rem set member.");
}
};
HRInto_G1RemSet::HRInto_G1RemSet(G1CollectedHeap* g1, CardTableModRefBS* ct_bs)
: G1RemSet(g1), _ct_bs(ct_bs), _g1p(_g1->g1_policy()),
_cg1r(g1->concurrent_g1_refine()),
_traversal_in_progress(false),
_cset_rs_update_cl(NULL),
_cards_scanned(NULL), _total_cards_scanned(0)
{
_seq_task = new SubTasksDone(NumSeqTasks);
guarantee(n_workers() > 0, "There should be some workers");
_cset_rs_update_cl = NEW_C_HEAP_ARRAY(OopsInHeapRegionClosure*, n_workers());
for (uint i = 0; i < n_workers(); i++) {
_cset_rs_update_cl[i] = NULL;
}
}
HRInto_G1RemSet::~HRInto_G1RemSet() {
delete _seq_task;
for (uint i = 0; i < n_workers(); i++) {
assert(_cset_rs_update_cl[i] == NULL, "it should be");
}
FREE_C_HEAP_ARRAY(OopsInHeapRegionClosure*, _cset_rs_update_cl);
}
void CountNonCleanMemRegionClosure::do_MemRegion(MemRegion mr) {
if (_g1->is_in_g1_reserved(mr.start())) {
_n += (int) ((mr.byte_size() / CardTableModRefBS::card_size));
if (_start_first == NULL) _start_first = mr.start();
}
}
class ScanRSClosure : public HeapRegionClosure {
size_t _cards_done, _cards;
G1CollectedHeap* _g1h;
OopsInHeapRegionClosure* _oc;
G1BlockOffsetSharedArray* _bot_shared;
CardTableModRefBS *_ct_bs;
int _worker_i;
int _block_size;
bool _try_claimed;
public:
ScanRSClosure(OopsInHeapRegionClosure* oc, int worker_i) :
_oc(oc),
_cards(0),
_cards_done(0),
_worker_i(worker_i),
_try_claimed(false)
{
_g1h = G1CollectedHeap::heap();
_bot_shared = _g1h->bot_shared();
_ct_bs = (CardTableModRefBS*) (_g1h->barrier_set());
_block_size = MAX2<int>(G1RSetScanBlockSize, 1);
}
void set_try_claimed() { _try_claimed = true; }
void scanCard(size_t index, HeapRegion *r) {
_cards_done++;
DirtyCardToOopClosure* cl =
r->new_dcto_closure(_oc,
CardTableModRefBS::Precise,
HeapRegionDCTOC::IntoCSFilterKind);
// Set the "from" region in the closure.
_oc->set_region(r);
HeapWord* card_start = _bot_shared->address_for_index(index);
HeapWord* card_end = card_start + G1BlockOffsetSharedArray::N_words;
Space *sp = SharedHeap::heap()->space_containing(card_start);
MemRegion sm_region;
if (ParallelGCThreads > 0) {
// first find the used area
sm_region = sp->used_region_at_save_marks();
} else {
// The closure is not idempotent. We shouldn't look at objects
// allocated during the GC.
sm_region = sp->used_region_at_save_marks();
}
MemRegion mr = sm_region.intersection(MemRegion(card_start,card_end));
if (!mr.is_empty()) {
cl->do_MemRegion(mr);
}
}
void printCard(HeapRegion* card_region, size_t card_index,
HeapWord* card_start) {
gclog_or_tty->print_cr("T %d Region [" PTR_FORMAT ", " PTR_FORMAT ") "
"RS names card %p: "
"[" PTR_FORMAT ", " PTR_FORMAT ")",
_worker_i,
card_region->bottom(), card_region->end(),
card_index,
card_start, card_start + G1BlockOffsetSharedArray::N_words);
}
bool doHeapRegion(HeapRegion* r) {
assert(r->in_collection_set(), "should only be called on elements of CS.");
HeapRegionRemSet* hrrs = r->rem_set();
if (hrrs->iter_is_complete()) return false; // All done.
if (!_try_claimed && !hrrs->claim_iter()) return false;
_g1h->push_dirty_cards_region(r);
// If we didn't return above, then
// _try_claimed || r->claim_iter()
// is true: either we're supposed to work on claimed-but-not-complete
// regions, or we successfully claimed the region.
