Julien Heyman wrote:
> Hi,
>
> I am currently trying to evaluate Xenomai, and my current setup is :
> VIA C3 533Mhz processor, Kubuntu 6.06 Linux distribution.
> I am using Xenomai-2.1.0 over a 2.6.17.4 kernel.
> When I run the latency part of the testsuite (in a console under KDE), I get
> results that I cannot understand, so I probably did something wrong
> (execution trace included below).
> I get reasonable values during the first seconds, then all of a sudden
> latencies begin to rise, continuously, to very large values.
> - I did check that DMA transfer is activated on my HD.
> - I did select "Enable SMI workaround" + "Globally disable SMI" in the
> Xenomai
> options while configuring the kernel.
> - I have disabled power management at BIOS level and disabled ACPI support
> and
> CPU frequency scaling during kernel configuration.
> - I checked that I don't have anything called "legacy USB" in my BIOS. I do
> have an "OnChip USB" option enable in the BIOS though.
>
> Any advice would be appreciated !
Some platforms stop their tsc when idle, this would cause serious
trouble for Xenomai. Linux detect such behaviour and print the message:
Losing too many ticks!
TSC cannot be used as a timesource.
Possible reasons for this are:
You're running with Speedstep,
You don't have DMA enabled for your hard disk (see hdparm),
Incorrect TSC synchronization on an SMP system (see dmesg).
Falling back to a sane timesource now.
Do you see such message in kernel logs ?
If this is the issue you are having, then you may try passing idle=poll
on kernel boot line. Or recompile the kernel selecting a processor that
has no tsc (for example 486), xenomai will then use the 8254 counter to
emulate the tsc.
--
Gilles Chanteperdrix.
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