[systemd-devel] Can bootchart take advantage of startup completed signal?

[Kok, Auke-jan H]

On Wed, Feb 13, 2013 at 12:27 AM, Umut Tezduyar <umut at tezduyar.com> wrote:
> Hi Auke,
>
> I was wondering if you have tried to take advantage of StartupFinished
> signal sent by systemd
> (http://www.freedesktop.org/wiki/Software/systemd/dbus).
>
> Would it make sense to register on "StartupFinished" signal and stop taking
> measurements when systemd boots up completely? This would be an alternate to
> "samples=" option. "samples=" option is great but one needs to know how long
> does their system take to boot up so that one can do the math by dividing
> boot up time by freq= option of bootchart. Even then this would be a rough
> estimate.
>
> Since bootchart starts even before dbus, you won't be able to register for
> the StartupFinished signal until the bus is ready. Registration could be
> done in the bootchart's while loop where the measurements are taken. Then
> the question is, would registration attempts take too much resource?

Even if we honor StartupFinished, we're still ignoring the fact that
on most systems, the UI processes and login tasks are for a large part
outside the StartupFinished time.

I'm thinking more of adding information at the point when we're about
to plot and querying systemd over dbus for various data points and
including those in the plots, which would already be an improvement
but doesn't have the need to probe for the system bus all the time.

Auke