HeapRegionRemSetIterator* iter = _g1h->rem_set_iterator(_worker_i);
hrrs->init_iterator(iter);
size_t card_index;
// We claim cards in block so as to recude the contention. The block size is determined by
// the G1RSetScanBlockSize parameter.
size_t jump_to_card = hrrs->iter_claimed_next(_block_size);
for (size_t current_card = 0; iter->has_next(card_index); current_card++) {
if (current_card >= jump_to_card + _block_size) {
jump_to_card = hrrs->iter_claimed_next(_block_size);
}
if (current_card < jump_to_card) continue;
HeapWord* card_start = _g1h->bot_shared()->address_for_index(card_index);
#if 0
gclog_or_tty->print("Rem set iteration yielded card [" PTR_FORMAT ", " PTR_FORMAT ").\n",
card_start, card_start + CardTableModRefBS::card_size_in_words);
#endif
HeapRegion* card_region = _g1h->heap_region_containing(card_start);
assert(card_region != NULL, "Yielding cards not in the heap?");
_cards++;
if (!card_region->is_on_dirty_cards_region_list()) {
_g1h->push_dirty_cards_region(card_region);
}
// If the card is dirty, then we will scan it during updateRS.
if (!card_region->in_collection_set() && !_ct_bs->is_card_dirty(card_index)) {
// We make the card as "claimed" lazily (so races are possible but they're benign),
// which reduces the number of duplicate scans (the rsets of the regions in the cset
// can intersect).
if (!_ct_bs->is_card_claimed(card_index)) {
_ct_bs->set_card_claimed(card_index);
scanCard(card_index, card_region);
}
}
}
if (!_try_claimed) {
hrrs->set_iter_complete();
}
return false;
}
// Set all cards back to clean.
void cleanup() {_g1h->cleanUpCardTable();}
size_t cards_done() { return _cards_done;}
size_t cards_looked_up() { return _cards;}
};
// We want the parallel threads to start their scanning at
// different collection set regions to avoid contention.
// If we have:
// n collection set regions
// p threads
// Then thread t will start at region t * floor (n/p)
HeapRegion* HRInto_G1RemSet::calculateStartRegion(int worker_i) {
HeapRegion* result = _g1p->collection_set();
if (ParallelGCThreads > 0) {
size_t cs_size = _g1p->collection_set_size();
int n_workers = _g1->workers()->total_workers();
size_t cs_spans = cs_size / n_workers;
size_t ind = cs_spans * worker_i;
for (size_t i = 0; i < ind; i++)
result = result->next_in_collection_set();
}
return result;
}
void HRInto_G1RemSet::scanRS(OopsInHeapRegionClosure* oc, int worker_i) {
double rs_time_start = os::elapsedTime();
HeapRegion *startRegion = calculateStartRegion(worker_i);
ScanRSClosure scanRScl(oc, worker_i);
_g1->collection_set_iterate_from(startRegion, &scanRScl);
scanRScl.set_try_claimed();
_g1->collection_set_iterate_from(startRegion, &scanRScl);
double scan_rs_time_sec = os::elapsedTime() - rs_time_start;
assert( _cards_scanned != NULL, "invariant" );
_cards_scanned[worker_i] = scanRScl.cards_done();
_g1p->record_scan_rs_time(worker_i, scan_rs_time_sec * 1000.0);
}
// Closure used for updating RSets and recording references that
// point into the collection set. Only called during an
// evacuation pause.
class RefineRecordRefsIntoCSCardTableEntryClosure: public CardTableEntryClosure {
G1RemSet* _g1rs;
DirtyCardQueue* _into_cset_dcq;
public:
RefineRecordRefsIntoCSCardTableEntryClosure(G1CollectedHeap* g1h,
DirtyCardQueue* into_cset_dcq) :
_g1rs(g1h->g1_rem_set()), _into_cset_dcq(into_cset_dcq)
{}
bool do_card_ptr(jbyte* card_ptr, int worker_i) {
// The only time we care about recording cards that
// contain references that point into the collection set
// is during RSet updating within an evacuation pause.
// In this case worker_i should be the id of a GC worker thread.
assert(SafepointSynchronize::is_at_safepoint(), "not during an evacuation pause");
assert(worker_i < (int) DirtyCardQueueSet::num_par_ids(), "should be a GC worker");
if (_g1rs->concurrentRefineOneCard(card_ptr, worker_i, true)) {
// 'card_ptr' contains references that point into the collection
// set. We need to record the card in the DCQS
// (G1CollectedHeap::into_cset_dirty_card_queue_set())
// that's used for that purpose.
//
// Enqueue the card
_into_cset_dcq->enqueue(card_ptr);
}
return true;
}
};
void HRInto_G1RemSet::updateRS(DirtyCardQueue* into_cset_dcq, int worker_i) {
double start = os::elapsedTime();
// Apply the given closure to all remaining log entries.
