From c470ac79015ad99f1760784cbffcf4b92d5bc8dc Mon Sep 17 00:00:00 2001 From: DXwangg Date: Wed, 26 Oct 2022 12:52:55 +0800 Subject: [PATCH] qqqqq --- .../share/gc/parallel/parallel_globals.hpp | 6 +++++- .../gc/parallel/psPromotionManager.inline.hpp | 18 ++++++++++++++++-- 2 files changed, 21 insertions(+), 3 deletions(-) diff --git a/src/hotspot/share/gc/parallel/parallel_globals.hpp b/src/hotspot/share/gc/parallel/parallel_globals.hpp index 5461bf04f..75ee84d4f 100644 --- a/src/hotspot/share/gc/parallel/parallel_globals.hpp +++ b/src/hotspot/share/gc/parallel/parallel_globals.hpp @@ -78,6 +78,10 @@ "Delay in scheduling GC workers (in milliseconds)") \ \ product(bool, PSChunkLargeArrays, true, \ - "Process large arrays in chunks") + "Process large arrays in chunks") \ + \ + experimental(bool, UsePSRelaxedForwardee, false, \ + "Use the UsePSRelaxedForwardee to enable ps use relaxed" \ + "during young gc copying object") #endif // SHARE_GC_PARALLEL_PARALLEL_GLOBALS_HPP diff --git a/src/hotspot/share/gc/parallel/psPromotionManager.inline.hpp b/src/hotspot/share/gc/parallel/psPromotionManager.inline.hpp index cc5a4aa98..5a71ca307 100644 --- a/src/hotspot/share/gc/parallel/psPromotionManager.inline.hpp +++ b/src/hotspot/share/gc/parallel/psPromotionManager.inline.hpp @@ -35,6 +35,7 @@ #include "logging/log.hpp" #include "oops/access.inline.hpp" #include "oops/oop.inline.hpp" +#include "runtime/prefetch.inline.hpp" inline PSPromotionManager* PSPromotionManager::manager_array(uint index) { assert(_manager_array != NULL, "access of NULL manager_array"); @@ -214,12 +215,21 @@ inline oop PSPromotionManager::copy_to_survivor_space(oop o) { assert(new_obj != NULL, "allocation should have succeeded"); + Prefetch::write(new_obj, PrefetchCopyIntervalInBytes); + // Copy obj Copy::aligned_disjoint_words((HeapWord*)o, (HeapWord*)new_obj, new_obj_size); // Now we have to CAS in the header. - // Make copy visible to threads reading the forwardee. - if (o->cas_forward_to(new_obj, test_mark, o->klass()->oop_is_gc_leaf()? memory_order_relaxed : memory_order_release)) { + // When use relaxed CAS, cann't gurantee new obj visible for other threads accessing forwardee. + // As oop_is_gc_leaf is verified for long time without problems, for gc leaf's benefit, we add + // UsePSRelaxedForwardee to enable using relaxed CAS rather than delete oop_is_gc_leaf condition directly. +#ifdef PRODUCT + if (o->cas_forward_to(new_obj, test_mark, (UsePSRelaxedForwardee || o->klass()->oop_is_gc_leaf()) ? + memory_order_relaxed : memory_order_release)) { +#else + if (o->cas_forward_to(new_obj, test_mark, memory_order_release)) { +#endif // We won any races, we "own" this object. assert(new_obj == o->forwardee(), "Sanity"); @@ -275,6 +285,10 @@ inline oop PSPromotionManager::copy_to_survivor_space(oop o) { // This code must come after the CAS test, or it will print incorrect // information. + // When UsePSRelaxedForwardee is true or object o is gc leaf, CAS failed threads can't access forwardee's content, + // as relaxed CAS cann't gurantee new obj's content visible for these CAS failed threads.The below log output is + // dangerous.So we just support UsePSRelaxedForwardee and gc leaf in product. + // Everywhere access forwardee's content must be careful. log_develop_trace(gc, scavenge)("{%s %s " PTR_FORMAT " -> " PTR_FORMAT " (%d)}", should_scavenge(&new_obj) ? "copying" : "tenuring", new_obj->klass()->internal_name(), p2i((void *)o), p2i((void *)new_obj), new_obj->size()); -- 2.30.1 (Apple Git-130)