[Xenomai-help] [testsuite/latency] intervals are much > than 1 second

[Xenomai-help] [testsuite/latency] intervals are much > than 1 second

[Dmitry Adamushko]

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Hello all,

I have been out of xeno-scope for a while so maybe I successufy missed
something important
that might be the explanation of a problem described below.

The problem is as follows:

x86-ipipe-1.0.10 && xenomai-2.1 (CVS: ~ November, 21)

testsuite/letency is used as it is by defaulty (nsamples = 1 billion (1
second) / sample (e.g.100000 us))

I am used to getting data with ~1-second-interval on the screen when
"latency" is running and so expected to observe the same behaviour now.

Nevertheless, the interval (with all parameters by default) is ~ 4 seconds,
and it gets up to 16-17 seconds when -p 1000 (sampling period == 1 ms.) is
used.

e.g. it took 1 minute and 30 seconds to get 21 lines of statistics on the
screen (-p 100) but should have been ~22-23 seconds.

And the latency thread really reported the presence of collected data 21
times (through rt_sem_v()) .

So have I missed something important? any ideas are wellcome.

--
Best regards,
Dmitry Adamushko

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Re: [Xenomai-help] [testsuite/latency] intervals are much > than 1 second

[Philippe Gerum]

Dmitry Adamushko wrote:
> 
> Hello all,
> 
> I have been out of xeno-scope for a while so maybe I successufy missed 
> something important
> that might be the explanation of a problem described below.
> 
> The problem is as follows:
> 
> x86-ipipe-1.0.10 && xenomai-2.1 (CVS: ~ November, 21)
> 
> testsuite/letency is used as it is by defaulty (nsamples = 1 billion (1 
> second) / sample (e.g.100000 us))
> 
> I am used to getting data with ~1-second-interval on the screen when 
> "latency" is running and so expected to observe the same behaviour now.
> 
> Nevertheless, the interval (with all parameters by default) is ~ 4 
> seconds, and it gets up to 16-17 seconds when -p 1000 (sampling period 
> == 1 ms.) is used.
> 
> e.g. it took 1 minute and 30 seconds to get 21 lines of statistics on 
> the screen (-p 100) but should have been ~22-23 seconds.
> 
> And the latency thread really reported the presence of collected data 21 
> times (through rt_sem_v()) .
> 
> So have I missed something important? any ideas are wellcome.
>

Dunno yet, but this reminds me of a trap I've been into recently that 
caused a massive slowdown of the latency test (v2.0.x) whilst the 
reported real-time activity seemed to be ok. Weird enough, actually. The 
explanation was that I mistakenly left the full ACPI support and SUSPEND 
active in my kernel config (Asus box with ICH6 chipset). Shutting them 
down solved the issue. I've not investigated further which one of the 
ACPI options or SUSPEND caused that trouble yet.

> -- 
> Best regards,
> Dmitry Adamushko
> 
> 
> ------------------------------------------------------------------------
> 
> _______________________________________________
> Xenomai-help mailing list
> Xenomai-help@domain.hid
> https://mail.gna.org/listinfo/xenomai-help


-- 

Philippe.

Re: [Xenomai-help] [testsuite/latency] intervals are much > than 1 second

[Gilles Chanteperdrix]

Philippe Gerum wrote:
 > Dmitry Adamushko wrote:
 > > 
 > > Hello all,
 > > e.g. it took 1 minute and 30 seconds to get 21 lines of statistics on 
 > > the screen (-p 100) but should have been ~22-23 seconds.
 > > 
 > > And the latency thread really reported the presence of collected data 21 
 > > times (through rt_sem_v()) .
 > > 
 > > So have I missed something important? any ideas are wellcome.
 > >
 > 
 > Dunno yet, but this reminds me of a trap I've been into recently that 
 > caused a massive slowdown of the latency test (v2.0.x) whilst the 
 > reported real-time activity seemed to be ok. Weird enough, actually. The 
 > explanation was that I mistakenly left the full ACPI support and SUSPEND 
 > active in my kernel config (Asus box with ICH6 chipset). Shutting them 
 > down solved the issue. I've not investigated further which one of the 
 > ACPI options or SUSPEND caused that trouble yet.

I am observing a similar issue here; after a suspend/resume cycle,
running the latency test gives low latencies and every second is at
least two seconds long.

If I load the cpufreq module, I notice that even if when suspending,
/proc/cpuinfo indicates 1.5 GHz, after resuming, it indicates 600 MHz.

So, maybe, when doing a suspend/resume cycle without the CPUFreq modules
loaded, Linux assumes that the CPU frequency remains the same whereas
ACPI/BIOS changes it ?

-- 


					    Gilles Chanteperdrix.

Re: [Xenomai-help] [testsuite/latency] intervals are much > than 1 second

[Dmitry Adamushko]

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> > Hello all,
> >
> > I have been out of xeno-scope for a while so maybe I successufy missed
> > something important
> > that might be the explanation of a problem described below.
> >
> > The problem is as follows:
> >
> > x86-ipipe-1.0.10 && xenomai-2.1 (CVS: ~ November, 21)
> >
> > testsuite/letency is used as it is by defaulty (nsamples = 1 billion (1
> > second) / sample (e.g.100000 us))
> >
> > I am used to getting data with ~1-second-interval on the screen when
> > "latency" is running and so expected to observe the same behaviour now.
> >
> > Nevertheless, the interval (with all parameters by default) is ~ 4
> > seconds, and it gets up to 16-17 seconds when -p 1000 (sampling period
> > == 1 ms.) is used.
> >
> > e.g. it took 1 minute and 30 seconds to get 21 lines of statistics on
> > the screen (-p 100) but should have been ~22-23 seconds.
> >
> > And the latency thread really reported the presence of collected data 21
> > times (through rt_sem_v()) .
> >
> > So have I missed something important? any ideas are wellcome.
> >
>
> Dunno yet, but this reminds me of a trap I've been into recently that
> caused a massive slowdown of the latency test (v2.0.x) whilst the
> reported real-time activity seemed to be ok. Weird enough, actually. The
> explanation was that I mistakenly left the full ACPI support and SUSPEND
> active in my kernel config (Asus box with ICH6 chipset). Shutting them
> down solved the issue. I've not investigated further which one of the
> ACPI options or SUSPEND caused that trouble yet.


Thanks for a hint. I have mistakenly used an improper .config as a base for
the recently built xeno-aware kernel. ACPI support was on.

Yep, it seemed the flow of time was ~4 times slower than normally but no
overruns were encountered.

>
> --
>
> Philippe.
>

--
Best regards,
Dmitry Adamushko

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