diff --git a/src/hotspot/share/gc/g1/g1ConcurrentMark.hpp b/src/hotspot/share/gc/g1/g1ConcurrentMark.hpp index 1a0cfcd8caa..7ea9151c6f1 100644 --- a/src/hotspot/share/gc/g1/g1ConcurrentMark.hpp +++ b/src/hotspot/share/gc/g1/g1ConcurrentMark.hpp @@ -557,14 +557,14 @@ public: // mark_in_bitmap call. Updates various statistics data. void add_to_liveness(uint worker_id, oop const obj, size_t size); // Did the last marking find a live object between bottom and TAMS? - bool contains_live_object(uint region) const { return _region_mark_stats[region]._live_words != 0; } + bool contains_live_object(uint region) const { return _region_mark_stats[region].live_words() != 0; } // Live bytes in the given region as determined by concurrent marking, i.e. the amount of // live bytes between bottom and TAMS. - size_t live_bytes(uint region) const { return _region_mark_stats[region]._live_words * HeapWordSize; } + size_t live_bytes(uint region) const { return _region_mark_stats[region].live_words() * HeapWordSize; } // Set live bytes for concurrent marking. - void set_live_bytes(uint region, size_t live_bytes) { _region_mark_stats[region]._live_words = live_bytes / HeapWordSize; } + void set_live_bytes(uint region, size_t live_bytes) { _region_mark_stats[region]._live_words.store_relaxed(live_bytes / HeapWordSize); } // Approximate number of incoming references found during marking. - size_t incoming_refs(uint region) const { return _region_mark_stats[region]._incoming_refs; } + size_t incoming_refs(uint region) const { return _region_mark_stats[region].incoming_refs(); } // Update the TAMS for the given region to the current top. inline void update_top_at_mark_start(G1HeapRegion* r); diff --git a/src/hotspot/share/gc/g1/g1FullCollector.hpp b/src/hotspot/share/gc/g1/g1FullCollector.hpp index ed8225fc004..1fb3af17032 100644 --- a/src/hotspot/share/gc/g1/g1FullCollector.hpp +++ b/src/hotspot/share/gc/g1/g1FullCollector.hpp @@ -1,5 +1,5 @@ /* - * Copyright (c) 2017, 2025, Oracle and/or its affiliates. All rights reserved. + * Copyright (c) 2017, 2026, 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 @@ -122,7 +122,7 @@ public: ReferenceProcessor* reference_processor(); size_t live_words(uint region_index) const { assert(region_index < _heap->max_num_regions(), "sanity"); - return _live_stats[region_index]._live_words; + return _live_stats[region_index].live_words(); } void before_marking_update_attribute_table(G1HeapRegion* hr); diff --git a/src/hotspot/share/gc/g1/g1RegionMarkStatsCache.hpp b/src/hotspot/share/gc/g1/g1RegionMarkStatsCache.hpp index 3c1a6ed4667..4dcdd33846e 100644 --- a/src/hotspot/share/gc/g1/g1RegionMarkStatsCache.hpp +++ b/src/hotspot/share/gc/g1/g1RegionMarkStatsCache.hpp @@ -1,5 +1,5 @@ /* - * Copyright (c) 2018, 2025, Oracle and/or its affiliates. All rights reserved. + * Copyright (c) 2018, 2026, 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 @@ -27,6 +27,7 @@ #include "memory/allocation.hpp" #include "oops/oop.hpp" +#include "runtime/atomic.hpp" #include "utilities/debug.hpp" #include "utilities/globalDefinitions.hpp" #include "utilities/pair.hpp" @@ -40,20 +41,23 @@ // * the number of incoming references found during marking. This is an approximate // value because we do not mark through all objects. struct G1RegionMarkStats { - size_t _live_words; - size_t _incoming_refs; + Atomic _live_words; + Atomic _incoming_refs; // Clear all members. void clear() { - _live_words = 0; - _incoming_refs = 0; + _live_words.store_relaxed(0); + _incoming_refs.store_relaxed(0); } // Clear all members after a marking overflow. Only needs to clear the number of // incoming references as all objects will be rescanned, while the live words are // gathered whenever a thread can mark an object, which is synchronized. void clear_during_overflow() { - _incoming_refs = 0; + _incoming_refs.store_relaxed(0); } + + size_t live_words() const { return _live_words.load_relaxed(); } + size_t incoming_refs() const { return _incoming_refs.load_relaxed(); } }; // Per-marking thread cache for the region mark statistics. @@ -112,12 +116,16 @@ public: void add_live_words(oop obj); void add_live_words(uint region_idx, size_t live_words) { G1RegionMarkStatsCacheEntry* const cur = find_for_add(region_idx); - cur->_stats._live_words += live_words; + // This method is only ever called single-threaded, so we do not need atomic + // update here. + cur->_stats._live_words.store_relaxed(cur->_stats.live_words() + live_words); } void inc_incoming_refs(uint region_idx) { G1RegionMarkStatsCacheEntry* const cur = find_for_add(region_idx); - cur->_stats._incoming_refs++; + // This method is only ever called single-threaded, so we do not need atomic + // update here. + cur->_stats._incoming_refs.store_relaxed(cur->_stats.incoming_refs() + 1u); } void reset(uint region_idx) { diff --git a/src/hotspot/share/gc/g1/g1RegionMarkStatsCache.inline.hpp b/src/hotspot/share/gc/g1/g1RegionMarkStatsCache.inline.hpp index 6b0ebb34e0d..71cd33e71ae 100644 --- a/src/hotspot/share/gc/g1/g1RegionMarkStatsCache.inline.hpp +++ b/src/hotspot/share/gc/g1/g1RegionMarkStatsCache.inline.hpp @@ -1,5 +1,5 @@ /* - * Copyright (c) 2018, 2025, Oracle and/or its affiliates. All rights reserved. + * Copyright (c) 2018, 2026, 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 @@ -27,8 +27,6 @@ #include "gc/g1/g1RegionMarkStatsCache.hpp" -#include "runtime/atomicAccess.hpp" - inline G1RegionMarkStatsCache::G1RegionMarkStatsCacheEntry* G1RegionMarkStatsCache::find_for_add(uint region_idx) { uint const cache_idx = hash(region_idx); @@ -46,12 +44,12 @@ inline G1RegionMarkStatsCache::G1RegionMarkStatsCacheEntry* G1RegionMarkStatsCac inline void G1RegionMarkStatsCache::evict(uint idx) { G1RegionMarkStatsCacheEntry* cur = &_cache[idx]; - if (cur->_stats._live_words != 0) { - AtomicAccess::add(&_target[cur->_region_idx]._live_words, cur->_stats._live_words); + if (cur->_stats.live_words() != 0) { + _target[cur->_region_idx]._live_words.add_then_fetch(cur->_stats.live_words()); } - if (cur->_stats._incoming_refs != 0) { - AtomicAccess::add(&_target[cur->_region_idx]._incoming_refs, cur->_stats._incoming_refs); + if (cur->_stats.incoming_refs() != 0) { + _target[cur->_region_idx]._incoming_refs.add_then_fetch(cur->_stats.incoming_refs()); } cur->clear();