[heap] Divide available memory upon compaction tasks

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 "src/base/bits.h"
 #include "src/base/platform/platform.h"
 #include "src/full-codegen/full-codegen.h"
 #include "src/heap/slots-buffer.h"
@@ skipping 964 matching lines @@
   PageIterator iterator(this);
   while (iterator.has_next()) {
     heap()->isolate()->memory_allocator()->Free(iterator.next());
   }
   anchor_.set_next_page(&anchor_);
   anchor_.set_prev_page(&anchor_);
   accounting_stats_.Clear();
 }
 
 
+void PagedSpace::AddMemory(Address start, intptr_t size) {
+  accounting_stats_.ExpandSpace(static_cast<int>(size));
+  Free(start, static_cast<int>(size));
+}
+
+
+FreeSpace* PagedSpace::TryRemoveMemory(intptr_t size_in_bytes) {
+  FreeSpace* space = free_list()->TryRemoveMemory(size_in_bytes);
+  if (space != nullptr) {
+    accounting_stats_.DecreaseCapacity(space->size());
+  }
+  return space;
+}
+
+
+void PagedSpace::DivideUponCompactionSpaces(CompactionSpaceCollection** other,
+                                            int num, intptr_t limit) {
+  DCHECK_GT(num, 0);
+  DCHECK(other != nullptr);
+
+  if (limit == 0) limit = std::numeric_limits<intptr_t>::max();
+
+  EmptyAllocationInfo();
+
+  bool memory_available = true;
+  bool spaces_need_memory = true;
+  FreeSpace* node = nullptr;
+  int index = 0;
+  CompactionSpace* current_space = nullptr;
+  // Iterate over spaces and memory as long as we have memory and there are
+  // spaces in need of some.
+  while (memory_available && spaces_need_memory) {
+    spaces_need_memory = false;
+    // Round-robin over all spaces.
+    for (int i = 0; i < num; i++) {
+      current_space = other[index]->Get(identity());
+      if (current_space->free_list()->available() < limit) {
+        // Space has not reached its limit. Try to get some memory.
+        spaces_need_memory = true;
+        node = TryRemoveMemory(limit - current_space->free_list()->available());
+        if (node != nullptr) {
+          CHECK(current_space->identity() == identity());
+          current_space->AddMemory(node->address(), node->size());
+        } else {
+          memory_available = false;
+          break;
+        }
+      }
+    }
+  }
+}
+
+
 void PagedSpace::MoveOverFreeMemory(PagedSpace* other) {
   DCHECK(identity() == other->identity());
   // Destroy the linear allocation space of {other}. This is needed to
   //   (a) not waste the memory and
   //   (b) keep the rest of the chunk in an iterable state (filler is needed).
   other->EmptyAllocationInfo();
 
   // Move over the free list. Concatenate makes sure that the source free list
   // gets properly reset after moving over all nodes.
   intptr_t added = free_list_.Concatenate(other->free_list());
 
   // Moved memory is not recorded as allocated memory, but rather increases and
-  // decreases capacity of the corresponding spaces. Used size and waste size
-  // are maintained by the receiving space upon allocating and freeing blocks.
+  // decreases capacity of the corresponding spaces.
   other->accounting_stats_.DecreaseCapacity(added);
   accounting_stats_.IncreaseCapacity(added);
 }
 
 
 void PagedSpace::MergeCompactionSpace(CompactionSpace* other) {
   // Unmerged fields:
   //   area_size_
-  //   allocation_info_
-  //   end_of_unswept_pages_
-  //   unswept_free_bytes_
   //   anchor_
 
   MoveOverFreeMemory(other);
 
   // Update and clear accounting statistics.
   accounting_stats_.Merge(other->accounting_stats_);
-  other->accounting_stats_.Reset();
+  other->accounting_stats_.Clear();
+
+  // The linear allocation area of {other} should be destroyed now.
+  DCHECK(other->top() == nullptr);
+  DCHECK(other->limit() == nullptr);
+
+  DCHECK(other->end_of_unswept_pages_ == nullptr);
 
   AccountCommitted(other->CommittedMemory());
 
   // Move over pages.
   PageIterator it(other);
   Page* p = nullptr;
   while (it.has_next()) {
     p = it.next();
     p->Unlink();
     p->set_owner(this);
@@ skipping 1358 matching lines @@
       page = Page::FromAddress(node->address());
       page->add_available_in_large_free_list(-(*node_size));
     }
   }
 
   DCHECK(IsVeryLong() || available() == SumFreeLists());
   return node;
 }
 
 
+FreeSpace* FreeList::TryRemoveMemory(intptr_t hint_size_in_bytes) {
+  base::LockGuard<base::Mutex> guard(&mutex_);
+  FreeSpace* node = nullptr;
+  int node_size = 0;
+  // Try to find a node that fits exactly.
+  node = FindNodeFor(static_cast<int>(hint_size_in_bytes), &node_size);
+  // If no node could be found get as much memory as possible.
+  if (node == nullptr) node = FindNodeIn(kHuge, &node_size);
+  if (node == nullptr) node = FindNodeIn(kLarge, &node_size);
+  if (node == nullptr) node = FindNodeIn(kMedium, &node_size);

[Michael Lippautz, 2015/10/09 12:20:13]

Remove medium and small lists?

+  if (node == nullptr) node = FindNodeIn(kSmall, &node_size);
+  if (node != nullptr) {
+    // Give back left overs that were not required by {size_in_bytes}.
+    intptr_t aligned_size = RoundUp(hint_size_in_bytes, kPointerSize);
+    intptr_t left_over = node_size - aligned_size;
+    if (left_over > 0) {
+      Free(node->address() + aligned_size, static_cast<int>(left_over));
+      node->set_size(static_cast<int>(aligned_size));
+    }
+  }
+  return node;
+}
+
+
 // Allocation on the old space free list.  If it succeeds then a new linear
 // allocation space has been set up with the top and limit of the space.  If
 // the allocation fails then NULL is returned, and the caller can perform a GC
 // or allocate a new page before retrying.
 HeapObject* FreeList::Allocate(int size_in_bytes) {
   DCHECK(0 < size_in_bytes);
   DCHECK(size_in_bytes <= kMaxBlockSize);
   DCHECK(IsAligned(size_in_bytes, kPointerSize));
   // Don't free list allocate if there is linear space available.
   DCHECK(owner_->limit() - owner_->top() < size_in_bytes);
@@ skipping 753 matching lines @@
     object->ShortPrint();
     PrintF("\n");
   }
   printf(" --------------------------------------\n");
   printf(" Marked: %x, LiveCount: %x\n", mark_size, LiveBytes());
 }
 
 #endif  // DEBUG
 }  // namespace internal
 }  // namespace v8