On Fri, Jan 21, 2011 at 3:07 AM, Heiko Baums <lists@baums-on-web.de> wrote:
3. Parallel booting (staring several daemons parallel at boot time) can make booting significantly slower particularly on older and slower systems. Serial is quite often a lot faster than parallel. The harddisk can only make one read or write access at a time. So there's hardly benefit of starting daemons (reading them from the harddisk) parallel. Btw., such a parallelization of starting daemons is already possible with Arch's and Gentoo's sysv init system. So systemd is not needed for that.
Parallel *is* faster because the kernel can put all those reads into an optimal order. Also, the obvious multiprocessing. Arch's init system is completely ignorant of dependencies.
5. In the same article I read that systemd binds itself to port 80 instead of starting apache at boottime and starts apache only if a request to port 80 comes in. This is not the task of an init system, and I have slight security concerns about that. If I tell the init system that I want apache being started then I want to have apache started at boottime or when I say so and not when systemd thinks it is needed. And this way systemd first needs to unbind itself from port 80 and then start apache and bind it to port 80. So if I open port 80 in my firewall this port is open without a software being bound to it, even if it's only a millisecond.
This does not happen. This particular feature of systemd requires a patched apache, so systemd can hand the port over to the newly started server.