Reduce shutdown time

[effi]

Hi all,

I am Tung from Vietnam,
I am working on reduce shutdown time on linux, I am wondering if any one could help (Which code involved to shutdown process, is there any tool for measurement out there?)

Thank you very much in advance
Tungteng

[GNU-Fan]

You need to get familiar with the runlevels of your system.
They are controlled by a series of scripts, maybe in /etc/rc*.

The last command is the reboot command, which sends the shutdown signal to the kernel.

[effi]

Dear GNU-Fan,

Thank you very much for your reply,
I understand that (for example Ubuntu) when shutdown the scripts in /etc/rc0.d will be executed to shut down the system services, and unmount the file system, after that Kernel functions will be used (I am not sure but one of them is kernel_power_off...), kernel will also freez all the process before invoke machine_power_off()...,

I would like to trace the sequences from when SHUTDOWN SIGNAL is issued until when the machine is turn off totally and log the times it take for each step. Do you know any technique to do that?

Many thanks in advance
Effi

[GNU-Fan]

Hmm, the logging daemon is stopped right before the kernel command is issued.
After that, I don't know any standard means to record messages. You need to modify the kernel to do that, I would say. Or maybe use the output to the serial interface, which then can be recorded by another computer's telnet? Activate kernel debugger?

But didn't you say you wanted to reduce shutdown time? Once the kernel got its message, it is less than a second until machine powers off, isn't it? Why optimize there?