Reduce minimum memory use on 64 bit to one page per semispace.

Review URL: http://codereview.chromium.org/8774045

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10144 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/heap.cc

@@ -80,7 +80,7 @@ Heap::Heap()
 #endif
       reserved_semispace_size_(8 * Max(LUMP_OF_MEMORY, Page::kPageSize)),
       max_semispace_size_(8 * Max(LUMP_OF_MEMORY, Page::kPageSize)),
-      initial_semispace_size_(Max(LUMP_OF_MEMORY, Page::kPageSize)),
+      initial_semispace_size_(Page::kPageSize),
       max_old_generation_size_(700ul * LUMP_OF_MEMORY),
       max_executable_size_(128l * LUMP_OF_MEMORY),
 

test/cctest/test-mark-compact.cc

@@ -528,7 +528,7 @@ TEST(BootUpMemoryUse) {
   if (initial_memory >= 0) {
     InitializeVM();
     intptr_t booted_memory = MemoryInUse();
-    CHECK_LE(booted_memory - initial_memory, 18 * 1024 * 1024);
+    CHECK_LE(booted_memory - initial_memory, 16 * 1024 * 1024);
   }
 }