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8038423: G1: Decommit memory within heap

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Allow G1 to decommit memory of arbitrary regions within the heap and their associated auxiliary data structures card table, BOT, hot card cache, and mark bitmaps.

Reviewed-by: mgerdin, brutisso, jwilhelm
This commit is contained in:
Thomas Schatzl 2014-08-19 14:09:10 +02:00
parent 2617d54723
commit 100e51a339
32 changed files with 1322 additions and 579 deletions
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249
hotspot/src/share/vm/gc_implementation/g1/concurrentMark.cpp
View file

@ -36,6 +36,7 @@
#include "gc_implementation/g1/heapRegion.inline.hpp"
#include "gc_implementation/g1/heapRegionRemSet.hpp"
#include "gc_implementation/g1/heapRegionSeq.inline.hpp"
#include "gc_implementation/g1/heapRegionSet.inline.hpp"
#include "gc_implementation/shared/vmGCOperations.hpp"
#include "gc_implementation/shared/gcTimer.hpp"
#include "gc_implementation/shared/gcTrace.hpp"
@ -99,12 +100,12 @@ int CMBitMapRO::heapWordDiffToOffsetDiff(size_t diff) const {
}
#ifndef PRODUCT
bool CMBitMapRO::covers(ReservedSpace heap_rs) const {
bool CMBitMapRO::covers(MemRegion heap_rs) const {
// assert(_bm.map() == _virtual_space.low(), "map inconsistency");
assert(((size_t)_bm.size() * ((size_t)1 << _shifter)) == _bmWordSize,
"size inconsistency");
return _bmStartWord == (HeapWord*)(heap_rs.base()) &&
_bmWordSize == heap_rs.size()>>LogHeapWordSize;
return _bmStartWord == (HeapWord*)(heap_rs.start()) &&
_bmWordSize == heap_rs.word_size();
}
#endif
@ -112,33 +113,73 @@ void CMBitMapRO::print_on_error(outputStream* st, const char* prefix) const {
_bm.print_on_error(st, prefix);
}
bool CMBitMap::allocate(ReservedSpace heap_rs) {
_bmStartWord = (HeapWord*)(heap_rs.base());
_bmWordSize = heap_rs.size()/HeapWordSize; // heap_rs.size() is in bytes
ReservedSpace brs(ReservedSpace::allocation_align_size_up(
(_bmWordSize >> (_shifter + LogBitsPerByte)) + 1));
if (!brs.is_reserved()) {
warning("ConcurrentMark marking bit map allocation failure");
return false;
}
MemTracker::record_virtual_memory_type((address)brs.base(), mtGC);
// For now we'll just commit all of the bit map up front.
// Later on we'll try to be more parsimonious with swap.
if (!_virtual_space.initialize(brs, brs.size())) {
warning("ConcurrentMark marking bit map backing store failure");
return false;
}
assert(_virtual_space.committed_size() == brs.size(),
"didn't reserve backing store for all of concurrent marking bit map?");
_bm.set_map((BitMap::bm_word_t*)_virtual_space.low());
assert(_virtual_space.committed_size() << (_shifter + LogBitsPerByte) >=
_bmWordSize, "inconsistency in bit map sizing");
_bm.set_size(_bmWordSize >> _shifter);
return true;
size_t CMBitMap::compute_size(size_t heap_size) {
return heap_size / mark_distance();
}
size_t CMBitMap::mark_distance() {
return MinObjAlignmentInBytes * BitsPerByte;
}
void CMBitMap::initialize(MemRegion heap, G1RegionToSpaceMapper* storage) {
_bmStartWord = heap.start();
_bmWordSize = heap.word_size();
_bm.set_map((BitMap::bm_word_t*) storage->reserved().start());
_bm.set_size(_bmWordSize >> _shifter);
storage->set_mapping_changed_listener(&_listener);
}
void CMBitMapMappingChangedListener::on_commit(uint start_region, size_t num_regions) {
// We need to clear the bitmap on commit, removing any existing information.
