< prev index next > src/hotspot/share/gc/shared/collectedHeap.cpp
RFE_8195103_reduce_initial_card_marks
/*
- * Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2018, 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.
_barrier_set(NULL),
_is_gc_active(false),
_total_collections(0),
_total_full_collections(0),
_gc_cause(GCCause::_no_gc),
- _gc_lastcause(GCCause::_no_gc),
- _defer_initial_card_mark(false) // strengthened by subclass in pre_initialize() below.
+ _gc_lastcause(GCCause::_no_gc)
{
const size_t max_len = size_t(arrayOopDesc::max_array_length(T_INT));
const size_t elements_per_word = HeapWordSize / sizeof(jint);
_filler_array_max_size = align_object_size(filler_array_hdr_size() +
max_len / elements_per_word);
void CollectedHeap::set_barrier_set(BarrierSet* barrier_set) {
_barrier_set = barrier_set;
BarrierSet::set_bs(barrier_set);
}
-void CollectedHeap::pre_initialize() {
- // Used for ReduceInitialCardMarks (when COMPILER2 is used);
- // otherwise remains unused.
-#if COMPILER2_OR_JVMCI
- _defer_initial_card_mark = is_server_compilation_mode_vm() && ReduceInitialCardMarks && can_elide_tlab_store_barriers()
- && (DeferInitialCardMark || card_mark_must_follow_store());
-#else
- assert(_defer_initial_card_mark == false, "Who would set it?");
-#endif
-}
-
#ifndef PRODUCT
void CollectedHeap::check_for_bad_heap_word_value(HeapWord* addr, size_t size) {
if (CheckMemoryInitialization && ZapUnusedHeapArea) {
for (size_t slot = 0; slot < size; slot += 1) {
assert((*(intptr_t*) (addr + slot)) != ((intptr_t) badHeapWordVal),
}
thread->tlab().fill(obj, obj + size, new_tlab_size);
return obj;
}
-void CollectedHeap::flush_deferred_store_barrier(JavaThread* thread) {
- MemRegion deferred = thread->deferred_card_mark();
- if (!deferred.is_empty()) {
- assert(_defer_initial_card_mark, "Otherwise should be empty");
- {
- // Verify that the storage points to a parsable object in heap
- DEBUG_ONLY(oop old_obj = oop(deferred.start());)
- assert(is_in(old_obj), "Not in allocated heap");
- assert(!can_elide_initializing_store_barrier(old_obj),
- "Else should have been filtered in new_store_pre_barrier()");
- assert(oopDesc::is_oop(old_obj, true), "Not an oop");
- assert(deferred.word_size() == (size_t)(old_obj->size()),
- "Mismatch: multiple objects?");
- }
- BarrierSet* bs = barrier_set();
- bs->write_region(deferred);
- // "Clear" the deferred_card_mark field
- thread->set_deferred_card_mark(MemRegion());
- }
- assert(thread->deferred_card_mark().is_empty(), "invariant");
-}
-
size_t CollectedHeap::max_tlab_size() const {
// TLABs can't be bigger than we can fill with a int[Integer.MAX_VALUE].
// This restriction could be removed by enabling filling with multiple arrays.
// If we compute that the reasonable way as
// header_size + ((sizeof(jint) * max_jint) / HeapWordSize)
sizeof(jint) *
((juint) max_jint / (size_t) HeapWordSize);
return align_down(max_int_size, MinObjAlignment);
}
-// Helper for ReduceInitialCardMarks. For performance,
-// compiled code may elide card-marks for initializing stores
-// to a newly allocated object along the fast-path. We
-// compensate for such elided card-marks as follows:
-// (a) Generational, non-concurrent collectors, such as
-// GenCollectedHeap(ParNew,DefNew,Tenured) and
-// ParallelScavengeHeap(ParallelGC, ParallelOldGC)
-// need the card-mark if and only if the region is
-// in the old gen, and do not care if the card-mark
-// succeeds or precedes the initializing stores themselves,
-// so long as the card-mark is completed before the next
-// scavenge. For all these cases, we can do a card mark
-// at the point at which we do a slow path allocation
-// in the old gen, i.e. in this call.
