The reason for this is that memory is a "real" (or let's say non-virtual) entity, the statistics about memory consumed is maintained by the kernel and is always current.
原因在于，内存是“真实的”(或者说非虚拟的)实体，关于内存消耗的统计数据由内核维护，总是最新的。
2
Softswitch is a function entity. It provides call control and access control of real time service. It is the kernel of NGN's call and control.