Re: [PATCH v7 4/8] powerpc/smp: Introduce CONFIG_SCHED_MC to guard MC scheduling bits

On Mon, Sep 01, 2025 at 10:35:07AM +0200, Peter Zijlstra wrote:

On Thu, Aug 28, 2025 at 08:13:51PM +0530, Shrikanth Hegde wrote:

quoted

quoted

--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig

@@ -170,6 +170,9 @@ 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

Wondering if this SCHED_MC is necessary here? shouldn't it be set by arch/Kconfig?

Ah, so without this SCHED_MC becomes a user selectable option, with this
it is an always on option (for ppc64) -- no user prompt.

That is, this is the only way I found to have similar semantics to this:

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-config SCHED_MC
-	def_bool y
-	depends on PPC64 && SMP
-

Which is also not a user selectable option.

quoted

nit: Also, can we have so they are still sorted?
	select ARCH_SUPPORTS_SCHED_MC		if PPC64 && SMP
	select ARCH_SUPPORTS_SCHED_SMT		if PPC64 && SMP

Sure, let me flip them. I need to prod that that patch anyway, built
robot still ain'ted happy.

Looks like 44x/iss476-smp_defconfig (iow 32bit power) also wants
SCHED_MC, so it should be:

config SCHED_MC
	def_bool y
	depends on SMP

Its just SMT that's a PPC64 special.