Re: [PATCH v7 0/8] sched/fair: Get rid of sched_domains_curr_level hack for tl->cpumask()

[Shrikanth Hegde <sshegde@linux.ibm.com>]

On 9/1/25 2:28 PM, Peter Zijlstra wrote:
> On Fri, Aug 29, 2025 at 02:23:06PM +0530, Shrikanth Hegde wrote:
> 
>> I was looking at: https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git/log/?h=sched/core
>>
>> Current code doesn't allow one to enable/disable SCHED_MC on ppc since it is set always in kconfig.
>> Used the below patch:
>>
>> I think since the config is there, it would be good to provide a option to disable. no?
> 
> So current PPC code has this MC thing unconditional. I've been
> preserving that behaviour. If PPC maintainers feel they want this
> selectable, I'm happy to include something like the below, but as a
> separate patch with a separate changelog that states this explicit
> choice.
> 

Fair enough. Will send it as separate patch.

>> ---
>>
>> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
>> index fc0d1c19f5a1..da5b2f8d3686 100644
>> --- a/arch/powerpc/Kconfig
>> +++ b/arch/powerpc/Kconfig
>> @@ -170,9 +170,8 @@ config PPC
>>   	select ARCH_STACKWALK
>>   	select ARCH_SUPPORTS_ATOMIC_RMW
>>   	select ARCH_SUPPORTS_DEBUG_PAGEALLOC	if PPC_BOOK3S || PPC_8xx
>> -	select ARCH_SUPPORTS_SCHED_SMT		if PPC64 && SMP
>>   	select ARCH_SUPPORTS_SCHED_MC		if PPC64 && SMP
>> -	select SCHED_MC				if ARCH_SUPPORTS_SCHED_MC
>> +	select ARCH_SUPPORTS_SCHED_SMT		if PPC64 && SMP
>>   	select ARCH_USE_BUILTIN_BSWAP
>>   	select ARCH_USE_CMPXCHG_LOCKREF		if PPC64
>>   	select ARCH_USE_MEMTEST
>> diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
>> index 68edb66c2964..458ec5bd859e 100644
>> --- a/arch/powerpc/kernel/smp.c
>> +++ b/arch/powerpc/kernel/smp.c
>> @@ -1706,10 +1706,12 @@ static void __init build_sched_topology(void)
>>   			SDTL_INIT(tl_cache_mask, powerpc_shared_cache_flags, CACHE);
>>   	}
>> +#ifdef CONFIG_SCHED_MC
>>   	if (has_coregroup_support()) {
>>   		powerpc_topology[i++] =
>>   			SDTL_INIT(tl_mc_mask, powerpc_shared_proc_flags, MC);
>>   	}
>> +#endif
>>   	powerpc_topology[i++] = SDTL_INIT(tl_pkg_mask, powerpc_shared_proc_flags, PKG);
>>


If possible for below two, please consider tags.

https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git/commit/?h=sched/core&id=496d4cc3d478a662f90cce3a3e3be4af56f78a02
https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git/commit/?h=sched/core&id=a912f3e2c6d91f7ea7b294c02796b59af4f50078

Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>

for powerpc bits:
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com>