systemd: please stop trying to take over the world :)

[Denys Vlasenko]

On Tue, 2011-06-14 at 09:42 +0200, Lennart Poettering wrote:
> On Mon, 13.06.11 18:01, Denys Vlasenko (dvlasenk at redhat.com) wrote:
> > Maybe. It's not up to a piece of software to decide.
> > In Unix, admins should have power to decide, not programs.
> > Programs provide the means, they don't dictate policies.
> 
> Dude, systemd requires the functionality of the three modules it loads
> explicitly.

systemd requires ipv6.
And you pitch systemd to be used by embedded devices.

Do you really think all embedded devices will be happy with having such
an arbitrary requirement? Heck, I know embedded device people who remove
even ipv4!


> > > > > I think systemd is much more optimized that what existed
> > > > > previously. (what else is parallelization but optimization?) I bet with
> > > > > you that a systemd system (modulo SELinux) can be built in a way that
> > > > > uses much less resources and boot time than one built on Upstart.
> > > > 
> > > > I never used upstart. I used daemontools. I bet you can't beat *that*
> > > > on resource front. Boot time is comparable.
> > > 
> > > daemontools does not support socket activation for parallelizing
> > > execution of servers with its clients. So yes, we can beat *that*.
> > 
> > I said "you can't beat *that* on resource front". On resource front.
> > Can you beat it on resource front?
> 
> I mean, this is like comparing apples and oranges. systemd gives you an
> OS building box, daemontools nothing but a service supervisor.

Which is what I *like* about daemontools. It's Unix way to be "nothing
but" a tool for one purpose, ans serve it well.


> If you
> use daemontools you also need an init system, and boot scripts, and
> everything else. So yeah, if you compare systemd and
> daemontools+sysvinit+initscripts then, hell yeah, I can beat that.

This is not true.

daemontools can be set up in a way than most init scripts are
no longer necessary. It also achieves parallelized start.

It can also be used as an init replacement, but unlike systemd, it does
not make it a requirement.

On my home machine I use a separate init (which does only child
reaping), daemontools, and a very small set of init scripts (yes,
horror, shell scripts). It starts in about 3 seconds. The system fully
booted to text mode uses 20 megs of RAM total, all processes plus
kernel, but excluding fs cache.

You can't beat that. In fact, you are yet to reply why systemd uses
eleven megs of RAM all by itself.


daemontools don't do socket activation, therefore I'm not proposing
we use daemontools instead of systems.  IOW, I do not claim that
daemontools is a better service management tool that systemd.

I do argue that deamontools goal to provide ONLY service management
instead of being "shampoo and conditioner in one pack" is a better
approach.


> > > Hmm? systemd is an init system, so it is of course PID 1.
> > 
> > Again. *Why it has to have PID 1* to spawn and control services?
> > Can you please answer this?
> 
> Yupp, read up on Unix. Only PID 1 gets SIGCHLD for daemonized
> processes.

Why service daemon needs to receive death notifications from daemonized
processes?

-- 
vda