[heap] Switch to 500k pages

src/heap/spaces.cc

Index: src/heap/spaces.cc
diff --git a/src/heap/spaces.cc b/src/heap/spaces.cc
index b31aaf3998fd98a370b3a329dcfb992c12f9e112..18d8e228fbbee6659e950ecd8048a479f575b55e 100644
--- a/src/heap/spaces.cc
+++ b/src/heap/spaces.cc
@@ -1213,17 +1213,39 @@ Object* PagedSpace::FindObject(Address addr) {
   return Smi::FromInt(0);
 }
 
-bool PagedSpace::Expand() {
-  int size = AreaSize();
-  if (snapshotable() && !HasPages()) {
-    size = Snapshot::SizeOfFirstPage(heap()->isolate(), identity());
+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();
+}
 
-  if (!heap()->CanExpandOldGeneration(size)) return false;
+bool PagedSpace::Expand() {
+  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.