public static int overhead() {
    // TODO: revisit this code. If we move to per-region cds then this can no longer be static.
    // TODO: This method also does not work well with the way off heap is determined using the
    // cache.

    if (STORE_ALL_VALUE_FORMS) {
      return StoreAllCachedDeserializable.MEM_OVERHEAD;
    } else if (PREFER_DESERIALIZED) {
      // PDX: this may instead be PreferBytesCachedDeserializable.MEM_OVERHEAD
      return VMCachedDeserializable.MEM_OVERHEAD;
    } else {
      return PreferBytesCachedDeserializable.MEM_OVERHEAD;
    }

  }
Return the heap overhead in bytes for each CachedDeserializable instance.
geode-core/src/main/java/org/apache/geode/internal/cache/CachedDeserializableFactory.java