Submission type

• Request for enhancement (RFE)

systemd version the issue has been seen with

code seen in master

Used distribution

Fedora

RFE

I've been overloading my RAM a bit lately.

StackOverflow has a one-liner to print per-process swap usage. I notice that (sd-pam) can end up with more swap accounted than the parent systemd currently has. Like, almost 2MB!

This is basically all going to be dead memory as far as (sd-pam) is concerned. I think it's got to be copy-on-write pages from PID 1.

If the parent is also modifying memory while the child runs, the child will be hosting copies of all the modified memory (copy-on-write). Often the child is performing a sub-task and only uses a subset of that data.

It's possible for it to be significant with a larger parent process and longer-running child process.

$ (echo "COMM PID SWAP"; for file in /proc/*/status ; do awk '/^Pid|VmSwap|Name/{printf $2 " " $3}END{ print ""}' $file; done | grep kB | grep -wv "0 kB" | sort -k 3 -n -r) | column -t | grep -E 'sys|[(]'
systemd-udevd    586    4436   kB
(sd-pam)         2215   3900   kB
(sd-pam)         1023   3896   kB
(sd-pam)         17506  2488   kB
systemd          1      2260   kB
systemd-logind   840    960    kB
systemd          1007   748    kB
systemd-journal  560    656    kB
systemd          2210   652    kB