Re: [Xenomai] application start is slower with xenomai 2.6.4 than 2.4.10

[Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>]

On Fri, Feb 13, 2015 at 08:46:48AM +0100, JK.Behnke@web.de wrote:
> Hello Gilles,
> 
> thanks for your quick response.
> 
> >> Hello,
> >>
> >> I noticed that running the same xenomai application against xenomai 2.6.4
> >> is significantly slower on start up, than it was with xenomai 2.4.10.
> >> Calling my xenomai application 100 times by a bash script takes about
> >> 1 sec on xenomai 2.4.10. On xenomai 2.6.4 however it takes about
> >> 20 secs.
> >
> >On what hardware? What architecture?
> It's a Kontron nano-ETX module with an Intel Atom Z510 1,1 GHz.
> Mass storage is a 16 GB SSD attached via SATA.
> 
> 
> >> Even if I strip down my application to the absolut minimum of xenomai
> >> calls like this
> >
> >As you may know, everything is loaded on demand, so the application
> >start time does not depend on the application size.
> 
> I didn't mean the application size. I just wanted to rule out other
> xenomai calls like rt_dev_open, rt_dev_read, etc. to be responsible for
> the additional delay.
> 
> >>
> >> main()
> >> {
> >>   mlockall(...);
> >>   rt_task_shadow(...);
> >> }
> >>
> >> I get the same behaviour.
> >>
> >> I have tested this on the same hardware (x86, atom). The only difference
> >> is the Linux kernel (2.6.30.8 vs 3.14.17) version and the xenomai version
> >> (2.4.10 vs 2.6.4).
> >>
> >> I once mistakenly linked my xenomai 2.4.10 application against libxenomai
> >> and also got the same behaviour (slower startup).
> >> So I suspect this has something to do with libxenomai I need to link
> >> against, when building xenomai applications using xenomai 2.6.4.
> >>
> >> Is there a kind of additional setup behind the scenes in xenomai 2.6.4?
> >
> >The code source is available, so you can check what happens at
> >startup and even time it. I am afraid people who care about start
> >time with Xenomai are not numerous.
> >--
> >Gilles.
> 
> I have no experience with xenomai sources.
> Can you please point me out at which source file(s) to look at.
> How can I debug the startup timing?

First note that by running application in a loop you test not only
the startup time, but also the shutdown type, and this one contains
at least a nanosleep to flush the per-thread stdio buffers.

To find everything which is executed before main, you can grep the
sources for __attribute__((constructor))

-- 
					    Gilles.