CPU on ubuntu goes crazy

Question

I am running ubuntu 9.10. At the sudden the CPU goes crazy and when I do top, it is used by a command called 'dd' and it is run by USER 'root'. It keeps going to for > 15 minutes.

Can you please tell what is it doing? and if I can kill it by reboot my machine?

Thank you.

Answer 1

There is usually a dd process running to copy data output by the kernel from virtual file /proc/kmsg to /var/run/syslog/kmsg, presumably so it can be kept (anything in /proc is temporary state). Under normal circumstances this process runs from boot until you shut the machine down.

If you run ps ax | grep \ dd you will see the process listed with its full command line. This command should not be consuming much resource at all so should be fine to be ignored.

Does the process show as consuming much CPU time in top? What other processes are consuming CPU time?

It would be a good idea, next time the issue occurs, to run top -n 1 and add the output of that to your question so we can see what it being reported.

Answer 2

I think the dd is cleaning up log files ... I've seen similar behaviour. You should to able to "sudo kill -9" the process, but I can't guarantee it will leave the logs in a readable state.