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8259231: Epsilon: improve performance under contention during virtual space expansion

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Reviewed-by: shade
This commit is contained in:
Lehua Ding 2021-01-06 15:36:57 +00:00 committed by Aleksey Shipilev
parent f6cb8c558b
commit 722f23610e
1 changed files with 36 additions and 23 deletions
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59
src/hotspot/share/gc/epsilon/epsilonHeap.cpp
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@ -106,31 +106,44 @@ EpsilonHeap* EpsilonHeap::heap() {
HeapWord* EpsilonHeap::allocate_work(size_t size) {
assert(is_object_aligned(size), "Allocation size should be aligned: " SIZE_FORMAT, size);
HeapWord* res = _space->par_allocate(size);
while (res == NULL) {
// Allocation failed, attempt expansion, and retry:
MutexLocker ml(Heap_lock);
size_t space_left = max_capacity() - capacity();
size_t want_space = MAX2(size, EpsilonMinHeapExpand);
if (want_space < space_left) {
// Enough space to expand in bulk:
bool expand = _virtual_space.expand_by(want_space);
assert(expand, "Should be able to expand");
} else if (size < space_left) {
// No space to expand in bulk, and this allocation is still possible,
// take all the remaining space:
bool expand = _virtual_space.expand_by(space_left);
assert(expand, "Should be able to expand");
} else {
// No space left:
return NULL;
HeapWord* res = NULL;
while (true) {
// Try to allocate, assume space is available
res = _space->par_allocate(size);
if (res != NULL) {
break;
}
_space->set_end((HeapWord *) _virtual_space.high());
res = _space->par_allocate(size);
// Allocation failed, attempt expansion, and retry:
{
MutexLocker ml(Heap_lock);
// Try to allocate under the lock, assume another thread was able to expand
res = _space->par_allocate(size);
if (res != NULL) {
break;
}
// Expand and loop back if space is available
size_t space_left = max_capacity() - capacity();
size_t want_space = MAX2(size, EpsilonMinHeapExpand);
if (want_space < space_left) {
// Enough space to expand in bulk:
bool expand = _virtual_space.expand_by(want_space);
assert(expand, "Should be able to expand");
} else if (size < space_left) {
// No space to expand in bulk, and this allocation is still possible,
// take all the remaining space:
bool expand = _virtual_space.expand_by(space_left);
assert(expand, "Should be able to expand");
} else {
// No space left:
return NULL;
}
_space->set_end((HeapWord *) _virtual_space.high());
}
}
size_t used = _space->used();