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8060025: Object copy time regressions after JDK-8031323 and JDK-8057536

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Evaluate and improve object copy time by micro-optimizations and splitting out slow and fast paths aggressively.

Co-authored-by: Tony Printezis <tprintezis@twitter.com>
Reviewed-by: kbarrett, mgerdin, jmasa
This commit is contained in:
Thomas Schatzl 2014-12-19 09:21:06 +01:00
parent 093d2698fc
commit 1be86b3412
14 changed files with 491 additions and 284 deletions
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132
hotspot/src/share/vm/gc_implementation/g1/g1ParScanThreadState.cpp
View file

@ -38,6 +38,7 @@ G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num,
_g1_rem(g1h->g1_rem_set()),
_hash_seed(17), _queue_num(queue_num),
_term_attempts(0),
_tenuring_threshold(g1h->g1_policy()->tenuring_threshold()),
_age_table(false), _scanner(g1h, rp),
_strong_roots_time(0), _term_time(0) {
_scanner.set_par_scan_thread_state(this);
@ -59,6 +60,12 @@ G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num,
_g1_par_allocator = G1ParGCAllocator::create_allocator(_g1h);
_dest[InCSetState::NotInCSet] = InCSetState::NotInCSet;
// The dest for Young is used when the objects are aged enough to
// need to be moved to the next space.
_dest[InCSetState::Young] = InCSetState::Old;
_dest[InCSetState::Old] = InCSetState::Old;
_start = os::elapsedTime();
}
@ -150,52 +157,94 @@ void G1ParScanThreadState::trim_queue() {
} while (!_refs->is_empty());
}
oop G1ParScanThreadState::copy_to_survivor_space(oop const old,
HeapWord* G1ParScanThreadState::allocate_in_next_plab(InCSetState const state,
InCSetState* dest,
size_t word_sz,
AllocationContext_t const context) {
assert(state.is_in_cset_or_humongous(), err_msg("Unexpected state: " CSETSTATE_FORMAT, state.value()));
assert(dest->is_in_cset_or_humongous(), err_msg("Unexpected dest: " CSETSTATE_FORMAT, dest->value()));
// Right now we only have two types of regions (young / old) so
// let's keep the logic here simple. We can generalize it when necessary.
if (dest->is_young()) {
HeapWord* const obj_ptr = _g1_par_allocator->allocate(InCSetState::Old,
word_sz, context);
if (obj_ptr == NULL) {
return NULL;
}
// Make sure that we won't attempt to copy any other objects out
// of a survivor region (given that apparently we cannot allocate
// any new ones) to avoid coming into this slow path.
_tenuring_threshold = 0;
dest->set_old();
return obj_ptr;
} else {
assert(dest->is_old(), err_msg("Unexpected dest: " CSETSTATE_FORMAT, dest->value()));
// no other space to try.
return NULL;
}
}
InCSetState G1ParScanThreadState::next_state(InCSetState const state, markOop const m, uint& age) {
if (state.is_young()) {
age = !m->has_displaced_mark_helper() ? m->age()
: m->displaced_mark_helper()->age();
if (age < _tenuring_threshold) {
return state;
}
}
return dest(state);
}
oop G1ParScanThreadState::copy_to_survivor_space(InCSetState const state,
oop const old,
markOop const old_mark) {
size_t word_sz = old->size();
HeapRegion* from_region = _g1h->heap_region_containing_raw(old);
const size_t word_sz = old->size();
HeapRegion* const from_region = _g1h->heap_region_containing_raw(old);
// +1 to make the -1 indexes valid...
int young_index = from_region->young_index_in_cset()+1;
const int young_index = from_region->young_index_in_cset()+1;
assert( (from_region->is_young() && young_index > 0) ||
(!from_region->is_young() && young_index == 0), "invariant" );
G1CollectorPolicy* g1p = _g1h->g1_policy();
uint age = old_mark->has_displaced_mark_helper() ? old_mark->displaced_mark_helper()->age()
: old_mark->age();
GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
word_sz);
AllocationContext_t context = from_region->allocation_context();
