Re: [Xenomai-help] How to solve this high latency problem

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

子 小 wrote:
> Hi,
> 
> after I installed the xenomai-2.5.1 with kernel 2.6.32.7, I ran the
> latency test program at /usr/xenomai/share/xenomai/testsuite/latency
> 
> below is what I got. High latency (about 400 microseconds for max
> latency) is present.
> 
> Basically, in my configuration, I have disabled ACPI, APM, and CPU
> frequency scaling;

You should NOT disable ACPI. The only thing you should disable is
ACPI_PROCESSOR.

> enalbed "Enable periodic timing", "Enable FPU support", and "Enable
> NMI watchdog".

You probably do not need the periodic timer.

> 
> I know that SMI workaround is important here. So I also enabled
> "Enable SMI workaround". Regarding "Globally disable SMI", I tried
> many times and found that if I enabled it, my laptop cannot boot
> up... Thus I have to keep it disabled, while I did not enable any
> other SMI options below "Globally disable SMI" in the configuration
> menu.
> 
> Now I am stuck here, not able to find out the solution to the
> problem. Could you help on this?

See xenomai troubleshooting guide.

> 
> Another question I would like to ask: in the result of my latency
> test, what is the difference between "lat max" and "lat worst"?
> because the numbers shown there are different.

the max is the max during the last second, the worst is the max since
the latency program is running.


-- 
Gilles Chanteperdrix, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com