RefineRecordRefsIntoCSCardTableEntryClosure into_cset_update_rs_cl(_g1, into_cset_dcq);
_g1->iterate_dirty_card_closure(&into_cset_update_rs_cl, into_cset_dcq, false, worker_i);
// Now there should be no dirty cards.
if (G1RSLogCheckCardTable) {
CountNonCleanMemRegionClosure cl(_g1);
_ct_bs->mod_card_iterate(&cl);
// XXX This isn't true any more: keeping cards of young regions
// marked dirty broke it. Need some reasonable fix.
guarantee(cl.n() == 0, "Card table should be clean.");
}
_g1p->record_update_rs_time(worker_i, (os::elapsedTime() - start) * 1000.0);
}
#ifndef PRODUCT
class PrintRSClosure : public HeapRegionClosure {
int _count;
public:
PrintRSClosure() : _count(0) {}
bool doHeapRegion(HeapRegion* r) {
HeapRegionRemSet* hrrs = r->rem_set();
_count += (int) hrrs->occupied();
if (hrrs->occupied() == 0) {
gclog_or_tty->print("Heap Region [" PTR_FORMAT ", " PTR_FORMAT ") "
"has no remset entries\n",
r->bottom(), r->end());
} else {
gclog_or_tty->print("Printing rem set for heap region [" PTR_FORMAT ", " PTR_FORMAT ")\n",
r->bottom(), r->end());
r->print();
hrrs->print();
gclog_or_tty->print("\nDone printing rem set\n");
}
return false;
}
int occupied() {return _count;}
};
#endif
class CountRSSizeClosure: public HeapRegionClosure {
size_t _n;
size_t _tot;
size_t _max;
HeapRegion* _max_r;
enum {
N = 20,
MIN = 6
};
int _histo[N];
public:
CountRSSizeClosure() : _n(0), _tot(0), _max(0), _max_r(NULL) {
for (int i = 0; i < N; i++) _histo[i] = 0;
}
bool doHeapRegion(HeapRegion* r) {
if (!r->continuesHumongous()) {
size_t occ = r->rem_set()->occupied();
_n++;
_tot += occ;
if (occ > _max) {
_max = occ;
_max_r = r;
}
// Fit it into a histo bin.
int s = 1 << MIN;
int i = 0;
while (occ > (size_t) s && i < (N-1)) {
s = s << 1;
i++;
}
_histo[i]++;
}
return false;
}
size_t n() { return _n; }
size_t tot() { return _tot; }
size_t mx() { return _max; }
HeapRegion* mxr() { return _max_r; }
void print_histo() {
int mx = N;
while (mx >= 0) {
if (_histo[mx-1] > 0) break;
mx--;
}
gclog_or_tty->print_cr("Number of regions with given RS sizes:");
gclog_or_tty->print_cr(" <= %8d %8d", 1 << MIN, _histo[0]);
for (int i = 1; i < mx-1; i++) {
gclog_or_tty->print_cr(" %8d - %8d %8d",
(1 << (MIN + i - 1)) + 1,
1 << (MIN + i),
_histo[i]);
}
gclog_or_tty->print_cr(" > %8d %8d", (1 << (MIN+mx-2))+1, _histo[mx-1]);
}
};
void HRInto_G1RemSet::cleanupHRRS() {
HeapRegionRemSet::cleanup();
}
void
HRInto_G1RemSet::oops_into_collection_set_do(OopsInHeapRegionClosure* oc,
int worker_i) {
#if CARD_REPEAT_HISTO
ct_freq_update_histo_and_reset();
#endif
if (worker_i == 0) {
_cg1r->clear_and_record_card_counts();
}
// Make this into a command-line flag...
if (G1RSCountHisto && (ParallelGCThreads == 0 || worker_i == 0)) {
CountRSSizeClosure count_cl;
_g1->heap_region_iterate(&count_cl);
gclog_or_tty->print_cr("Avg of %d RS counts is %f, max is %d, "
"max region is " PTR_FORMAT,
count_cl.n(), (float)count_cl.tot()/(float)count_cl.n(),
count_cl.mx(), count_cl.mxr());
count_cl.print_histo();
}
// We cache the value of 'oc' closure into the appropriate slot in the
// _cset_rs_update_cl for this worker
assert(worker_i < (int)n_workers(), "sanity");
_cset_rs_update_cl[worker_i] = oc;
// A DirtyCardQueue that is used to hold cards containing references
// that point into the collection set. This DCQ is associated with a
// special DirtyCardQueueSet (see g1CollectedHeap.hpp). Under normal
// circumstances (i.e. the pause successfully completes), these cards
// are just discarded (there's no need to update the RSets of regions
// that were in the collection set - after the pause these regions
// are wholly 'free' of live objects. In the event of an evacuation
// failure the cards/buffers in this queue set are:
// * passed to the DirtyCardQueueSet that is used to manage deferred
// RSet updates, or
// * scanned for references that point into the collection set
// and the RSet of the corresponding region in the collection set
// is updated immediately.
