Try fixing virtual memory regression from new tcmalloc: use old kPageShift and kMaxSize w/ totally …

third_party/tcmalloc/chromium/src/common.cc

Index: third_party/tcmalloc/chromium/src/common.cc
diff --git a/third_party/tcmalloc/chromium/src/common.cc b/third_party/tcmalloc/chromium/src/common.cc
index dd175f223692a5adb37048140b30422bae79fe40..30eaa2e85e545f7afdc6857b8c67f6b029dd1df9 100644
--- a/third_party/tcmalloc/chromium/src/common.cc
+++ b/third_party/tcmalloc/chromium/src/common.cc
@@ -58,9 +58,9 @@ static inline int LgFloor(size_t n) {
 
 int AlignmentForSize(size_t size) {
   int alignment = kAlignment;
-  if (size > kMaxSize) {
-    // Cap alignment at kPageSize for large sizes.
-    alignment = kPageSize;
+  if (size >= 2048) {
+    // Cap alignment at 256 for large sizes.
+    alignment = 256;
   } else if (size >= 128) {
     // Space wasted due to alignment is at most 1/8, i.e., 12.5%.
     alignment = (1 << LgFloor(size)) / 8;
@@ -69,10 +69,6 @@ int AlignmentForSize(size_t size) {
     // requirements for some SSE types.
     alignment = 16;
   }
-  // Maximum alignment allowed is page size alignment.
-  if (alignment > kPageSize) {
-    alignment = kPageSize;
-  }
   CHECK_CONDITION(size < 16 || alignment >= 16);
   CHECK_CONDITION((alignment & (alignment - 1)) == 0);
   return alignment;
@@ -115,23 +111,22 @@ void SizeMap::Init() {
   int sc = 1;   // Next size class to assign
   int alignment = kAlignment;
   CHECK_CONDITION(kAlignment <= 16);
+  int last_lg = -1;
   for (size_t size = kMinClassSize; size <= kMaxSize; size += alignment) {
-    alignment = AlignmentForSize(size);
+    int lg = LgFloor(size);
+    if (lg > last_lg) {
+      // Increase alignment every so often to reduce number of size classes.
+      alignment = AlignmentForSize(size);
+      last_lg = lg;
+    }
     CHECK_CONDITION((size % alignment) == 0);
 
-    int blocks_to_move = NumMoveSize(size) / 4;
-    size_t psize = 0;
-    do {
+    // Allocate enough pages so leftover is less than 1/8 of total.
+    // This bounds wasted space to at most 12.5%.
+    size_t psize = kPageSize;
+    while ((psize % size) > (psize >> 3)) {
       psize += kPageSize;
-      // Allocate enough pages so leftover is less than 1/8 of total.
-      // This bounds wasted space to at most 12.5%.
-      while ((psize % size) > (psize >> 3)) {
-        psize += kPageSize;
-      }
-      // Continue to add pages until there are at least as many objects in
-      // the span as are needed when moving objects from the central
-      // freelists and spans to the thread caches.
-    } while ((psize / size) < (blocks_to_move));
+    }
     const size_t my_pages = psize >> kPageShift;
 
     if (sc > 1 && my_pages == class_to_pages_[sc-1]) {