Remove sequential sweeping mode and perform lazy sweeping when no sweeper threads are active.

src/spaces.h

 // 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.
 
 #ifndef V8_SPACES_H_
 #define V8_SPACES_H_
 
 #include "src/allocation.h"
 #include "src/base/atomicops.h"
 #include "src/base/platform/mutex.h"
@@ skipping 1601 matching lines @@
   }
 
   // Place a node on the free list.  The block of size 'size_in_bytes'
   // starting at 'start' is placed on the free list.  The return value is the
   // number of bytes that have been lost due to internal fragmentation by
   // freeing the block.  Bookkeeping information will be written to the block,
   // i.e., its contents will be destroyed.  The start address should be word
   // aligned, and the size should be a non-zero multiple of the word size.
   int Free(Address start, int size_in_bytes);
 
+  // This method returns how much memory can be allocated after freeing
+  // maximum_freed memory.
+  int GuaranteedAllocatable(int maximum_freed) {
+    if (maximum_freed < kSmallListMin) {
+      return 0;
+    } else if (maximum_freed <= kSmallListMax) {
+      return kSmallAllocationMax;
+    } else if (maximum_freed <= kMediumListMax) {
+      return kMediumAllocationMax;
+    } else if (maximum_freed <= kLargeListMax) {
+      return kLargeAllocationMax;
+    }
+    return maximum_freed;
+  }
+
   // Allocate a block of size 'size_in_bytes' from the free list.  The block
   // is unitialized.  A failure is returned if no block is available.  The
   // number of bytes lost to fragmentation is returned in the output parameter
   // 'wasted_bytes'.  The size should be a non-zero multiple of the word size.
   MUST_USE_RESULT HeapObject* Allocate(int size_in_bytes);
 
   bool IsEmpty() {
     return small_list_.IsEmpty() && medium_list_.IsEmpty() &&
            large_list_.IsEmpty() && huge_list_.IsEmpty();
   }
@@ skipping 266 matching lines @@
 
   // Report code object related statistics
   void CollectCodeStatistics();
   static void ReportCodeStatistics(Isolate* isolate);
   static void ResetCodeStatistics(Isolate* isolate);
 #endif
 
   bool is_iterable() { return is_iterable_; }
   void set_is_iterable(bool b) { is_iterable_ = b; }
 
-  bool is_swept_concurrently() { return is_swept_concurrently_; }
-  void set_is_swept_concurrently(bool b) { is_swept_concurrently_ = b; }
-
   // Evacuation candidates are swept by evacuator.  Needs to return a valid
   // result before _and_ after evacuation has finished.
   static bool ShouldBeSweptBySweeperThreads(Page* p) {
     return !p->IsEvacuationCandidate() &&
            !p->IsFlagSet(Page::RESCAN_ON_EVACUATION) &&
            !p->WasSweptPrecisely();
   }
 
   void IncrementUnsweptFreeBytes(intptr_t by) {
     unswept_free_bytes_ += by;
@@ skipping 64 matching lines @@
 
   // The space's free list.
   FreeList free_list_;
 
   // Normal allocation information.
   AllocationInfo allocation_info_;
 
   // This space was swept precisely, hence it is iterable.
   bool is_iterable_;
 
-  // This space is currently swept by sweeper threads.
-  bool is_swept_concurrently_;
-
   // The number of free bytes which could be reclaimed by advancing the
   // concurrent sweeper threads.  This is only an estimation because concurrent
   // sweeping is done conservatively.
   intptr_t unswept_free_bytes_;
 
   // The sweeper threads iterate over the list of pointer and data space pages
   // and sweep these pages concurrently. They will stop sweeping after the
   // end_of_unswept_pages_ page.
   Page* end_of_unswept_pages_;
 
   // Expands the space by allocating a fixed number of pages. Returns false if
   // it cannot allocate requested number of pages from OS, or if the hard heap
   // size limit has been hit.
   bool Expand();
 
   // Generic fast case allocation function that tries linear allocation at the
   // address denoted by top in allocation_info_.
   inline HeapObject* AllocateLinearly(int size_in_bytes);
 
   // If sweeping is still in progress try to sweep unswept pages. If that is
   // not successful, wait for the sweeper threads and re-try free-list
   // allocation.
-  MUST_USE_RESULT HeapObject* EnsureSweepingProgress(int size_in_bytes);
+  MUST_USE_RESULT HeapObject* WaitForSweeperThreadsAndRetryAllocation(
+      int size_in_bytes);
 
   // Slow path of AllocateRaw.  This function is space-dependent.
   MUST_USE_RESULT HeapObject* SlowAllocateRaw(int size_in_bytes);
 
   friend class PageIterator;
   friend class MarkCompactCollector;
 };
 
 
 class NumberAndSizeInfo BASE_EMBEDDED {
@@ skipping 985 matching lines @@
   }
   // Must be small, since an iteration is used for lookup.
   static const int kMaxComments = 64;
 };
 #endif
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_SPACES_H_