[heap] Eliminate fast promotion mode

Bug: v8:12612
Change-Id: Iaf967da524413b6701aa93fa471d79e2a82e43e2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3805064Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82147}

BUILD.bazel

@@ -1524,8 +1524,6 @@ filegroup(
         "src/heap/parallel-work-item.h",
         "src/heap/parked-scope.h",
         "src/heap/progress-bar.h",
-        "src/heap/promote-young-generation.cc",
-        "src/heap/promote-young-generation.h",
         "src/heap/read-only-heap-inl.h",
         "src/heap/read-only-heap.cc",
         "src/heap/read-only-heap.h",

BUILD.gn

@@ -3159,7 +3159,6 @@ v8_header_set("v8_internal_headers") {
     "src/heap/parallel-work-item.h",
     "src/heap/parked-scope.h",
     "src/heap/progress-bar.h",
-    "src/heap/promote-young-generation.h",
     "src/heap/read-only-heap-inl.h",
     "src/heap/read-only-heap.h",
     "src/heap/read-only-spaces.h",
@@ -4523,7 +4522,6 @@ v8_source_set("v8_base_without_compiler") {
     "src/heap/object-stats.cc",
     "src/heap/objects-visiting.cc",
     "src/heap/paged-spaces.cc",
-    "src/heap/promote-young-generation.cc",
     "src/heap/read-only-heap.cc",
     "src/heap/read-only-spaces.cc",
     "src/heap/safepoint.cc",

src/flags/flag-definitions.h

@@ -1464,8 +1464,6 @@ DEFINE_BOOL(randomize_all_allocations, false,
 DEFINE_BOOL(manual_evacuation_candidates_selection, false,
             "Test mode only flag. It allows an unit test to select evacuation "
             "candidates pages (requires --stress_compaction).")
-DEFINE_BOOL(fast_promotion_new_space, false,
-            "fast promote new space on high survival rates")
 
 DEFINE_BOOL(clear_free_memory, false, "initialize free memory with 0")
 

src/heap/heap.cc

@@ -71,7 +71,6 @@
 #include "src/heap/objects-visiting.h"
 #include "src/heap/paged-spaces-inl.h"
 #include "src/heap/parked-scope.h"
-#include "src/heap/promote-young-generation.h"
 #include "src/heap/read-only-heap.h"
 #include "src/heap/remembered-set.h"
 #include "src/heap/safepoint.h"
@@ -2294,8 +2293,6 @@ size_t Heap::PerformGarbageCollection(
 
   if (collector == GarbageCollector::MARK_COMPACTOR) {
     MarkCompact();
-  } else if (fast_promotion_mode_ && CanPromoteYoungAndExpandOldGeneration(0)) {
-    PromoteYoungGeneration();
   } else if (collector == GarbageCollector::MINOR_MARK_COMPACTOR) {
     MinorMarkCompact();
   } else {
@@ -2315,10 +2312,6 @@ size_t Heap::PerformGarbageCollection(
         start_young_generation_size - SurvivedYoungObjectSize());
   }
 
-  if (!fast_promotion_mode_ || collector == GarbageCollector::MARK_COMPACTOR) {
-    ComputeFastPromotionMode();
-  }
-
   isolate_->counters()->objs_since_last_young()->Set(0);
 
   isolate_->eternal_handles()->PostGarbageCollectionProcessing();
@@ -2674,12 +2667,6 @@ void Heap::CheckNewSpaceExpansionCriteria() {
   new_lo_space()->SetCapacity(new_space()->Capacity());
 }
 
-void Heap::PromoteYoungGeneration() {
-  tracer()->NotifyYoungGenerationHandling(
-      YoungGenerationHandling::kFastPromotionDuringScavenge);
-  promote_young_generation_gc_->EvacuateYoungGeneration();
-}
-
 void Heap::Scavenge() {
   DCHECK_NOT_NULL(new_space());
   DCHECK_IMPLIES(FLAG_separate_gc_phases, !incremental_marking()->IsMarking());
@@ -2734,23 +2721,6 @@ void Heap::Scavenge() {
   SetGCState(NOT_IN_GC);
 }
 
