转：https://blog.csdn.net/mr_leehy/article/details/76419363
使用w命令查看用户登录信息时，会显示到PCPU与JCPU，这个概念是什么意思呢？
JCPU - the CPU time used by all processes and their children on that terminal (in minutes:seconds)
PCPU - the CPU time used by the currently active processes (in minutes:seconds)
使用：man w，得到的解释是
The JCPU time is the time used by all processes attached to the tty. It does not include past background jobs, but does include currently running background jobs.
The PCPU time is the time used by the current process.
中文可以这样理解：JCPU指的是与该tty终端连接的所由进程占用的时间，不包括过去的后台作业时间；PCPU 指的是当前进程(即w项中显示的)所占用的时间。