MemRegion mr(G1CollectedHeap::heap()->bottom_addr_for_region(start_region), num_regions * HeapRegion::GrainWords);
_bm->clearRange(mr);
}
// Closure used for clearing the given mark bitmap.
class ClearBitmapHRClosure : public HeapRegionClosure {
private:
ConcurrentMark* _cm;
CMBitMap* _bitmap;
bool _may_yield; // The closure may yield during iteration. If yielded, abort the iteration.
public:
ClearBitmapHRClosure(ConcurrentMark* cm, CMBitMap* bitmap, bool may_yield) : HeapRegionClosure(), _cm(cm), _bitmap(bitmap), _may_yield(may_yield) {
assert(!may_yield || cm != NULL, "CM must be non-NULL if this closure is expected to yield.");
}
virtual bool doHeapRegion(HeapRegion* r) {
size_t const chunk_size_in_words = M / HeapWordSize;
HeapWord* cur = r->bottom();
HeapWord* const end = r->end();
while (cur < end) {
MemRegion mr(cur, MIN2(cur + chunk_size_in_words, end));
_bitmap->clearRange(mr);
cur += chunk_size_in_words;
// Abort iteration if after yielding the marking has been aborted.
if (_may_yield && _cm->do_yield_check() && _cm->has_aborted()) {
return true;
}
// Repeat the asserts from before the start of the closure. We will do them
// as asserts here to minimize their overhead on the product. However, we
// will have them as guarantees at the beginning / end of the bitmap
// clearing to get some checking in the product.
assert(!_may_yield || _cm->cmThread()->during_cycle(), "invariant");
assert(!_may_yield || !G1CollectedHeap::heap()->mark_in_progress(), "invariant");
}
return false;
}
};
void CMBitMap::clearAll() {
_bm.clear();
ClearBitmapHRClosure cl(NULL, this, false /* may_yield */);
G1CollectedHeap::heap()->heap_region_iterate(&cl);
guarantee(cl.complete(), "Must have completed iteration.");
return;
}
@ -483,10 +524,10 @@ uint ConcurrentMark::scale_parallel_threads(uint n_par_threads) {
return MAX2((n_par_threads + 2) / 4, 1U);
}
ConcurrentMark::ConcurrentMark(G1CollectedHeap* g1h, ReservedSpace heap_rs) :
ConcurrentMark::ConcurrentMark(G1CollectedHeap* g1h, G1RegionToSpaceMapper* prev_bitmap_storage, G1RegionToSpaceMapper* next_bitmap_storage) :
_g1h(g1h),
_markBitMap1(log2_intptr(MinObjAlignment)),
_markBitMap2(log2_intptr(MinObjAlignment)),
_markBitMap1(),
_markBitMap2(),
_parallel_marking_threads(0),
_max_parallel_marking_threads(0),
_sleep_factor(0.0),
@ -495,7 +536,7 @@ ConcurrentMark::ConcurrentMark(G1CollectedHeap* g1h, ReservedSpace heap_rs) :
_cleanup_task_overhead(1.0),
_cleanup_list("Cleanup List"),
_region_bm((BitMap::idx_t)(g1h->max_regions()), false /* in_resource_area*/),
_card_bm((heap_rs.size() + CardTableModRefBS::card_size - 1) >>
_card_bm((g1h->reserved_region().byte_size() + CardTableModRefBS::card_size - 1) >>
CardTableModRefBS::card_shift,
false /* in_resource_area*/),
@ -545,14 +586,8 @@ ConcurrentMark::ConcurrentMark(G1CollectedHeap* g1h, ReservedSpace heap_rs) :
"heap end = " PTR_FORMAT, p2i(_heap_start), p2i(_heap_end));
}
if (!_markBitMap1.allocate(heap_rs)) {
warning("Failed to allocate first CM bit map");
return;
}
if (!_markBitMap2.allocate(heap_rs)) {
warning("Failed to allocate second CM bit map");
return;
}
_markBitMap1.initialize(g1h->reserved_region(), prev_bitmap_storage);
_markBitMap2.initialize(g1h->reserved_region(), next_bitmap_storage);
// Create & start a ConcurrentMark thread.
