how to determine the runtime and start time of a Linux process
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Yesterday, I needed to determine the runtime of a Linux process for a monitoring script. Cos the format for start_time of the ps command may change if the process was not started in the same year, I decided to take the neccessary informations from the /proc/<PID>/stat file.
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Yesterday, I needed to determine the runtime of a Linux process for a monitoring script. Cos the format for start_time of the ps command may change if the process was not started in the same year, I decided to take the neccessary informations from the /proc/<PID>/stat file.
In this file the process start time since boot is defined at the twenty-second field, expressed in Jiffies – the scale unit of the system timer. (One Jiffie is one tick of the system timer).
To convert Jiffies to seconds I just have to divide the number of Jiffies by the frequency (hertz) of the system timer, which is defined in the Linux Kernel header file include/asm-generic/param.h. The frequency may differ between Linux kernel versions and hardware platform! On my Linux systems the frequency is 100 HZ. Full Story |
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