DirtyCardQueue into_cset_dcq(&_g1->into_cset_dirty_card_queue_set());
assert((ParallelGCThreads > 0) || worker_i == 0, "invariant");
// The two flags below were introduced temporarily to serialize
// the updating and scanning of remembered sets. There are some
// race conditions when these two operations are done in parallel
// and they are causing failures. When we resolve said race
// conditions, we'll revert back to parallel remembered set
// updating and scanning. See CRs 6677707 and 6677708.
if (G1UseParallelRSetUpdating || (worker_i == 0)) {
updateRS(&into_cset_dcq, worker_i);
} else {
_g1p->record_update_rs_processed_buffers(worker_i, 0.0);
_g1p->record_update_rs_time(worker_i, 0.0);
}
if (G1UseParallelRSetScanning || (worker_i == 0)) {
scanRS(oc, worker_i);
} else {
_g1p->record_scan_rs_time(worker_i, 0.0);
}
// We now clear the cached values of _cset_rs_update_cl for this worker
_cset_rs_update_cl[worker_i] = NULL;
}
void HRInto_G1RemSet::
prepare_for_oops_into_collection_set_do() {
#if G1_REM_SET_LOGGING
PrintRSClosure cl;
_g1->collection_set_iterate(&cl);
#endif
cleanupHRRS();
ConcurrentG1Refine* cg1r = _g1->concurrent_g1_refine();
_g1->set_refine_cte_cl_concurrency(false);
DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
dcqs.concatenate_logs();
assert(!_traversal_in_progress, "Invariant between iterations.");
set_traversal(true);
if (ParallelGCThreads > 0) {
_seq_task->set_n_threads((int)n_workers());
}
guarantee( _cards_scanned == NULL, "invariant" );
_cards_scanned = NEW_C_HEAP_ARRAY(size_t, n_workers());
for (uint i = 0; i < n_workers(); ++i) {
_cards_scanned[i] = 0;
}
_total_cards_scanned = 0;
}
class cleanUpIteratorsClosure : public HeapRegionClosure {
bool doHeapRegion(HeapRegion *r) {
HeapRegionRemSet* hrrs = r->rem_set();
hrrs->init_for_par_iteration();
return false;
}
};
// This closure, applied to a DirtyCardQueueSet, is used to immediately
// update the RSets for the regions in the CSet. For each card it iterates
// through the oops which coincide with that card. It scans the reference
// fields in each oop; when it finds an oop that points into the collection
// set, the RSet for the region containing the referenced object is updated.
// Note: _par_traversal_in_progress in the G1RemSet must be FALSE; otherwise
// the UpdateRSetImmediate closure will cause cards to be enqueued on to
// the DCQS that we're iterating over, causing an infinite loop.
class UpdateRSetCardTableEntryIntoCSetClosure: public CardTableEntryClosure {
G1CollectedHeap* _g1;
CardTableModRefBS* _ct_bs;
public:
UpdateRSetCardTableEntryIntoCSetClosure(G1CollectedHeap* g1,
CardTableModRefBS* bs):
_g1(g1), _ct_bs(bs)
{ }
bool do_card_ptr(jbyte* card_ptr, int worker_i) {
// Construct the region representing the card.
HeapWord* start = _ct_bs->addr_for(card_ptr);
// And find the region containing it.
HeapRegion* r = _g1->heap_region_containing(start);
assert(r != NULL, "unexpected null");
// Scan oops in the card looking for references into the collection set
HeapWord* end = _ct_bs->addr_for(card_ptr + 1);
MemRegion scanRegion(start, end);
UpdateRSetImmediate update_rs_cl(_g1->g1_rem_set());
FilterIntoCSClosure update_rs_cset_oop_cl(NULL, _g1, &update_rs_cl);
FilterOutOfRegionClosure filter_then_update_rs_cset_oop_cl(r, &update_rs_cset_oop_cl);
// We can pass false as the "filter_young" parameter here as:
// * we should be in a STW pause,
// * the DCQS to which this closure is applied is used to hold
// references that point into the collection set from the prior
// RSet updating,
// * the post-write barrier shouldn't be logging updates to young
// regions (but there is a situation where this can happen - see
// the comment in HRInto_G1RemSet::concurrentRefineOneCard below -
// that should not be applicable here), and
// * during actual RSet updating, the filtering of cards in young
// regions in HeapRegion::oops_on_card_seq_iterate_careful is
// employed.