_cmThread = new ConcurrentMarkThread(this);
@ -563,8 +598,8 @@ ConcurrentMark::ConcurrentMark(G1CollectedHeap* g1h, ReservedSpace heap_rs) :
}
assert(CGC_lock != NULL, "Where's the CGC_lock?");
assert(_markBitMap1.covers(heap_rs), "_markBitMap1 inconsistency");
assert(_markBitMap2.covers(heap_rs), "_markBitMap2 inconsistency");
assert(_markBitMap1.covers(g1h->reserved_region()), "_markBitMap1 inconsistency");
assert(_markBitMap2.covers(g1h->reserved_region()), "_markBitMap2 inconsistency");
SATBMarkQueueSet& satb_qs = JavaThread::satb_mark_queue_set();
satb_qs.set_buffer_size(G1SATBBufferSize);
@ -724,37 +759,17 @@ ConcurrentMark::ConcurrentMark(G1CollectedHeap* g1h, ReservedSpace heap_rs) :
clear_all_count_data();
// so that the call below can read a sensible value
_heap_start = (HeapWord*) heap_rs.base();
_heap_start = g1h->reserved_region().start();
set_non_marking_state();
_completed_initialization = true;
}
void ConcurrentMark::update_heap_boundaries(MemRegion bounds, bool force) {
// If concurrent marking is not in progress, then we do not need to
// update _heap_end.
if (!concurrent_marking_in_progress() && !force) return;
assert(bounds.start() == _heap_start, "start shouldn't change");
HeapWord* new_end = bounds.end();
if (new_end > _heap_end) {
// The heap has been expanded.
_heap_end = new_end;
}
// Notice that the heap can also shrink. However, this only happens
// during a Full GC (at least currently) and the entire marking
// phase will bail out and the task will not be restarted. So, let's
// do nothing.
}
void ConcurrentMark::reset() {
// Starting values for these two. This should be called in a STW
// phase. CM will be notified of any future g1_committed expansions
// will be at the end of evacuation pauses, when tasks are
// inactive.
MemRegion committed = _g1h->g1_committed();
_heap_start = committed.start();
_heap_end = committed.end();
// phase.
MemRegion reserved = _g1h->g1_reserved();
_heap_start = reserved.start();
_heap_end = reserved.end();
// Separated the asserts so that we know which one fires.
assert(_heap_start != NULL, "heap bounds should look ok");
@ -826,7 +841,6 @@ void ConcurrentMark::set_concurrency_and_phase(uint active_tasks, bool concurren
assert(out_of_regions(),
err_msg("only way to get here: _finger: "PTR_FORMAT", _heap_end: "PTR_FORMAT,
p2i(_finger), p2i(_heap_end)));
update_heap_boundaries(_g1h->g1_committed(), true);
}
}
@ -845,7 +859,6 @@ ConcurrentMark::~ConcurrentMark() {
void ConcurrentMark::clearNextBitmap() {
G1CollectedHeap* g1h = G1CollectedHeap::heap();
G1CollectorPolicy* g1p = g1h->g1_policy();
// Make sure that the concurrent mark thread looks to still be in
// the current cycle.
@ -857,41 +870,36 @@ void ConcurrentMark::clearNextBitmap() {
// is the case.
guarantee(!g1h->mark_in_progress(), "invariant");
// clear the mark bitmap (no grey objects to start with).
// We need to do this in chunks and offer to yield in between
// each chunk.
