Re: [PATCH RESEND 0/3] Represent cluster topology and enable load balance between clusters

[Valentin Schneider]

On 05/10/21 14:42, Valentin Schneider wrote:
> On 05/10/21 09:50, Peter Zijlstra wrote:
>> On Fri, Oct 01, 2021 at 04:22:46PM -0700, Tim Chen wrote:
>>> On Fri, 2021-10-01 at 16:57 +0200, Peter Zijlstra wrote:
>>
>>> > The one questino I have is, do we want default y?
>>>
>>> I also agree that default y is preferable.
>>
>> I'll change at least the x86 one to:
>>
>>       default y
>>       depends on SMP
>>
>
> Huh, so the arm64 SCHED_{SMT,MC} configs are defaultless (I added SCHED_SMT
> to arm64's defconfig not so long ago), but x86 has them default y, which
> I'm thinking is a tad better, and would be nice to harmonize. Unfortunately
> different architectures have their own dependency requirements - arm has
> ARM_CPU_TOPOLOGY, parisc has PARISC_CPU_TOPOLOGY...
>
> Would you hate making SCHED_* a "generic" config, with a common default and
> help text, and punt the arch specific stuff to an ARCH_SUPPORTS_* knob?
>
> Something like:
>
> arch/arm/Kconfig:
>   select ARCH_SUPPORTS_SCHED_MC if ARM_CPU_TOPOLOGY
>
> init/Kconfig:
>   config SCHED_MC
>     def_bool y
>     depends on ARCH_SUPPORTS_SCHED_MC && SMP

... Which is essentially what Barry suggested somewhere else in the thread
(I TL; DR'd).