On Jan 29, 2008 9:09 AM, Juan Antonio Garcia Redondo
<[EMAIL PROTECTED]> wrote:
>
> On 28/01/08 14:19, Gilles Chanteperdrix wrote:
> > > >
> > > >
> > > > > > No mystery: hitting a key on a telnet session causes an interrupt
> > > > > > masking section of 110us, you see it as the maximum if you never
> > > > > > observed longer masking sections, but it is not the maximum if you
> > > > > > observed longer masking sections.
> > > > >
> > > > > OK, but why the masking section on linux side affects to xenomai side
> > > > > ?
> > > > > Another thing I don't understand is why when the system has load
> > > > > (above
> > > > > I'm talking about calibrator but the same occurs with dd if=/dev/zero
> > > > > of=/dev/null), the effect seems to dissapear.
> > > >
> > > > It is probably not a masking section on linux side but rather a
> > > > masking section on I-pipe side. Anyway, the effect does not disappear:
> > > > it means that the cache effects cause larger latencies than the
> > > > ethernet interrupt, but maybe I did not understand what you explained.
> > > > The results you obtain with no load are simply irrelevant.
> > >
> > > I'll try to explain it better:
> > >
> > > o Without load I run ./latency -t0 -p500.
> > > RTD| 33.182| 53.479| 67.976| 0| 31.250| 77.319
> > > RTD| 43.170| 53.479| 67.654| 0| 31.250| 77.319
> > > RTD| 41.881| 53.479| 67.332| 0| 31.250| 77.319
> > > RTT| 00:02:07 (periodic user-mode task, 500 us period, priority 99)
> > >
> > > o Each time I press a key (over a telnet session) I can see the lat_max
> > > field increase on 40 to 50 us aprox.
> > > RTD| 33.505| 53.479| 71.842| 0| 26.739| 77.319
> > > RTD| 40.592| 62.177| 123.067| 0| 26.739| 123.067
> > > -------
> > > \_________: Key pressed
> > > RTD| 50.579| 53.479| 73.775| 0| 26.739| 123.067
> >
> > This is where you are wrong:
> > - first, let me repeat it: test made without load are irrelevant;
> I can't agree with you. When we stress a system with load is, as far as
> I know, because usually, the large latencies don't appear on a quiet
> system.
Wrong: they are less likely to appear, but may appear as well.
--
Gilles Chanteperdrix
_______________________________________________
Xenomai-help mailing list
[email protected]
https://mail.gna.org/listinfo/xenomai-help
