Re: [PATCH 1/4] build: Hook the schedulers into Kconfig

[Dario Faggioli <dario.faggioli@citrix.com>]

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On Thu, 2015-12-17 at 14:59 -0600, Jonathan Creekmore wrote:
> Allow the schedulers to be independently enabled or disabled at
> compile-time instead of just allowing the scheduler to be selected on
> the command line. 
>
Reading this quickly, that "instead" gave me a bit of an hard time. I'm
not a native English speaker, and I'm sure it's me that am wrong, but
for some reason the sentence made me think that the patch would somehow
disallow specifying a scheduler during boot, in Xen's command line.

Fact is, I don't think the phrase "instead of just allowing the
scheduler to be selected on the command line." adds much information,
and I'd just remove it.

> To match existing behavior, all four schedulers are
> compiled in by default, although the RTDS and ARINC653 are marked
> EXPERIMENTAL to match their not currently supported status.
> 
This may change shortly, but as of now, Credit2 is still experimental
too. I think I'd still recommend enabling it in the help file (i.e.,
I'm ok with "If unsure, say Y"), but we certainly should mark it with
"(EPERIMENTAL)".

I don't know much on how kconfig works, so all the changes to the
makefile, etc, I'm not able to review them properly.

On the other hand, the code here below...

> --- a/xen/common/schedule.c
> +++ b/xen/common/schedule.c
> @@ -38,8 +38,8 @@
>  #include <public/sched.h>
>  #include <xsm/xsm.h>
>  
> -/* opt_sched: scheduler - default to credit */
> -static char __initdata opt_sched[10] = "credit";
> +/* opt_sched: scheduler - default to configured value */
> +static char __initdata opt_sched[10] = CONFIG_SCHED_DEFAULT;
>  string_param("sched", opt_sched);
>  
>  /* if sched_smt_power_savings is set,
> @@ -65,10 +65,18 @@ DEFINE_PER_CPU(struct schedule_data,
> schedule_data);
>  DEFINE_PER_CPU(struct scheduler *, scheduler);
>  
>  static const struct scheduler *schedulers[] = {
> +#ifdef CONFIG_SCHED_CREDIT
>      &sched_credit_def,
> +#endif
> +#ifdef CONFIG_SCHED_CREDIT2
>      &sched_credit2_def,
> +#endif
> +#ifdef CONFIG_SCHED_ARINC653
>      &sched_arinc653_def,
> +#endif
> +#ifdef CONFIG_SCHED_RTDS
>      &sched_rtds_def,
> +#endif
>  };
>  
... can have, with the changelog changed as shown, my:

 Acked-by: Dario Faggioli <dario.faggioli@citrix.com>

Regards,
Daio
-- 
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)


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