[systemd-devel] Bootchart speeding up boot time

[Martin Townsend]

I'm using a physical stopwatch and running it from the moment U-Boot hands
over until I get a prompt so I'm not taking any timing information from
systemd or even the system itself.  I'm sure that glibc does indeed take
some time to load into memory but I can't see it being the culprit of an
8-9 second difference.  Even without a stopwatch you can easily see the
speed difference when it boots by the speed that the systemd messages
appear so I think it's something more fundamental.  Or am I missing
something here?

Cheers, Martin.

On Mon, Feb 22, 2016 at 9:20 PM, Kok, Auke-jan H <auke-jan.h.kok at intel.com>
wrote:

> On Mon, Feb 22, 2016 at 11:51 AM, Martin Townsend
> <mtownsend1973 at gmail.com> wrote:
> > Hi,
> >
> > Thanks for your reply.  I wouldn't really call this system stripped
> down, it
> > has an nginx webserver, DHCP server, postgresql-server, sftp server, a
> few
> > mono (C#) daemons running, loads quite a few kernel modules during boot,
> > dbus, sshd, avahi, and a bunch of other stuff I can't quite remember.  I
> > would imagine glibc will be a tiny portion of what gets loaded during
> boot.
> > I have another arm system which has a similar boot time with systemd,
> it's
> > only a single cortex A9 core, it's running a newer 4.1 kernel with a new
> > version of systemd as it's built with the Jethro version of Yocto so
> > probably a newer version of glibc and this doesn't speed up when using
> > bootchart and in fact slows down slightly (which is what I would expect).
> > So my current thinking is that it's either be down to the fact that it's
> a
> > dual core and only one core is being used during boot unless a fork/execl
> > occurs? Or it's down to the newer kernel/systemd/glibc or some other
> > component.
> >
> > Is there anyway of seeing what the CPU usage for each core is for
> systemd on
> > boot without using bootchart then I can rule in/out the first idea.
>
> Not that I know of, but, to work around the issue of dynamic linking,
> one can link systemd-bootchartd statically. It'll become larger, but
> you can then clearly ascern that the impact of glibc bits being loaded
> are properly recorded by bootchart. And, it's fairly trivial link it
> statically.
>
> Auke
>
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