[systemd-devel] experiments with 'minimal build'

[Mantas Mikulėnas]

On Wed, Mar 18, 2015 at 9:07 AM, Alison Chaiken <alison at she-devel.com>
wrote:

> After reading about the 'minimal build' on the systemd wiki, I decided
> to experiment.
>
> 0. WIth basically all options turned on, in a Fedora 21 Qemu, systemd
> used about 300 MB of memory according to 'sudo memstat -p 1'.
>
> 1. With ./configure --disable-gtk-doc --disable-seccomp [&c.]
>
> In this case, 'memstat -p 1' says systemd uses about 119 MB of memory.
>

memstat only reports *virtual* memory size, including mapped files and
other things that only need the address space, but *not necessarily* occupy
physical RAM or any other shared resources. Remember that each process has
its own address space, it's not really a sparse resource... (So tools like
`journalctl` might even show up as "using" more total memory than the
system actually *has*.)

So the number is mostly meaningless if you're trying to determine actual
resource usage. The "RSS" column in `ps u 1`, `pmap -x -p 1` or in htop
describes it a bit better. Generally systemd-pid1 will be ~5 MB; journald
tends to be the largest – it's 12 MB on my system [though in previous
versions it used to grow to 50 or even 100 MB].

-- 
Mantas Mikulėnas <grawity at gmail.com>
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