Reland: Fix logic for incremental marking steps on tenured allocation

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/v8.h"
 
 #include "src/base/bits.h"
 #include "src/base/platform/platform.h"
 #include "src/full-codegen.h"
 #include "src/heap/mark-compact.h"
@@ skipping 2182 matching lines @@
   free_bytes += huge_list_.Concatenate(free_list->huge_list());
   return free_bytes;
 }
 
 
 void FreeList::Reset() {
   small_list_.Reset();
   medium_list_.Reset();
   large_list_.Reset();
   huge_list_.Reset();
+  unreported_allocation_ = 0;
 }
 
 
 int FreeList::Free(Address start, int size_in_bytes) {
   if (size_in_bytes == 0) return 0;
 
   heap_->CreateFillerObjectAt(start, size_in_bytes);
 
   Page* page = Page::FromAddress(start);
 
@@ skipping 127 matching lines @@
       page = Page::FromAddress(node->address());
       page->add_available_in_large_free_list(-(*node_size));
     }
   }
 
   DCHECK(IsVeryLong() || available() == SumFreeLists());
   return node;
 }
 
 
+void PagedSpace::SetTopAndLimit(Address top, Address limit) {
+  DCHECK(top == limit ||
+         Page::FromAddress(top) == Page::FromAddress(limit - 1));
+  MemoryChunk::UpdateHighWaterMark(allocation_info_.top());
+  allocation_info_.set_top(top);
+  allocation_info_.set_limit(limit);
+}
+
+
 // 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);
 
   int old_linear_size = static_cast<int>(owner_->limit() - owner_->top());
   // Mark the old linear allocation area with a free space map so it can be
   // skipped when scanning the heap.  This also puts it back in the free list
   // if it is big enough.
   owner_->Free(owner_->top(), old_linear_size);
 
-  owner_->heap()->incremental_marking()->OldSpaceStep(size_in_bytes -
-                                                      old_linear_size);
-
   int new_node_size = 0;
   FreeSpace* new_node = FindNodeFor(size_in_bytes, &new_node_size);
   if (new_node == NULL) {
     owner_->SetTopAndLimit(NULL, NULL);
     return NULL;
   }
 
   int bytes_left = new_node_size - size_in_bytes;
   DCHECK(bytes_left >= 0);
 
 #ifdef DEBUG
   for (int i = 0; i < size_in_bytes / kPointerSize; i++) {
     reinterpret_cast<Object**>(new_node->address())[i] =
         Smi::FromInt(kCodeZapValue);
   }
 #endif
 
   // The old-space-step might have finished sweeping and restarted marking.
   // Verify that it did not turn the page of the new node into an evacuation
   // candidate.
   DCHECK(!MarkCompactCollector::IsOnEvacuationCandidate(new_node));
 
-  const int kThreshold = IncrementalMarking::kAllocatedThreshold;
+  // An old-space step will mark more data per byte allocated, because old space
+  // allocation is more serious.  We don't want the pause to be bigger, so we
+  // do marking after a smaller amount of allocation.
+  const int kThreshold = IncrementalMarking::kAllocatedThreshold *
+                         IncrementalMarking::kOldSpaceAllocationMarkingFactor;
 
   // Memory in the linear allocation area is counted as allocated.  We may free
   // a little of this again immediately - see below.
   owner_->Allocate(new_node_size);
 
+  unreported_allocation_ += new_node_size;
+
   if (owner_->heap()->inline_allocation_disabled()) {
     // Keep the linear allocation area empty if requested to do so, just
     // return area back to the free list instead.
     owner_->Free(new_node->address() + size_in_bytes, bytes_left);
     DCHECK(owner_->top() == NULL && owner_->limit() == NULL);
   } else if (bytes_left > kThreshold &&
-             owner_->heap()->incremental_marking()->IsMarkingIncomplete() &&
-             FLAG_incremental_marking_steps) {
+             owner_->heap()->incremental_marking()->CanDoSteps()) {
     int linear_size = owner_->RoundSizeDownToObjectAlignment(kThreshold);
+
     // We don't want to give too large linear areas to the allocator while
     // incremental marking is going on, because we won't check again whether
     // we want to do another increment until the linear area is used up.
     owner_->Free(new_node->address() + size_in_bytes + linear_size,
                  new_node_size - size_in_bytes - linear_size);
     owner_->SetTopAndLimit(new_node->address() + size_in_bytes,
                            new_node->address() + size_in_bytes + linear_size);
-  } else if (bytes_left > 0) {
-    // Normally we give the rest of the node to the allocator as its new
-    // linear allocation area.
-    owner_->SetTopAndLimit(new_node->address() + size_in_bytes,
-                           new_node->address() + new_node_size);
+    // It is important that we are done updating top and limit before we call
+    // this.

