Re: [Xenomai-help] Time between ISR and RT Task

[newsletter <gsm909@domain.hid>]

Sorry

My System:
MPC8270 (PowerPC)
with uboot

Denx Linux und Xenomai Realtime Framework :)

thx for Helping


Gilles Chanteperdrix wrote:
> GSM909@domain.hid wrote:
>  > GSM909@domain.hid wrote:
>  >  > Hello
>  >  >
>  >  > I have run a few programs with Xenomai tasks and have no problems. But I notice that the time between ISR and RT task ( RT task is suspended and resumed by the ISR) is shorter when Linux have a lot of work ( average load around 10 ) as when Linux has nothing to do( al : 0.05 ). 
>  > 
>  > Do you observe this for worst case, or for average case latencies? Do you observe this when you boot with the idle=poll parameter ?
>  > 
>  > When idle, Linux uses the 'hlt' instruction, that stops the CPU until an interrupt happen, maybe waking up from this state take a little bit more time than when an interrupt is received directly?
>  > 
>  > How can I set idel = poll ?
>
> That's idle, not idel. The way to pass this option to the kernel depend
> on the bootloader you are using. If using lilo on x86, add a line:
>
> append="idle=poll"
>
> to the /etc/lilo.conf section for the image you are booting (if there is
> already an "append" line, then add "idle=poll" to this line)
>
> If using grub on x86, add idle=poll to the /boot/grub/menu.lst line
> beginning with "kernel" for the xenomai kernel.
>
> Anyway, you should let the latency test run a few hours for a given
> configuration before concluding anything, the worst case latency does
> not show up so easily.
>
>