// As a result, when this closure is applied to "refs into cset"
// DCQS, we shouldn't see any cards in young regions.
update_rs_cl.set_region(r);
HeapWord* stop_point =
r->oops_on_card_seq_iterate_careful(scanRegion,
&filter_then_update_rs_cset_oop_cl,
false /* filter_young */);
// Since this is performed in the event of an evacuation failure, we
// we shouldn't see a non-null stop point
assert(stop_point == NULL, "saw an unallocated region");
return true;
}
};
void HRInto_G1RemSet::cleanup_after_oops_into_collection_set_do() {
guarantee( _cards_scanned != NULL, "invariant" );
_total_cards_scanned = 0;
for (uint i = 0; i < n_workers(); ++i)
_total_cards_scanned += _cards_scanned[i];
FREE_C_HEAP_ARRAY(size_t, _cards_scanned);
_cards_scanned = NULL;
// Cleanup after copy
#if G1_REM_SET_LOGGING
PrintRSClosure cl;
_g1->heap_region_iterate(&cl);
#endif
_g1->set_refine_cte_cl_concurrency(true);
cleanUpIteratorsClosure iterClosure;
_g1->collection_set_iterate(&iterClosure);
// Set all cards back to clean.
_g1->cleanUpCardTable();
set_traversal(false);
DirtyCardQueueSet& into_cset_dcqs = _g1->into_cset_dirty_card_queue_set();
int into_cset_n_buffers = into_cset_dcqs.completed_buffers_num();
if (_g1->evacuation_failed()) {
// Restore remembered sets for the regions pointing into the collection set.
if (G1DeferredRSUpdate) {
// If deferred RS updates are enabled then we just need to transfer
// the completed buffers from (a) the DirtyCardQueueSet used to hold
// cards that contain references that point into the collection set
// to (b) the DCQS used to hold the deferred RS updates
_g1->dirty_card_queue_set().merge_bufferlists(&into_cset_dcqs);
} else {
CardTableModRefBS* bs = (CardTableModRefBS*)_g1->barrier_set();
UpdateRSetCardTableEntryIntoCSetClosure update_rs_cset_immediate(_g1, bs);
int n_completed_buffers = 0;
while (into_cset_dcqs.apply_closure_to_completed_buffer(&update_rs_cset_immediate,
0, 0, true)) {
n_completed_buffers++;
}
assert(n_completed_buffers == into_cset_n_buffers, "missed some buffers");
}
}
// Free any completed buffers in the DirtyCardQueueSet used to hold cards
// which contain references that point into the collection.
_g1->into_cset_dirty_card_queue_set().clear();
assert(_g1->into_cset_dirty_card_queue_set().completed_buffers_num() == 0,
"all buffers should be freed");
_g1->into_cset_dirty_card_queue_set().clear_n_completed_buffers();
assert(!_traversal_in_progress, "Invariant between iterations.");
}
class UpdateRSObjectClosure: public ObjectClosure {
UpdateRSOopClosure* _update_rs_oop_cl;
public:
UpdateRSObjectClosure(UpdateRSOopClosure* update_rs_oop_cl) :
_update_rs_oop_cl(update_rs_oop_cl) {}
void do_object(oop obj) {
obj->oop_iterate(_update_rs_oop_cl);
}
};
class ScrubRSClosure: public HeapRegionClosure {
G1CollectedHeap* _g1h;
BitMap* _region_bm;
BitMap* _card_bm;
CardTableModRefBS* _ctbs;
public:
ScrubRSClosure(BitMap* region_bm, BitMap* card_bm) :
_g1h(G1CollectedHeap::heap()),
_region_bm(region_bm), _card_bm(card_bm),
_ctbs(NULL)
{
ModRefBarrierSet* bs = _g1h->mr_bs();
guarantee(bs->is_a(BarrierSet::CardTableModRef), "Precondition");
_ctbs = (CardTableModRefBS*)bs;
}
bool doHeapRegion(HeapRegion* r) {
if (!r->continuesHumongous()) {
r->rem_set()->scrub(_ctbs, _region_bm, _card_bm);
}
return false;
}
};
void HRInto_G1RemSet::scrub(BitMap* region_bm, BitMap* card_bm) {
ScrubRSClosure scrub_cl(region_bm, card_bm);
_g1->heap_region_iterate(&scrub_cl);
}
void HRInto_G1RemSet::scrub_par(BitMap* region_bm, BitMap* card_bm,
int worker_num, int claim_val) {
ScrubRSClosure scrub_cl(region_bm, card_bm);
_g1->heap_region_par_iterate_chunked(&scrub_cl, worker_num, claim_val);
}
static IntHistogram out_of_histo(50, 50);
class TriggerClosure : public OopClosure {
bool _trigger;
public:
TriggerClosure() : _trigger(false) { }
bool value() const { return _trigger; }
template <class T> void do_oop_nv(T* p) { _trigger = true; }
virtual void do_oop(oop* p) { do_oop_nv(p); }
virtual void do_oop(narrowOop* p) { do_oop_nv(p); }
};
class InvokeIfNotTriggeredClosure: public OopClosure {
TriggerClosure* _t;
OopClosure* _oc;
public:
InvokeIfNotTriggeredClosure(TriggerClosure* t, OopClosure* oc):
_t(t), _oc(oc) { }
template <class T> void do_oop_nv(T* p) {
if (!_t->value()) _oc->do_oop(p);
}
virtual void do_oop(oop* p) { do_oop_nv(p); }
virtual void do_oop(narrowOop* p) { do_oop_nv(p); }
};
class Mux2Closure : public OopClosure {
OopClosure* _c1;
OopClosure* _c2;
public:
Mux2Closure(OopClosure *c1, OopClosure *c2) : _c1(c1), _c2(c2) { }
template <class T> void do_oop_nv(T* p) {
_c1->do_oop(p); _c2->do_oop(p);
}
virtual void do_oop(oop* p) { do_oop_nv(p); }
virtual void do_oop(narrowOop* p) { do_oop_nv(p); }
};
bool HRInto_G1RemSet::concurrentRefineOneCard_impl(jbyte* card_ptr, int worker_i,
bool check_for_refs_into_cset) {
// Construct the region representing the card.
