[blfs-support] Systemd's journal (was Re: Latest news in GNOME world)

Matt Burgess matthew at linuxfromscratch.org
Mon Nov 12 12:54:20 PST 2012


On Mon, 2012-11-12 at 11:56 -0600, Bruce Dubbs wrote:

> What advantages does systemd give?
> 
> Binary logs?  That's a little difficult to work with if Xorg isn't 
> working.  How do you grep a binary log?

I was going to say 'me too' to all of your post, Bruce, but then, in
trying to find the list of 18(!) guides on how to use the various
components of systemd came across
http://0pointer.de/blog/projects/journalctl.html which describes how to
access the binary logs.  The features it provides all seem pretty neat
and all accessible from the command line.  So, that's one less thing for
me to hold against it.

> cgroups?  What advantages does that give to a single user workstation? 
> A dedicated LAMP server?  Factor those systems out and how many systems 
> are left?

http://0pointer.de/blog/projects/resources.html details systemd's
usage/control of cgroups.  It appears to be the per-service equivalent
of the per-process utilities such as 'nice' and 'ionice'.  e.g. If you
want your MySQL service (which consists of, for example, 5 worker
threads) to use a greater share of your CPU than the 25 child processes
of the 'httpd' service, you can use systemd's resource management to do
that.

I understand the concept, but not really the usefulness of it all.  If
you're that tightly resource constrained, why wouldn't you just shift
your MySQL service to a dedicated box or shove more/faster CPUs into
your existing kit?

> Fast bootup?  I've got my system down to less than 8 seconds.  Shutdown 
> is about 4 seconds.  The reason for commercial system boot problems is 
> because they want one system to boot any hardware.  That means hundreds 
> (thousands?) of modules.  Note that boot time is also a function of 
> hardware.  On a virtual system like kvm, boot time from grub to login 
> prompt is about 2 seconds!

Ha, fast bootup?  Fedora 17 takes a ridiculous amount of time to boot on
this laptop.  Next time I reboot it, I'll get an accurate timing of it,
but gut feel says that it's over 2 minutes before I get to the GDM login
prompt.

> When I complained once about systemd on a list that the devs read, they 
> asked why there was a problem understanding systemd.  After all there 
> was 100 pages of documentation.  I replied that that problem was that 
> 100 pages of documentation were needed.

Yeah, there's 18 'systemd for Administrators' articles so far in the
series, although I must admit that the 2 I've scanned over this evening
do read quite well.  Maybe if systemd wasn't such a 'dumping ground' of
(on the surface) unrelated utilities it may not need as much
documentation.

Regards,

Matt.




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