-void Heap::ComputeFastPromotionMode() {
-  if (!new_space_) return;
-
-  const size_t survived_in_new_space =
-      survived_last_scavenge_ * 100 / NewSpaceCapacity();
-  fast_promotion_mode_ =
-      !FLAG_optimize_for_size && FLAG_fast_promotion_new_space &&
-      !ShouldReduceMemory() && new_space_->IsAtMaximumCapacity() &&
-      survived_in_new_space >= kMinPromotedPercentForFastPromotionMode;
-
-  if (FLAG_trace_gc_verbose && !FLAG_trace_gc_ignore_scavenger) {
-    PrintIsolate(isolate(), "Fast promotion mode: %s survival rate: %zu%%\n",
-                 fast_promotion_mode_ ? "true" : "false",
-                 survived_in_new_space);
-  }
-}
-
 void Heap::UnprotectAndRegisterMemoryChunk(MemoryChunk* chunk,
                                            UnprotectMemoryOrigin origin) {
   if (!write_protect_code_memory()) return;
@@ -5716,7 +5686,6 @@ void Heap::SetUp(LocalHeap* main_thread_local_heap) {
   mark_compact_collector_.reset(new MarkCompactCollector(this));
 
   scavenger_collector_.reset(new ScavengerCollector(this));
-  promote_young_generation_gc_.reset(new PromoteYoungGenerationGC(this));
   minor_mark_compact_collector_.reset(new MinorMarkCompactCollector(this));
 
   incremental_marking_.reset(
@@ -6131,7 +6100,6 @@ void Heap::TearDown() {
   }
 
   scavenger_collector_.reset();
-  promote_young_generation_gc_.reset();
   array_buffer_sweeper_.reset();
   incremental_marking_.reset();
   concurrent_marking_.reset();

src/heap/heap.h

@@ -110,7 +110,6 @@ class ObjectIterator;
 class ObjectStats;
 class Page;
 class PagedSpace;
-class PromoteYoungGenerationGC;
 class ReadOnlyHeap;
 class RootVisitor;
 class RwxMemoryWriteScope;
@@ -1907,8 +1906,6 @@ class Heap {
 
   bool InvokeNearHeapLimitCallback();
 
-  void ComputeFastPromotionMode();
-
   void InvokeIncrementalMarkingPrologueCallbacks();
   void InvokeIncrementalMarkingEpilogueCallbacks();
 
@@ -1947,7 +1944,6 @@ class Heap {
 
   // Performs a minor collection in new generation.
   void Scavenge();
-  void PromoteYoungGeneration();
 
   void UpdateYoungReferencesInExternalStringTable(
       ExternalStringTableUpdaterCallback updater_func);
@@ -2320,7 +2316,6 @@ class Heap {
   std::unique_ptr<MarkCompactCollector> mark_compact_collector_;
   std::unique_ptr<MinorMarkCompactCollector> minor_mark_compact_collector_;
   std::unique_ptr<ScavengerCollector> scavenger_collector_;
-  std::unique_ptr<PromoteYoungGenerationGC> promote_young_generation_gc_;
   std::unique_ptr<ArrayBufferSweeper> array_buffer_sweeper_;
 
   std::unique_ptr<MemoryAllocator> memory_allocator_;
@@ -2425,8 +2420,6 @@ class Heap {
 
   int max_regular_code_object_size_ = 0;
 
-  bool fast_promotion_mode_ = false;
-
   // Used for testing purposes.
   bool force_oom_ = false;
   bool force_gc_on_next_allocation_ = false;
@@ -2480,7 +2473,6 @@ class Heap {
   friend class ObjectStatsCollector;
   friend class Page;
   friend class PagedSpaceBase;
-  friend class PromoteYoungGenerationGC;
   friend class ReadOnlyRoots;
   friend class Scavenger;
   friend class ScavengerCollector;

