[systemd-devel] [HEADSUP] systemd-analyze in git

[Lennart Poettering]

Heya,

I just added "systemd-analyze" to git. It's a little Python tool which
can help you figuring out why your boot is not as fast as it could be.

If you run "systemd-analyze blame" it will print a list of all units
that have been started since boot, ordered by the time they took to
start up. If your service appears right at the top of the list, then
there's probably something to fix. But don't misunderstand this tool. It
will simply look how long each service took to start, it doesn't give
you any hint on why it did take so long. For example it could be because
the service was waiting for another service or for user input (for
example in the cryptsetup case). So, take the output with a grain of
salt and then it is quite interesting. Let the blame game begin!

If you run "systemd-analyze plot > plot.svg && eog plot.svg" then you'll
look at a graphical plot of the boot processes showing how long we had
to had to wait for which unit to start up. The startup time will be
visible as a bright red bar. The runtime of a unit will be shown in
light pink. The output is a bit like bootchart, but on a very different
level, as this tells you something about the ordering and the units in
systemd. To optimize your boot process you probably want to look at both
outputs.

For this to work properly you need to run systemd from git. Older
versions of systemd do not keep track of timestamps properly, and this
is fixed in git.

On an older X300 with SSD and a reasonably complete Linux installation
systemd needs less than 1s to spawn all services at boot and enter idle
mode. If your installation takes longer, then you probably have a lot of
room for optimization. (1s to idle does not mean the bootup was
complete. It just means systemd started all processes it needed to start
and the machine might still be busy with those. But early boot/fsck and
stuff is all finished as are all SysV scripts, and graphical.target is
reached).

Lennart

--
Lennart Poettering - Red Hat, Inc.