HeapWord* start = _ct_bs->addr_for(card_ptr);
// And find the region containing it.
HeapRegion* r = _g1->heap_region_containing(start);
assert(r != NULL, "unexpected null");
HeapWord* end = _ct_bs->addr_for(card_ptr + 1);
MemRegion dirtyRegion(start, end);
#if CARD_REPEAT_HISTO
init_ct_freq_table(_g1->g1_reserved_obj_bytes());
ct_freq_note_card(_ct_bs->index_for(start));
#endif
UpdateRSOopClosure update_rs_oop_cl(this, worker_i);
update_rs_oop_cl.set_from(r);
TriggerClosure trigger_cl;
FilterIntoCSClosure into_cs_cl(NULL, _g1, &trigger_cl);
InvokeIfNotTriggeredClosure invoke_cl(&trigger_cl, &into_cs_cl);
Mux2Closure mux(&invoke_cl, &update_rs_oop_cl);
FilterOutOfRegionClosure filter_then_update_rs_oop_cl(r,
(check_for_refs_into_cset ?
(OopClosure*)&mux :
(OopClosure*)&update_rs_oop_cl));
// Undirty the card.
*card_ptr = CardTableModRefBS::clean_card_val();
// We must complete this write before we do any of the reads below.
OrderAccess::storeload();
// And process it, being careful of unallocated portions of TLAB's.
// The region for the current card may be a young region. The
// current card may have been a card that was evicted from the
// card cache. When the card was inserted into the cache, we had
// determined that its region was non-young. While in the cache,
// the region may have been freed during a cleanup pause, reallocated
// and tagged as young.
//
// We wish to filter out cards for such a region but the current
// thread, if we're running conucrrently, may "see" the young type
// change at any time (so an earlier "is_young" check may pass or
// fail arbitrarily). We tell the iteration code to perform this
// filtering when it has been determined that there has been an actual
// allocation in this region and making it safe to check the young type.
bool filter_young = true;
HeapWord* stop_point =
r->oops_on_card_seq_iterate_careful(dirtyRegion,
&filter_then_update_rs_oop_cl,
filter_young);
// If stop_point is non-null, then we encountered an unallocated region
// (perhaps the unfilled portion of a TLAB.) For now, we'll dirty the
// card and re-enqueue: if we put off the card until a GC pause, then the
// unallocated portion will be filled in. Alternatively, we might try
// the full complexity of the technique used in "regular" precleaning.
if (stop_point != NULL) {
// The card might have gotten re-dirtied and re-enqueued while we
// worked. (In fact, it's pretty likely.)
if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
*card_ptr = CardTableModRefBS::dirty_card_val();
MutexLockerEx x(Shared_DirtyCardQ_lock,
Mutex::_no_safepoint_check_flag);
DirtyCardQueue* sdcq =
JavaThread::dirty_card_queue_set().shared_dirty_card_queue();
sdcq->enqueue(card_ptr);
}
} else {
out_of_histo.add_entry(filter_then_update_rs_oop_cl.out_of_region());
_conc_refine_cards++;
}
return trigger_cl.value();
}
bool HRInto_G1RemSet::concurrentRefineOneCard(jbyte* card_ptr, int worker_i,
bool check_for_refs_into_cset) {
// If the card is no longer dirty, nothing to do.
if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
// No need to return that this card contains refs that point
// into the collection set.
return false;
}
// Construct the region representing the card.
HeapWord* start = _ct_bs->addr_for(card_ptr);
// And find the region containing it.
HeapRegion* r = _g1->heap_region_containing(start);
if (r == NULL) {
guarantee(_g1->is_in_permanent(start), "Or else where?");
// Again no need to return that this card contains refs that
// point into the collection set.
return false; // Not in the G1 heap (might be in perm, for example.)
