用来获取linux的CPU、MEM、交换空间，硬盘使用率等性能指标- Linux used to obtain the CPU, MEM, swap space, hard disk usage and other performance indicators

reports physical memory usage, taking shared memory pages into account. Unshared memory is reported as the USS (Unique Set Size). Shared memory is divided evenly among the processes sharing that memory. The unshared memory (USS) plus a process