OOM score for every process

Question

In response to this.

Take a look to the questions about configuring the OOM killer. For example: https://unix.stackexchange.com/q/153585/21101

I am looking for what process would be killed first in the case of low memory.

Is there a way to see the OOM score for every process instead of each individually?

Answer 1

At its simplest, you could just do

cat /proc/*/oom_score

If you want more information - such as the PIDs and command string as well - then maybe a simple loop like

while read -r pid comm; do 
  printf '%d\t%d\t%s\n' "$pid" "$(cat /proc/$pid/oom_score)" "$comm"
done < <(ps -e -o pid= -o comm=)

Answer 2

Here is a long one-liner which adds the OOM score of each process to the output of "ps":

export oom_prop="oom_score"
ps axfuww | perl -pe 's/^(USER\s+PID)/sprintf("%s %s", $1, uc($ENV{"oom_prop"}))/e' | perl -MFile::Slurp -pe 's~^(\S+\s+)(\d+)(\s+)~sprintf("%s%s%s%*s  ", $1, $2, $3, length($ENV{"oom_prop"}) - 1, read_file("/proc/$2/$ENV{\"oom_prop\"}", {err_mode => "quiet", chomp => 1}))~e' | less -S

The "ps" output looks like this:

USER         PID OOM_SCORE %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root           1         0  0.0  0.2 169612 13128 ?        Ss   Sep27   0:08 /sbin/init
root         275       508  0.0  2.2 186404 114428 ?       S<s  Sep27   0:06 /lib/systemd/systemd-journald
root         339         0  0.0  0.1  24260  6880 ?        Ss   Sep27   0:09 /lib/systemd/systemd-udevd
root         568       666  0.0  0.1 241940  8612 ?        Ssl  Sep27   0:16 /usr/lib/accountsservice/accounts-daemon
root         572       666  0.0  0.0   2540   768 ?        Ss   Sep27   0:05 /usr/sbin/acpid
...

You can control which OOM property to monitor by specifying "oom_score" or "oom_score_adj" in the export oom_prop initial command.

You also need the File::Slurp Perl module. It is a popular module and you should be able to install it either using the packaging system of your OS, or via CPAN.