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

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

[子 小]

[-- Attachment #1: Type: text/plain, Size: 2758 bytes --]


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

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?

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.

Best Regards,
Henry


== Sampling period: 100 us
== Test mode: periodic user-mode task
== All results in microseconds
warming up...
RTT|  00:00:01  (periodic user-mode task, 100 us period, priority 99)
RTH|----lat min|----lat avg|----lat max|-overrun|---msw|---lat best|--lat worst
RTD|      0.848|      1.020|    358.154|       3|     0|      0.848|    358.154
RTD|      0.749|      0.983|     15.540|       3|     0|      0.749|    358.154
RTD|      0.785|      1.017|    369.927|       6|     0|      0.749|    369.927
RTD|      0.745|      0.986|     11.431|       6|     0|      0.745|    369.927
RTD|      0.745|      1.014|    376.297|       9|     0|      0.745|    376.297
RTD|      0.778|      0.979|     15.137|       9|     0|      0.745|    376.297
RTD|      0.540|      1.020|    385.877|      12|     0|      0.540|    385.877
RTD|      0.842|      1.002|     11.561|      12|     0|      0.540|    385.877
RTD|      0.748|      1.014|    391.803|      15|     0|      0.540|    391.803
RTD|      0.784|      0.976|     16.482|      15|     0|      0.540|    391.803
RTD|      0.840|      1.015|    403.156|      19|     0|      0.540|    403.156
RTD|      0.583|      0.997|     16.902|      19|     0|      0.540|    403.156
RTD|      0.846|      1.029|    314.282|      22|     0|      0.540|    403.156
RTD|      0.723|      0.975|     14.964|      22|     0|      0.540|    403.156
^C---|-----------|-----------|-----------|--------|------|-------------------------
RTS|      0.540|      1.001|    403.156|      22|     0|    00:00:14/00:00:14

 		 	   		  
_________________________________________________________________
Hotmail: Trusted email with powerful SPAM protection.
https://signup.live.com/signup.aspx?id=60969

[-- Attachment #2: Type: text/html, Size: 5360 bytes --]

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

[Gilles Chanteperdrix]

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