该消息只能用于与同步操作。

The message can be used only with <em>synchronous</em> <em>operation</em>s.

对于真正的同步操作，cp 命令花费的时间太长，效率很低。

It is comparatively too time-consuming and inefficient for a true sync operation.

通常，动态分配需要为每次分配增加一些空间开销来保簿记信息，还有同步操作以保护来自不同线程的并发分配。

Normally, dynamic allocation imposes a size overhead for each allocation to store bookkeeping information and a synchronization to protected concurrent allocation from different threads.