Linux：/ proc / [pid] / stat中的starttime字段使用HZ（jiffies）或USER_HZ（_SC_CLK_TCK）

I wan't to measure the executing duration of a process outside this process on Linux. I found /proc/[pid]/state has a field named starttime which described to be "The time in jiffies the process started after system boot" on man page. I wan't to measure the executing duration of a