Can't change nice value on processes I find when running top?

shanebagel · 06-01-2022, 05:47 PM

I continue to get "No such file or directory" when running nice on the commands I receive from top.

For example:
I run top and see a bunch of processes I'd like to try changing nice values on and bash can't seem to locate the file?
[root@localhost ~]# nice -n 5 systemd
nice: systemd: No such file or directory
[root@localhost ~]# nice -n 5 kdevtmpfs
nice: kdevtmpfs: No such file or directory
[root@localhost ~]# nice -n 5 khungtaskd
nice: khungtaskd: No such file or directory
[root@localhost ~]# nice -n 5 watchdog/0
nice: watchdog/0: No such file or directory

shanebagel · 06-01-2022, 05:54 PM

Nevermind, I figured this out! They're kernel modules right?

suramya · 06-01-2022, 05:58 PM

nice is used to run commands with a modified priority level, so that a process can have a higher priority or a lower priority than the default value.
It is used to the set the value when the program is started. If the program is already running you need to use renice to change the priority.

Check out: https://www.tecmint.com/set-linux-pr...nice-commands/ for examples of both commands.

ondoho · 06-04-2022, 01:06 AM

Quote:

Originally Posted by shanebagel

Nevermind, I figured this out! They're kernel modules right?

I don't think so:

Code:

$> ps aux | grep -E '^USER|systemd|kdevtmpfs|khungtaskd|watchdog/0'
USER         PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root          35  0.0  0.0      0     0 ?        S    May28   0:00 [kdevtmpfs]
root          40  0.0  0.0      0     0 ?        S    May28   0:00 [khungtaskd]
root         245  0.0  1.6 539764 58388 ?        Ss   May28   7:07 /lib/systemd/systemd-journald
root         285  0.0  0.1  21660  4188 ?        Ss   May28   0:02 /lib/systemd/systemd-udevd
systemd+     463  0.0  0.3  24036 11356 ?        Ss   May28   0:29 /lib/systemd/systemd-resolved
message+     470  0.0  0.1   7932  4224 ?        Ss   May28   1:08 /usr/bin/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activation --syslog-only
root         479  0.0  0.1  13592  6604 ?        Ss   May28   0:34 /lib/systemd/systemd-logind
root         642  0.0  0.1  13112  5152 ?        Ss   May28   0:00 systemd-tty-ask-password-agent --wall
....snip....

These all have PIDs, so they're processes.
Why nice doesn't work on them I do not know, but - what are you really trying to achieve here? Messing around with the systemd process is a very bad idea.