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Remove necessary atomic load

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This commit is contained in:
Xiaolong Peng 2026-01-09 11:01:09 -08:00
parent dc0645549a
commit 5e8f5998cb
2 changed files with 9 additions and 12 deletions
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17
src/hotspot/share/gc/shenandoah/shenandoahAllocator.cpp
View File

@ -122,7 +122,7 @@ template <ShenandoahFreeSetPartitionId ALLOC_PARTITION>
HeapWord* ShenandoahAllocator<ALLOC_PARTITION>::attempt_allocation_slow(ShenandoahAllocRequest& req, bool& in_new_region, uint regions_ready_for_refresh, uint32_t old_epoch_id) {
ShenandoahHeapLocker locker(ShenandoahHeap::heap()->lock(), _yield_to_safepoint);
HeapWord* obj = nullptr;
if (old_epoch_id != AtomicAccess::load(&_epoch_id)) {
if (old_epoch_id != _epoch_id) {
// After taking heap lock, attempt to allocate in shared alloc regions again
// if alloc regions have been refreshed by other thread while current thread waits to take heap lock.
regions_ready_for_refresh = 0u; //reset regions_ready_for_refresh to 0.
@ -203,7 +203,8 @@ HeapWord* ShenandoahAllocator<ALLOC_PARTITION>::attempt_allocation_in_alloc_regi
if (obj != nullptr) {
return obj;
}
} else if (r == nullptr || !r->is_active_alloc_region()) {
} else {
// Empty shared alloc region slot is always ready for refresh
regions_ready_for_refresh++;
}
if (++i == _alloc_region_count) {
@ -266,11 +267,9 @@ int ShenandoahAllocator<ALLOC_PARTITION>::refresh_alloc_regions(ShenandoahAllocR
ShenandoahAllocRegion* alloc_region = &_alloc_regions[i];
ShenandoahHeapRegion* region = alloc_region->address;
const size_t free_bytes = region == nullptr ? 0 : region->free();
if (region == nullptr || !region->is_active_alloc_region() || free_bytes / HeapWordSize < PLAB::min_size()) {
if (region == nullptr || free_bytes / HeapWordSize < PLAB::min_size()) {
if (region != nullptr) {
if (region->is_active_alloc_region()) {
region->unset_active_alloc_region();
}
region->unset_active_alloc_region();
log_debug(gc, alloc)("%sAllocator: Removing heap region %li from alloc region %i.",
_alloc_partition_name, region->index(), alloc_region->alloc_region_index);
AtomicAccess::store(&alloc_region->address, static_cast<ShenandoahHeapRegion*>(nullptr));
@ -353,10 +352,8 @@ void ShenandoahAllocator<ALLOC_PARTITION>::release_alloc_regions() {
if (r != nullptr) {
log_debug(gc, alloc)("%sAllocator: Releasing heap region %li from alloc region %i",
_alloc_partition_name, r->index(), i);
if (r->is_active_alloc_region()) {
r->unset_active_alloc_region();
}
AtomicAccess::store(&alloc_region.address, static_cast<ShenandoahHeapRegion*>(nullptr));
r->unset_active_alloc_region();
alloc_region.address = nullptr;
size_t free_bytes = r->free();
if (free_bytes >= PLAB::min_size_bytes()) {
total_free_bytes += free_bytes;

4
src/hotspot/share/gc/shenandoah/shenandoahHeapRegion.inline.hpp
View File

@ -170,7 +170,7 @@ HeapWord* ShenandoahHeapRegion::allocate_atomic(size_t size, const ShenandoahAll
assert(this->is_regular() || this->is_regular_pinned(), "must be a regular region");
ShenandoahHeapRegionReadyForRetireChecker retire_checker(ready_for_retire);
for (;;) {
for (;/*Always return in the loop*/;) {
HeapWord* obj = top();
size_t free_words = pointer_delta( end(), obj);
if (free_words >= size) {
@ -193,7 +193,7 @@ HeapWord* ShenandoahHeapRegion::allocate_lab_atomic(const ShenandoahAllocRequest
assert(this->is_regular() || this->is_regular_pinned(), "must be a regular region");
ShenandoahHeapRegionReadyForRetireChecker retire_checker(ready_for_retire);
for (;;) {
for (;/*Always return in the loop*/;) {
size_t adjusted_size = req.size();
HeapWord* obj = top();
size_t free_words = pointer_delta(end(), obj);