Fix virtual memory regression from new tcmalloc: use old kPageShift and kMaxSize w/ kNumClasses = 5…

third_party/tcmalloc/chromium/src/common.h

 // Copyright (c) 2008, Google Inc.
 // All rights reserved.
 // 
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 // 
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
@@ skipping 61 matching lines @@
   (tcmalloc::kSupportsDoublyLinkedList ? 2 : 1);
 static const size_t kLinkSize = kNumFreeListPointers * sizeof(void *);
 static const size_t kMinClassSize = 
   (kLinkSize > kAlignment ? kLinkSize : kAlignment);
 static const size_t kSkippedClasses = (kAlignment < kMinClassSize ? 1 : 0);
 
 #if defined(TCMALLOC_LARGE_PAGES)
 static const size_t kPageShift  = 15;
 static const size_t kNumClasses = 78 - kSkippedClasses;
 #else
-static const size_t kPageShift  = 13;
-static const size_t kNumClasses = 86 - kSkippedClasses;
+// Original TCMalloc code used kPageShift == 13.  In Chromium, we changed
+// this to 12 (as was done in prior versions of TCMalloc).
+static const size_t kPageShift  = 12;
+static const size_t kNumClasses = 54 - kSkippedClasses;
 #endif
 static const size_t kMaxThreadCacheSize = 4 << 20;
 
 static const size_t kPageSize   = 1 << kPageShift;
-// TODO(dmikurube): We Chromium may want to tune this kMaxSize.
-static const size_t kMaxSize    = 256 * 1024;
+// Original TCMalloc code used kMaxSize == 256 * 1024.  In Chromium, we
+// changed this to 32K, and represent it in terms of page size (as was done
+// in prior versions of TCMalloc).
+static const size_t kMaxSize    = 8u * kPageSize;
 // For all span-lengths < kMaxPages we keep an exact-size list.
 static const size_t kMaxPages = 1 << (20 - kPageShift);
 
 // Default bound on the total amount of thread caches.
 #ifdef TCMALLOC_SMALL_BUT_SLOW
 // Make the overall thread cache no bigger than that of a single thread
 // for the small memory footprint case.
 static const size_t kDefaultOverallThreadCacheSize = kMaxThreadCacheSize;
 #else
 static const size_t kDefaultOverallThreadCacheSize = 8u * kMaxThreadCacheSize;
@@ skipping 154 matching lines @@
 static const int kMaxStackDepth = 31;
 struct StackTrace {
   uintptr_t size;          // Size of object
   uintptr_t depth;         // Number of PC values stored in array below
   void*     stack[kMaxStackDepth];
 };
 
 }  // namespace tcmalloc
 
 #endif  // TCMALLOC_COMMON_H_