HeapWord* start = _nextMarkBitMap->startWord();
HeapWord* end = _nextMarkBitMap->endWord();
HeapWord* cur = start;
size_t chunkSize = M;
while (cur < end) {
HeapWord* next = cur + chunkSize;
if (next > end) {
next = end;
}
MemRegion mr(cur,next);
_nextMarkBitMap->clearRange(mr);
cur = next;
do_yield_check();
ClearBitmapHRClosure cl(this, _nextMarkBitMap, true /* may_yield */);
g1h->heap_region_iterate(&cl);
// Repeat the asserts from above. We'll do them as asserts here to
// minimize their overhead on the product. However, we'll have
// them as guarantees at the beginning / end of the bitmap
// clearing to get some checking in the product.
assert(cmThread()->during_cycle(), "invariant");
assert(!g1h->mark_in_progress(), "invariant");
// Clear the liveness counting data. If the marking has been aborted, the abort()
// call already did that.
if (cl.complete()) {
clear_all_count_data();
}
// Clear the liveness counting data
clear_all_count_data();
// Repeat the asserts from above.
guarantee(cmThread()->during_cycle(), "invariant");
guarantee(!g1h->mark_in_progress(), "invariant");
}
class CheckBitmapClearHRClosure : public HeapRegionClosure {
CMBitMap* _bitmap;
bool _error;
public:
CheckBitmapClearHRClosure(CMBitMap* bitmap) : _bitmap(bitmap) {
}
virtual bool doHeapRegion(HeapRegion* r) {
return _bitmap->getNextMarkedWordAddress(r->bottom(), r->end()) != r->end();
}
};
bool ConcurrentMark::nextMarkBitmapIsClear() {
return _nextMarkBitMap->getNextMarkedWordAddress(_heap_start, _heap_end) == _heap_end;
CheckBitmapClearHRClosure cl(_nextMarkBitMap);
_g1h->heap_region_iterate(&cl);
return cl.complete();
}
class NoteStartOfMarkHRClosure: public HeapRegionClosure {
@ -2192,8 +2200,8 @@ void ConcurrentMark::completeCleanup() {
_cleanup_list.length());
}
// Noone else should be accessing the _cleanup_list at this point,
// so it's not necessary to take any locks
// No one else should be accessing the _cleanup_list at this point,
// so it is not necessary to take any locks
while (!_cleanup_list.is_empty()) {
HeapRegion* hr = _cleanup_list.remove_region(true /* from_head */);
assert(hr != NULL, "Got NULL from a non-empty list");
@ -2979,22 +2987,25 @@ ConcurrentMark::claim_region(uint worker_id) {
// claim_region() and a humongous object allocation might force us
// to do a bit of unnecessary work (due to some unnecessary bitmap
// iterations) but it should not introduce and correctness issues.
HeapRegion* curr_region = _g1h->heap_region_containing_raw(finger);
HeapWord* bottom = curr_region->bottom();
HeapWord* end = curr_region->end();
HeapWord* limit = curr_region->next_top_at_mark_start();
HeapRegion* curr_region = _g1h->heap_region_containing_raw(finger);
if (verbose_low()) {
gclog_or_tty->print_cr("[%u] curr_region = "PTR_FORMAT" "
"["PTR_FORMAT", "PTR_FORMAT"), "
"limit = "PTR_FORMAT,
worker_id, p2i(curr_region), p2i(bottom), p2i(end), p2i(limit));
}
// Above heap_region_containing_raw may return NULL as we always scan claim
// until the end of the heap. In this case, just jump to the next region.
HeapWord* end = curr_region != NULL ? curr_region->end() : finger + HeapRegion::GrainWords;
// Is the gap between reading the finger and doing the CAS too long?
