[heap] Evacuation for young generation

src/heap/spaces.cc

 // Copyright 2011 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/spaces.h"
 
 #include <utility>
 
 #include "src/base/bits.h"
 #include "src/base/platform/platform.h"
@@ skipping 1277 matching lines @@
     while ((p = collector->sweeper().GetSweptPageSafe(this)) != nullptr) {
       // Only during compaction pages can actually change ownership. This is
       // safe because there exists no other competing action on the page links
       // during compaction.
       if (is_local() && (p->owner() != this)) {
         base::LockGuard<base::Mutex> guard(
             reinterpret_cast<PagedSpace*>(p->owner())->mutex());
         p->Unlink();
         p->set_owner(this);
         p->InsertAfter(anchor_.prev_page());
+      } else {
+        CHECK_EQ(this, p->owner());
+        // Regular refill on main thread. Pages are already linked into the
+        // space but might require relinking.
+        if (p->available_in_free_list() < kPageReuseThreshold) {
+          // Relink categories with only little memory left previous to anchor.
+          p->Unlink();
+          p->InsertAfter(anchor()->prev_page());
+        }
       }
       added += RelinkFreeListCategories(p);
       added += p->wasted_memory();
       if (is_local() && (added > kCompactionMemoryWanted)) break;
     }
   }
   accounting_stats_.IncreaseCapacity(added);
 }
 
 void PagedSpace::MergeCompactionSpace(CompactionSpace* other) {
@@ skipping 16 matching lines @@
 
   // Move over pages.
   for (auto it = other->begin(); it != other->end();) {
     Page* p = *(it++);
 
     // Relinking requires the category to be unlinked.
     other->UnlinkFreeListCategories(p);
 
     p->Unlink();
     p->set_owner(this);
-    p->InsertAfter(anchor_.prev_page());
+    if (p->available_in_free_list() < kPageReuseThreshold) {
+      // Relink categories with only little memory left previous to anchor.
+      p->InsertAfter(anchor()->prev_page());
+    } else {
+      p->InsertAfter(anchor());
+    }
     RelinkFreeListCategories(p);
     DCHECK_EQ(p->AvailableInFreeList(), p->available_in_free_list());
   }
 }
 
 
 size_t PagedSpace::CommittedPhysicalMemory() {
   if (!base::VirtualMemory::HasLazyCommits()) return CommittedMemory();
   MemoryChunk::UpdateHighWaterMark(allocation_info_.top());
   size_t size = 0;
   for (Page* page : *this) {
     size += page->CommittedPhysicalMemory();
   }
   return size;
 }
 
 bool PagedSpace::ContainsSlow(Address addr) {
   Page* p = Page::FromAddress(addr);
   for (Page* page : *this) {
     if (page == p) return true;
   }
   return false;
 }
 
+Page* PagedSpace::RemovePageSafe() {
+  base::LockGuard<base::Mutex> guard(mutex());
+  Page* page = anchor()->next_page();
+
+  while (!page->CanUseForAllocation()) page = page->next_page();
+  if (page == anchor() || page->available_in_free_list() < kPageReuseThreshold)
+    return nullptr;
+
+  AccountUncommitted(page->size());
+  accounting_stats_.DeallocateBytes(page->LiveBytesFromFreeList());
+  accounting_stats_.DecreaseCapacity(page->area_size());
+  page->Unlink();
+  UnlinkFreeListCategories(page);
+  return page;
+}
+
+void PagedSpace::AddPage(Page* page) {
+  AccountCommitted(page->size());
+  accounting_stats_.IncreaseCapacity(page->area_size());
+  accounting_stats_.AllocateBytes(page->LiveBytesFromFreeList());
+  page->set_owner(this);
+  RelinkFreeListCategories(page);
+  page->InsertAfter(anchor()->prev_page());
+}
+
 void PagedSpace::ShrinkImmortalImmovablePages() {
   DCHECK(!heap()->deserialization_complete());
   MemoryChunk::UpdateHighWaterMark(allocation_info_.top());
   EmptyAllocationInfo();
   ResetFreeList();
 
   for (Page* page : *this) {
     DCHECK(page->IsFlagSet(Page::NEVER_EVACUATE));
     size_t unused = page->ShrinkToHighWaterMark();
     accounting_stats_.DecreaseCapacity(static_cast<intptr_t>(unused));
     AccountUncommitted(unused);
   }
 }
 
 bool PagedSpace::Expand() {
+  base::LockGuard<base::Mutex> guard(mutex());
+
   const int size = AreaSize();
 
   if (!heap()->CanExpandOldGeneration(size)) return false;
 
   Page* p = heap()->memory_allocator()->AllocatePage(size, this, executable());
   if (p == nullptr) return false;
 
   AccountCommitted(p->size());
 
   // Pages created during bootstrapping may contain immortal immovable objects.
@@ skipping 1527 matching lines @@
     if (object != NULL) return object;
 
     // If sweeping is still in progress try to sweep pages on the main thread.
     int max_freed = collector->sweeper().ParallelSweepSpace(
         identity(), size_in_bytes, kMaxPagesToSweep);
     RefillFreeList();
     if (max_freed >= size_in_bytes) {
       object = free_list_.Allocate(static_cast<size_t>(size_in_bytes));
       if (object != nullptr) return object;
     }
+  } else if (is_local()) {
+    // Sweeping not in progress and we are on a {CompactionSpace}. This can
+    // only happen when we are evacuating for the young generation.
+    PagedSpace* main_space = heap()->paged_space(identity());
+    Page* page = main_space->RemovePageSafe();
+    if (page != nullptr) {
+      AddPage(page);
+      HeapObject* object =
+          free_list_.Allocate(static_cast<size_t>(size_in_bytes));
+      if (object != nullptr) return object;
+    }
   }
 
   if (heap()->ShouldExpandOldGenerationOnSlowAllocation() && Expand()) {
     DCHECK((CountTotalPages() > 1) ||
            (static_cast<size_t>(size_in_bytes) <= free_list_.Available()));
     return free_list_.Allocate(static_cast<size_t>(size_in_bytes));
   }
 
   // If sweeper threads are active, wait for them at that point and steal
   // elements form their free-lists. Allocation may still fail their which
@@ skipping 383 matching lines @@
     PrintF("\n");
   }
   printf(" --------------------------------------\n");
   printf(" Marked: %x, LiveCount: %" V8PRIdPTR "\n", mark_size,
          MarkingState::Internal(this).live_bytes());
 }
 
 #endif  // DEBUG
 }  // namespace internal
 }  // namespace v8