Intel Turbo Mode

Intel Turbo Mode

[cagnulein]

Hi everybody,
  i would like to give my contribution to this incredible project.
 In these days i'm working on a Intel Atom E3930 (2 cores 1.3GHz with Turbo
Mode to 1.8GHz) and Xenomai.
 Everything working flawless, except the turbo mode.
 Infact, in order to enabling the turbo mode, with the vanilla kernel, i
have to enabling ACPI Processor causing high latency on Xenomai (over 350
us).

 I've create a patch for the vanilla kernel, that allows to enabling the
Turbo Mode without adding the ACPI Processor!
 In this way i can have cpu at maximum speed with a deterministic and low
latency (under 36 us!).

 Here you can find the patch. Maybe you can add it on ipipe?

 Roberto
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Re: Intel Turbo Mode

[Jan Kiszka]

On 26.02.19 17:35, cagnulein via Xenomai wrote:
> Hi everybody,
>    i would like to give my contribution to this incredible project.
>   In these days i'm working on a Intel Atom E3930 (2 cores 1.3GHz with Turbo
> Mode to 1.8GHz) and Xenomai.
>   Everything working flawless, except the turbo mode.
>   Infact, in order to enabling the turbo mode, with the vanilla kernel, i
> have to enabling ACPI Processor causing high latency on Xenomai (over 350
> us).
> 
>   I've create a patch for the vanilla kernel, that allows to enabling the
> Turbo Mode without adding the ACPI Processor!
>   In this way i can have cpu at maximum speed with a deterministic and low
> latency (under 36 us!).
> 
>   Here you can find the patch. Maybe you can add it on ipipe?
> 

Thanks for your contribution! We can consider adding this, I would just like to 
double-check first if there aren't also patch-free ways today:

I always wanted to try out the runtime tunings described e.g. on 
https://wiki.linuxfoundation.org/realtime/documentation/howto/applications/cpuidle 
to see if we could relax our build-time feature-exclusion set and rather do that 
tuning e.g. on Xenomai application startup.

Would you be interested in in playing with such an approach?

Jan

-- 
Siemens AG, Corporate Technology, CT RDA IOT SES-DE
Corporate Competence Center Embedded Linux

Re: Intel Turbo Mode

[cagnulein]

Thank you for the proposal but I don't have more spare time right now. I
hope to help you in the future.
Roberto Viola

Il mar 26 feb 2019, 19:41 Jan Kiszka <jan.kiszka@siemens.com> ha scritto:

> On 26.02.19 17:35, cagnulein via Xenomai wrote:
> > Hi everybody,
> >    i would like to give my contribution to this incredible project.
> >   In these days i'm working on a Intel Atom E3930 (2 cores 1.3GHz with
> Turbo
> > Mode to 1.8GHz) and Xenomai.
> >   Everything working flawless, except the turbo mode.
> >   Infact, in order to enabling the turbo mode, with the vanilla kernel, i
> > have to enabling ACPI Processor causing high latency on Xenomai (over 350
> > us).
> >
> >   I've create a patch for the vanilla kernel, that allows to enabling the
> > Turbo Mode without adding the ACPI Processor!
> >   In this way i can have cpu at maximum speed with a deterministic and
> low
> > latency (under 36 us!).
> >
> >   Here you can find the patch. Maybe you can add it on ipipe?
> >
>
> Thanks for your contribution! We can consider adding this, I would just
> like to
> double-check first if there aren't also patch-free ways today:
>
> I always wanted to try out the runtime tunings described e.g. on
>
> https://wiki.linuxfoundation.org/realtime/documentation/howto/applications/cpuidle
> to see if we could relax our build-time feature-exclusion set and rather
> do that
> tuning e.g. on Xenomai application startup.
>
> Would you be interested in in playing with such an approach?
>
> Jan
>
> --
> Siemens AG, Corporate Technology, CT RDA IOT SES-DE
> Corporate Competence Center Embedded Linux
>

Re: Intel Turbo Mode

[Alec Ari]

The kernel is a bit trigger-happy with Kconfig options, I've done similar things with other drivers. The driver developers seriously need to tune their usage of ifdef a bit. I say merge it.
Alec