}
// Why do we have to check here whether a card is on a young region,
// given that we dirty young regions and, as a result, the
// post-barrier is supposed to filter them out and never to enqueue
// them? When we allocate a new region as the "allocation region" we
// actually dirty its cards after we release the lock, since card
// dirtying while holding the lock was a performance bottleneck. So,
// as a result, it is possible for other threads to actually
// allocate objects in the region (after the acquire the lock)
// before all the cards on the region are dirtied. This is unlikely,
// and it doesn't happen often, but it can happen. So, the extra
// check below filters out those cards.
if (r->is_young()) {
return false;
}
// While we are processing RSet buffers during the collection, we
// actually don't want to scan any cards on the collection set,
// since we don't want to update remebered sets with entries that
// point into the collection set, given that live objects from the
// collection set are about to move and such entries will be stale
// very soon. This change also deals with a reliability issue which
// involves scanning a card in the collection set and coming across
// an array that was being chunked and looking malformed. Note,
// however, that if evacuation fails, we have to scan any objects
// that were not moved and create any missing entries.
if (r->in_collection_set()) {
return false;
}
// Should we defer processing the card?
//
// Previously the result from the insert_cache call would be
// either card_ptr (implying that card_ptr was currently "cold"),
// null (meaning we had inserted the card ptr into the "hot"
// cache, which had some headroom), or a "hot" card ptr
// extracted from the "hot" cache.
//
// Now that the _card_counts cache in the ConcurrentG1Refine
// instance is an evicting hash table, the result we get back
// could be from evicting the card ptr in an already occupied
// bucket (in which case we have replaced the card ptr in the
// bucket with card_ptr and "defer" is set to false). To avoid
// having a data structure (updates to which would need a lock)
// to hold these unprocessed dirty cards, we need to immediately
// process card_ptr. The actions needed to be taken on return
// from cache_insert are summarized in the following table:
//
// res defer action
// --------------------------------------------------------------
// null false card evicted from _card_counts & replaced with
// card_ptr; evicted ptr added to hot cache.
// No need to process res; immediately process card_ptr
//
// null true card not evicted from _card_counts; card_ptr added
// to hot cache.
// Nothing to do.
//
// non-null false card evicted from _card_counts & replaced with
// card_ptr; evicted ptr is currently "cold" or
// caused an eviction from the hot cache.
// Immediately process res; process card_ptr.
//
// non-null true card not evicted from _card_counts; card_ptr is
// currently cold, or caused an eviction from hot
// cache.
// Immediately process res; no need to process card_ptr.
jbyte* res = card_ptr;
bool defer = false;
// This gets set to true if the card being refined has references
// that point into the collection set.
bool oops_into_cset = false;
if (_cg1r->use_cache()) {
jbyte* res = _cg1r->cache_insert(card_ptr, &defer);
if (res != NULL && (res != card_ptr || defer)) {
start = _ct_bs->addr_for(res);
r = _g1->heap_region_containing(start);
if (r == NULL) {
assert(_g1->is_in_permanent(start), "Or else where?");
} else {
// Checking whether the region we got back from the cache
// is young here is inappropriate. The region could have been
// freed, reallocated and tagged as young while in the cache.
// Hence we could see its young type change at any time.
//
// Process card pointer we get back from the hot card cache. This
// will check whether the region containing the card is young
// _after_ checking that the region has been allocated from.
oops_into_cset = concurrentRefineOneCard_impl(res, worker_i,
false /* check_for_refs_into_cset */);
// The above call to concurrentRefineOneCard_impl is only
// performed if the hot card cache is enabled. This cache is
// disabled during an evacuation pause - which is the only
// time when we need know if the card contains references
// that point into the collection set. Also when the hot card
// cache is enabled, this code is executed by the concurrent
// refine threads - rather than the GC worker threads - and
// concurrentRefineOneCard_impl will return false.
assert(!oops_into_cset, "should not see true here");
}
}
}
if (!defer) {
oops_into_cset =
concurrentRefineOneCard_impl(card_ptr, worker_i, check_for_refs_into_cset);
// We should only be detecting that the card contains references
// that point into the collection set if the current thread is
// a GC worker thread.