HeapWord* res = (HeapWord*) Atomic::cmpxchg_ptr(end, &_finger, finger);
if (res == finger) {
if (res == finger && curr_region != NULL) {
// we succeeded
HeapWord* bottom = curr_region->bottom();
HeapWord* limit = curr_region->next_top_at_mark_start();
if (verbose_low()) {
gclog_or_tty->print_cr("[%u] curr_region = "PTR_FORMAT" "
"["PTR_FORMAT", "PTR_FORMAT"), "
"limit = "PTR_FORMAT,
worker_id, p2i(curr_region), p2i(bottom), p2i(end), p2i(limit));
}
// notice that _finger == end cannot be guaranteed here since,
// someone else might have moved the finger even further
@ -3025,10 +3036,17 @@ ConcurrentMark::claim_region(uint worker_id) {
} else {
assert(_finger > finger, "the finger should have moved forward");
if (verbose_low()) {
gclog_or_tty->print_cr("[%u] somebody else moved the finger, "
"global finger = "PTR_FORMAT", "
"our finger = "PTR_FORMAT,
worker_id, p2i(_finger), p2i(finger));
if (curr_region == NULL) {
gclog_or_tty->print_cr("[%u] found uncommitted region, moving finger, "
"global finger = "PTR_FORMAT", "
"our finger = "PTR_FORMAT,
worker_id, p2i(_finger), p2i(finger));
} else {
gclog_or_tty->print_cr("[%u] somebody else moved the finger, "
"global finger = "PTR_FORMAT", "
"our finger = "PTR_FORMAT,
worker_id, p2i(_finger), p2i(finger));
}
}
// read it again
@ -3143,8 +3161,10 @@ void ConcurrentMark::verify_no_cset_oops(bool verify_stacks,
// happens, heap_region_containing() will return the bottom of the
// corresponding starts humongous region and the check below will
// not hold any more.
// Since we always iterate over all regions, we might get a NULL HeapRegion
// here.
HeapRegion* global_hr = _g1h->heap_region_containing_raw(global_finger);
guarantee(global_finger == global_hr->bottom(),
guarantee(global_hr == NULL || global_finger == global_hr->bottom(),
err_msg("global finger: "PTR_FORMAT" region: "HR_FORMAT,
p2i(global_finger), HR_FORMAT_PARAMS(global_hr)));
}
@ -3157,7 +3177,7 @@ void ConcurrentMark::verify_no_cset_oops(bool verify_stacks,
if (task_finger != NULL && task_finger < _heap_end) {
// See above note on the global finger verification.
HeapRegion* task_hr = _g1h->heap_region_containing_raw(task_finger);
guarantee(task_finger == task_hr->bottom() ||
guarantee(task_hr == NULL || task_finger == task_hr->bottom() ||
!task_hr->in_collection_set(),
err_msg("task finger: "PTR_FORMAT" region: "HR_FORMAT,
p2i(task_finger), HR_FORMAT_PARAMS(task_hr)));
@ -4673,7 +4693,6 @@ G1PrintRegionLivenessInfoClosure(outputStream* out, const char* phase_name)
_hum_prev_live_bytes(0), _hum_next_live_bytes(0),
_total_remset_bytes(0), _total_strong_code_roots_bytes(0) {
G1CollectedHeap* g1h = G1CollectedHeap::heap();
MemRegion g1_committed = g1h->g1_committed();
MemRegion g1_reserved = g1h->g1_reserved();
double now = os::elapsedTime();
@ -4681,10 +4700,8 @@ G1PrintRegionLivenessInfoClosure(outputStream* out, const char* phase_name)
_out->cr();
_out->print_cr(G1PPRL_LINE_PREFIX" PHASE %s @ %1.3f", phase_name, now);
_out->print_cr(G1PPRL_LINE_PREFIX" HEAP"
G1PPRL_SUM_ADDR_FORMAT("committed")
G1PPRL_SUM_ADDR_FORMAT("reserved")
G1PPRL_SUM_BYTE_FORMAT("region-size"),
p2i(g1_committed.start()), p2i(g1_committed.end()),
p2i(g1_reserved.start()), p2i(g1_reserved.end()),
HeapRegion::GrainBytes);
_out->print_cr(G1PPRL_LINE_PREFIX);