[heap] Switch to 500k pages

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/base/platform/semaphore.h"
 #include "src/full-codegen/full-codegen.h"
@@ skipping 1195 matching lines @@
   for (HeapObject* obj = it.Next(); obj != NULL; obj = it.Next()) {
     Address cur = obj->address();
     Address next = cur + obj->Size();
     if ((cur <= addr) && (addr < next)) return obj;
   }
 
   UNREACHABLE();
   return Smi::FromInt(0);
 }
 
+int PagedSpace::AreaSizeDuringDeserialization() {
+  // Try to keep the memory as compact as possible for a snapshot. This way the
+  // heap stays small for small/empty scripts.
+  DCHECK(snapshotable());
+  DCHECK(!heap()->deserialization_complete());
+  uint32_t snapshot_requires =
+      Snapshot::SizeOfSnapshot(heap()->isolate(), identity());
+  if (snapshot_requires > 0) {

[Hannes Payer (out of office), 2016/08/08 16:25:02]

I think this if case should be a DCHECK and the else default should not exist,
i.e. the function should only be called if we are deserializing a snapshot.

[Michael Lippautz, 2016/08/09 11:30:25]

Obsolete.

+    // Count how much we have served already.
+    size_t memory_served = 0;
+    for (Page* page : *this) {
+      memory_served += page->area_size();

[Hannes Payer (out of office), 2016/08/08 16:25:02]

size of actual objects would be more precise here.

[Michael Lippautz, 2016/08/09 11:30:25]

Obsolete.

+    }
+    size_t needed = static_cast<size_t>(snapshot_requires) - memory_served;
+    const int area_size = MemoryAllocator::PageAreaSize(identity());

[Hannes Payer (out of office), 2016/08/08 16:25:02]

Just call AreaSize() here.

[Michael Lippautz, 2016/08/09 11:30:25]

Obsolete.

+    if (needed >= static_cast<size_t>(area_size)) return area_size;
+    // Less than a page of memory needed. We need to allocate at least
+    // kMaxRegularHeapObjectSize of space.
+    if (needed < Page::kMaxRegularHeapObjectSize)
+      return Page::kMaxRegularHeapObjectSize;
+    return static_cast<int>(needed);

[Hannes Payer (out of office), 2016/08/08 16:25:02]

Maybe we should do a different approach here:
How about just allocated as much memory as needed and then shrink the pages
after deserialization?

[Michael Lippautz, 2016/08/09 11:30:25]

Done.

+  }
+  return AreaSize();
+}
+
 bool PagedSpace::Expand() {
-  int size = AreaSize();
-  if (snapshotable() && !HasPages()) {
-    size = Snapshot::SizeOfFirstPage(heap()->isolate(), identity());
-  }
+  int size = heap()->deserialization_complete()
+                 ? AreaSize()
+                 : AreaSizeDuringDeserialization();
 
   if (!heap()->CanExpandOldGeneration(size)) return false;
-
   Page* p = heap()->memory_allocator()->AllocatePage(size, this, executable());
   if (p == nullptr) return false;
-
   AccountCommitted(static_cast<intptr_t>(p->size()));
 
   // Pages created during bootstrapping may contain immortal immovable objects.
   if (!heap()->deserialization_complete()) p->MarkNeverEvacuate();
 
   DCHECK(Capacity() <= heap()->MaxOldGenerationSize());
 
   p->InsertAfter(anchor_.prev_page());
 
   return true;
@@ skipping 1895 matching lines @@
     object->ShortPrint();
     PrintF("\n");
   }
   printf(" --------------------------------------\n");
   printf(" Marked: %x, LiveCount: %x\n", mark_size, LiveBytes());
 }
 
 #endif  // DEBUG
 }  // namespace internal
 }  // namespace v8