Re: GUADEC Hacking

[Soeren Sandmann <sandmann daimi au dk>]

Jamie McCracken <jamiemcc blueyonder co uk> writes:

> > I'm a little skeptical because IIRC the mail I posted with the
> > gconf-on-startup profiling numbers only showed 2-3 seconds for GConf.
> > Which is worth fixing, but by no means explains the entire login time.
> > A good place to start for full data would be the "boot chart"
> > profiles
> > people have done.
> 
> But those just show the start up time of the daemons. Correct me if
> I'm wrong but its not easy tell from them how a big a hit they are
> causing after they are up and running?

It is correct that a boot chart would not be able to assign blame to
libraries, but it would show whether the processes running are disk or
CPU bound.

If I were to profile the login process, what I would do is modify the
kernel module from the sysprof profiler and make it take stack traces
of tasks in the UNINTERRUPTIBLE state instead of as now in the RUNNING
state. Then feed those stack traces to an unmodified sysprof and see
what the profile look like.

This would produce numbers on what pieces of code are actually causing
disk accesses. What it wouldn't account for, is which *other* pieces
of code are accessing the same memory, so the numbers would not
translate directly into blame.

Søren