-// (b) GenCollectedHeap(ConcurrentMarkSweepGeneration) requires
-// in addition that the card-mark for an old gen allocated
-// object strictly follow any associated initializing stores.
-// In these cases, the memRegion remembered below is
-// used to card-mark the entire region either just before the next
-// slow-path allocation by this thread or just before the next scavenge or
-// CMS-associated safepoint, whichever of these events happens first.
-// (The implicit assumption is that the object has been fully
-// initialized by this point, a fact that we assert when doing the
-// card-mark.)
-// (c) G1CollectedHeap(G1) uses two kinds of write barriers. When a
-// G1 concurrent marking is in progress an SATB (pre-write-)barrier
-// is used to remember the pre-value of any store. Initializing
-// stores will not need this barrier, so we need not worry about
-// compensating for the missing pre-barrier here. Turning now
-// to the post-barrier, we note that G1 needs a RS update barrier
-// which simply enqueues a (sequence of) dirty cards which may
-// optionally be refined by the concurrent update threads. Note
-// that this barrier need only be applied to a non-young write,
-// but, like in CMS, because of the presence of concurrent refinement
-// (much like CMS' precleaning), must strictly follow the oop-store.
-// Thus, using the same protocol for maintaining the intended
-// invariants turns out, serendepitously, to be the same for both
-// G1 and CMS.
-//
-// For any future collector, this code should be reexamined with
-// that specific collector in mind, and the documentation above suitably
-// extended and updated.
-oop CollectedHeap::new_store_pre_barrier(JavaThread* thread, oop new_obj) {
- // If a previous card-mark was deferred, flush it now.
- flush_deferred_store_barrier(thread);
- if (can_elide_initializing_store_barrier(new_obj) ||
- new_obj->is_typeArray()) {
- // Arrays of non-references don't need a pre-barrier.
- // The deferred_card_mark region should be empty
- // following the flush above.
- assert(thread->deferred_card_mark().is_empty(), "Error");
- } else {
- MemRegion mr((HeapWord*)new_obj, new_obj->size());
- assert(!mr.is_empty(), "Error");
- if (_defer_initial_card_mark) {
- // Defer the card mark
- thread->set_deferred_card_mark(mr);
- } else {
- // Do the card mark
- BarrierSet* bs = barrier_set();
- bs->write_region(mr);
- }
- }
- return new_obj;
-}
-
size_t CollectedHeap::filler_array_hdr_size() {
return align_object_offset(arrayOopDesc::header_size(T_INT)); // align to Long
}
size_t CollectedHeap::filler_array_min_size() {
!is_init_completed(),
"Should only be called at a safepoint or at start-up"
" otherwise concurrent mutator activity may make heap "
" unparsable again");
const bool use_tlab = UseTLAB;
- const bool deferred = _defer_initial_card_mark;
// The main thread starts allocating via a TLAB even before it
// has added itself to the threads list at vm boot-up.
JavaThreadIteratorWithHandle jtiwh;
assert(!use_tlab || jtiwh.length() > 0,
"Attempt to fill tlabs before main thread has been added"
" to threads list is doomed to failure!");
+ BarrierSet *bs = barrier_set();
for (; JavaThread *thread = jtiwh.next(); ) {
if (use_tlab) thread->tlab().make_parsable(retire_tlabs);
-#if COMPILER2_OR_JVMCI
- // The deferred store barriers must all have been flushed to the
- // card-table (or other remembered set structure) before GC starts
- // processing the card-table (or other remembered set).
- if (deferred) flush_deferred_store_barrier(thread);
-#else
- assert(!deferred, "Should be false");
- assert(thread->deferred_card_mark().is_empty(), "Should be empty");
-#endif
+ bs->make_parsable(thread);
}
}
void CollectedHeap::accumulate_statistics_all_tlabs() {
if (UseTLAB) {
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