[Hannes Payer (out of office), 2015/04/22 14:06:21]

Can you say way in the comment to make it clear?

[Erik Corry Chromium.org, 2015/06/29 14:45:30]

Done.

+    owner_->heap()->incremental_marking()->OldSpaceStep(size_in_bytes +
+                                                        linear_size);
+    unreported_allocation_ = 0;
   } else {

[Hannes Payer (out of office), 2015/04/22 14:06:21]

Please add the same comment from above also here.

[Erik Corry Chromium.org, 2015/06/29 14:45:30]

The comment is there, just before the call to OldSpaceStep, below.

-    // TODO(gc) Try not freeing linear allocation region when bytes_left
-    // are zero.
-    owner_->SetTopAndLimit(NULL, NULL);
+    if (bytes_left > 0) {
+      // Normally we give the rest of the node to the allocator as its new
+      // linear allocation area.
+      owner_->SetTopAndLimit(new_node->address() + size_in_bytes,
+                             new_node->address() + new_node_size);
+    } else {
+      // TODO(gc) Try not freeing linear allocation region when bytes_left
+      // are zero.
+      owner_->SetTopAndLimit(NULL, NULL);
+    }
+    if (unreported_allocation_ > kThreshold) {
+      // This may start the incremental marker, or do a little work if it's
+      // already started. It is important that we are finished updating top
+      // and limit before we call this.
+      owner_->heap()->incremental_marking()->OldSpaceStep(
+          Min(kThreshold, unreported_allocation_));
+      unreported_allocation_ = 0;
+    }
   }
 
   return new_node;
 }
 
 
 intptr_t FreeList::EvictFreeListItems(Page* p) {
   intptr_t sum = huge_list_.EvictFreeListItemsInList(p);
   p->set_available_in_huge_free_list(0);
 
@@ skipping 466 matching lines @@
   MSAN_ALLOCATED_UNINITIALIZED_MEMORY(object->address(), object_size);
 
   if (Heap::ShouldZapGarbage()) {
     // Make the object consistent so the heap can be verified in OldSpaceStep.
     // We only need to do this in debug builds or if verify_heap is on.
     reinterpret_cast<Object**>(object->address())[0] =
         heap()->fixed_array_map();
     reinterpret_cast<Object**>(object->address())[1] = Smi::FromInt(0);
   }
 
-  heap()->incremental_marking()->OldSpaceStep(object_size);
+  // We would like to tell the incremental marker to do a lot of work, since
+  // we just made a large allocation in old space, but that might cause a huge
+  // pause. Underreporting here may cause the marker to speed up because it
+  // will perceive that it is not keeping up with allocation. Although this
+  // causes some big incremental marking steps they are not as big as this one
+  // might have been. In testing, a very large pause was divided up into about
+  // 12 parts.
+  const int kThreshold = IncrementalMarking::kAllocatedThreshold *
+                         IncrementalMarking::kOldSpaceAllocationMarkingFactor;
+  heap()->incremental_marking()->OldSpaceStep(kThreshold);
   return object;
 }
 
 
 size_t LargeObjectSpace::CommittedPhysicalMemory() {
   if (!base::VirtualMemory::HasLazyCommits()) return CommittedMemory();
   size_t size = 0;
   LargePage* current = first_page_;
   while (current != NULL) {
     size += current->CommittedPhysicalMemory();
@@ skipping 202 matching lines @@
     object->ShortPrint();
     PrintF("\n");
   }
   printf(" --------------------------------------\n");
   printf(" Marked: %x, LiveCount: %x\n", mark_size, LiveBytes());
 }
 
 #endif  // DEBUG
 }
 }  // namespace v8::internal