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