HeapWord* obj_ptr = _g1_par_allocator->allocate(alloc_purpose, word_sz, context);
const AllocationContext_t context = from_region->allocation_context();
uint age = 0;
InCSetState dest_state = next_state(state, old_mark, age);
HeapWord* obj_ptr = _g1_par_allocator->plab_allocate(dest_state, word_sz, context);
// PLAB allocations should succeed most of the time, so we'll
// normally check against NULL once and that's it.
if (obj_ptr == NULL) {
obj_ptr = _g1_par_allocator->allocate_direct_or_new_plab(dest_state, word_sz, context);
if (obj_ptr == NULL) {
obj_ptr = allocate_in_next_plab(state, &dest_state, word_sz, context);
if (obj_ptr == NULL) {
// This will either forward-to-self, or detect that someone else has
// installed a forwarding pointer.
return _g1h->handle_evacuation_failure_par(this, old);
}
}
}
assert(obj_ptr != NULL, "when we get here, allocation should have succeeded");
#ifndef PRODUCT
// Should this evacuation fail?
if (_g1h->evacuation_should_fail()) {
if (obj_ptr != NULL) {
_g1_par_allocator->undo_allocation(alloc_purpose, obj_ptr, word_sz, context);
obj_ptr = NULL;
}
}
#endif // !PRODUCT
if (obj_ptr == NULL) {
// This will either forward-to-self, or detect that someone else has
// installed a forwarding pointer.
// Doing this after all the allocation attempts also tests the
// undo_allocation() method too.
_g1_par_allocator->undo_allocation(dest_state, obj_ptr, word_sz, context);
return _g1h->handle_evacuation_failure_par(this, old);
}
oop obj = oop(obj_ptr);
#endif // !PRODUCT
// We're going to allocate linearly, so might as well prefetch ahead.
Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
oop forward_ptr = old->forward_to_atomic(obj);
const oop obj = oop(obj_ptr);
const oop forward_ptr = old->forward_to_atomic(obj);
if (forward_ptr == NULL) {
Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
// alloc_purpose is just a hint to allocate() above, recheck the type of region
// we actually allocated from and update alloc_purpose accordingly
HeapRegion* to_region = _g1h->heap_region_containing_raw(obj_ptr);
alloc_purpose = to_region->is_young() ? GCAllocForSurvived : GCAllocForTenured;
if (g1p->track_object_age(alloc_purpose)) {
if (dest_state.is_young()) {
if (age < markOopDesc::max_age) {
age++;
}
@ -215,13 +264,19 @@ oop G1ParScanThreadState::copy_to_survivor_space(oop const old,
}
if (G1StringDedup::is_enabled()) {
G1StringDedup::enqueue_from_evacuation(from_region->is_young(),
to_region->is_young(),
const bool is_from_young = state.is_young();
const bool is_to_young = dest_state.is_young();
assert(is_from_young == _g1h->heap_region_containing_raw(old)->is_young(),
"sanity");
assert(is_to_young == _g1h->heap_region_containing_raw(obj)->is_young(),
"sanity");
G1StringDedup::enqueue_from_evacuation(is_from_young,
is_to_young,
queue_num(),
obj);
}
size_t* surv_young_words = surviving_young_words();
size_t* const surv_young_words = surviving_young_words();
surv_young_words[young_index] += word_sz;
if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
@ -232,14 +287,13 @@ oop G1ParScanThreadState::copy_to_survivor_space(oop const old,
oop* old_p = set_partial_array_mask(old);
push_on_queue(old_p);
} else {
// No point in using the slower heap_region_containing() method,
// given that we know obj is in the heap.
_scanner.set_region(_g1h->heap_region_containing_raw(obj));
HeapRegion* const to_region = _g1h->heap_region_containing_raw(obj_ptr);
_scanner.set_region(to_region);
obj->oop_iterate_backwards(&_scanner);
}
return obj;
} else {
_g1_par_allocator->undo_allocation(alloc_purpose, obj_ptr, word_sz, context);
obj = forward_ptr;
_g1_par_allocator->undo_allocation(dest_state, obj_ptr, word_sz, context);
return forward_ptr;
}
return obj;
}