轉：https://blog.csdn.net/mr_leehy/article/details/76419363
使用w命令查看用戶登錄信息時，會顯示到PCPU與JCPU，這個概念是什么意思呢？
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，得到的解釋是
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.
中文可以這樣理解：JCPU指的是與該tty終端連接的所由進程占用的時間，不包括過去的后台作業時間；PCPU 指的是當前進程(即w項中顯示的)所占用的時間。