src/heap/promote-young-generation.cc

-// Copyright 2022 the V8 project authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "src/heap/promote-young-generation.h"
-
-#include "src/heap/concurrent-marking.h"
-#include "src/heap/cppgc-js/cpp-heap.h"
-#include "src/heap/gc-tracer-inl.h"
-#include "src/heap/heap.h"
-#include "src/heap/incremental-marking.h"
-#include "src/heap/large-spaces.h"
-#include "src/heap/mark-compact.h"
-#include "src/heap/new-spaces.h"
-#include "src/heap/paged-spaces-inl.h"
-
-namespace v8 {
-namespace internal {
-
-void PromoteYoungGenerationGC::EvacuateYoungGeneration() {
-  TRACE_GC(heap_->tracer(), GCTracer::Scope::SCAVENGER_FAST_PROMOTE);
-  base::MutexGuard guard(heap_->relocation_mutex());
-  // Young generation garbage collection is orthogonal from full GC marking. It
-  // is possible that objects that are currently being processed for marking are
-  // reclaimed in the young generation GC that interleaves concurrent marking.
-  // Pause concurrent markers to allow processing them using
-  // `UpdateMarkingWorklistAfterYoungGenGC()`.
-  ConcurrentMarking::PauseScope pause_js_marking(heap_->concurrent_marking());
-  CppHeap::PauseConcurrentMarkingScope pause_cpp_marking(
-      CppHeap::From(heap_->cpp_heap()));
-  if (!FLAG_concurrent_marking) {
-    DCHECK(heap_->fast_promotion_mode_);
-    DCHECK(heap_->CanPromoteYoungAndExpandOldGeneration(0));
-  }
-
-  NewSpace* new_space = heap_->new_space();
-  // Move pages from new->old generation.
-  PageRange range(new_space->first_allocatable_address(), new_space->top());
-  for (auto it = range.begin(); it != range.end();) {
-    Page* p = (*++it)->prev_page();
-    new_space->PromotePageToOldSpace(p);
-    if (heap_->incremental_marking()->IsMarking())
-      heap_->mark_compact_collector()->RecordLiveSlotsOnPage(p);
-    p->ClearFlag(Page::PAGE_NEW_OLD_PROMOTION);
-  }
-
-  // Reset new space.
-  new_space->EvacuatePrologue();
-  if (!new_space->EnsureCurrentCapacity()) {
-    V8::FatalProcessOutOfMemory(
-        heap_->isolate(), "NewSpace::EnsureCurrentCapacity", V8::kHeapOOM);
-  }
-  new_space->EvacuateEpilogue();
-
-  for (auto it = heap_->new_lo_space()->begin();
-       it != heap_->new_lo_space()->end();) {
-    LargePage* page = *it;
-    // Increment has to happen after we save the page, because it is going to
-    // be removed below.
-    it++;
-    heap_->lo_space()->PromoteNewLargeObject(page);
-  }
-
-  // Fix up special trackers.
-  heap_->external_string_table_.PromoteYoung();
-  // GlobalHandles are updated in PostGarbageCollectionProcessing
-
-  size_t promoted = heap_->new_space()->Size() + heap_->new_lo_space()->Size();
-  heap_->IncrementYoungSurvivorsCounter(promoted);
-  heap_->IncrementPromotedObjectsSize(promoted);
-  heap_->IncrementSemiSpaceCopiedObjectSize(0);
-}
-
-}  // namespace internal
-}  // namespace v8

src/heap/promote-young-generation.h

-// Copyright 2022 the V8 project authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef V8_HEAP_PROMOTE_YOUNG_GENERATION_H_
-#define V8_HEAP_PROMOTE_YOUNG_GENERATION_H_
-
-namespace v8 {
-namespace internal {
-
-class Heap;
-
-/**
- * `PromoteYoungGenerationGC` is a special GC mode used in fast promotion mode
- * to quickly promote all objects in new space to old space, thus evacuating all
- * of new space and leaving it empty.
- */
-class PromoteYoungGenerationGC {
- public:
-  explicit PromoteYoungGenerationGC(Heap* heap) : heap_(heap) {}
-  void EvacuateYoungGeneration();
-
- private:
-  Heap* const heap_;
-};
-
-}  // namespace internal
-}  // namespace v8
-
-#endif  // V8_HEAP_PROMOTE_YOUNG_GENERATION_H_