assert(!oops_into_cset || SafepointSynchronize::is_at_safepoint(),
"invalid result at non safepoint");
}
return oops_into_cset;
}
class HRRSStatsIter: public HeapRegionClosure {
size_t _occupied;
size_t _total_mem_sz;
size_t _max_mem_sz;
HeapRegion* _max_mem_sz_region;
public:
HRRSStatsIter() :
_occupied(0),
_total_mem_sz(0),
_max_mem_sz(0),
_max_mem_sz_region(NULL)
{}
bool doHeapRegion(HeapRegion* r) {
if (r->continuesHumongous()) return false;
size_t mem_sz = r->rem_set()->mem_size();
if (mem_sz > _max_mem_sz) {
_max_mem_sz = mem_sz;
_max_mem_sz_region = r;
}
_total_mem_sz += mem_sz;
size_t occ = r->rem_set()->occupied();
_occupied += occ;
return false;
}
size_t total_mem_sz() { return _total_mem_sz; }
size_t max_mem_sz() { return _max_mem_sz; }
size_t occupied() { return _occupied; }
HeapRegion* max_mem_sz_region() { return _max_mem_sz_region; }
};
class PrintRSThreadVTimeClosure : public ThreadClosure {
public:
virtual void do_thread(Thread *t) {
ConcurrentG1RefineThread* crt = (ConcurrentG1RefineThread*) t;
gclog_or_tty->print(" %5.2f", crt->vtime_accum());
}
};
void HRInto_G1RemSet::print_summary_info() {
G1CollectedHeap* g1 = G1CollectedHeap::heap();
#if CARD_REPEAT_HISTO
gclog_or_tty->print_cr("\nG1 card_repeat count histogram: ");
gclog_or_tty->print_cr(" # of repeats --> # of cards with that number.");
card_repeat_count.print_on(gclog_or_tty);
#endif
if (FILTEROUTOFREGIONCLOSURE_DOHISTOGRAMCOUNT) {
gclog_or_tty->print_cr("\nG1 rem-set out-of-region histogram: ");
gclog_or_tty->print_cr(" # of CS ptrs --> # of cards with that number.");
out_of_histo.print_on(gclog_or_tty);
}
gclog_or_tty->print_cr("\n Concurrent RS processed %d cards",
_conc_refine_cards);
DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
jint tot_processed_buffers =
dcqs.processed_buffers_mut() + dcqs.processed_buffers_rs_thread();
gclog_or_tty->print_cr(" Of %d completed buffers:", tot_processed_buffers);
gclog_or_tty->print_cr(" %8d (%5.1f%%) by conc RS threads.",
dcqs.processed_buffers_rs_thread(),
100.0*(float)dcqs.processed_buffers_rs_thread()/
(float)tot_processed_buffers);
gclog_or_tty->print_cr(" %8d (%5.1f%%) by mutator threads.",
dcqs.processed_buffers_mut(),
100.0*(float)dcqs.processed_buffers_mut()/
(float)tot_processed_buffers);
gclog_or_tty->print_cr(" Conc RS threads times(s)");
PrintRSThreadVTimeClosure p;
gclog_or_tty->print(" ");
g1->concurrent_g1_refine()->threads_do(&p);
gclog_or_tty->print_cr("");
if (G1UseHRIntoRS) {
HRRSStatsIter blk;
g1->heap_region_iterate(&blk);
gclog_or_tty->print_cr(" Total heap region rem set sizes = " SIZE_FORMAT "K."
" Max = " SIZE_FORMAT "K.",
blk.total_mem_sz()/K, blk.max_mem_sz()/K);
gclog_or_tty->print_cr(" Static structures = " SIZE_FORMAT "K,"
" free_lists = " SIZE_FORMAT "K.",
HeapRegionRemSet::static_mem_size()/K,
HeapRegionRemSet::fl_mem_size()/K);
gclog_or_tty->print_cr(" %d occupied cards represented.",
blk.occupied());
gclog_or_tty->print_cr(" Max sz region = [" PTR_FORMAT ", " PTR_FORMAT " )"
", cap = " SIZE_FORMAT "K, occ = " SIZE_FORMAT "K.",
blk.max_mem_sz_region()->bottom(), blk.max_mem_sz_region()->end(),
(blk.max_mem_sz_region()->rem_set()->mem_size() + K - 1)/K,
(blk.max_mem_sz_region()->rem_set()->occupied() + K - 1)/K);
gclog_or_tty->print_cr(" Did %d coarsenings.",
HeapRegionRemSet::n_coarsenings());
}
}
void HRInto_G1RemSet::prepare_for_verify() {
if (G1HRRSFlushLogBuffersOnVerify &&
(VerifyBeforeGC || VerifyAfterGC)
&& !_g1->full_collection()) {
cleanupHRRS();
_g1->set_refine_cte_cl_concurrency(false);
if (SafepointSynchronize::is_at_safepoint()) {
DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
dcqs.concatenate_logs();
}
bool cg1r_use_cache = _cg1r->use_cache();
_cg1r->set_use_cache(false);
DirtyCardQueue into_cset_dcq(&_g1->into_cset_dirty_card_queue_set());
updateRS(&into_cset_dcq, 0);
_g1->into_cset_dirty_card_queue_set().clear();
_cg1r->set_use_cache(cg1r_use_cache);
assert(JavaThread::dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
}
}