Thread (41 messages) 41 messages, 7 authors, 2025-10-14

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

From: K Prateek Nayak <kprateek.nayak@amd.com>
Date: 2025-09-01 04:40:17
Also in: linux-s390, lkml

Hello Shrikanth,

On 8/29/2025 2:23 PM, 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?
I think this makes sense.

FWIW, Peter added the "select SCHED_MC" to keep it consistent with the
current behavior.
quoted hunk ↗ jump to hunk
---
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
When I was looking at this, the whole of .*coregroup.* related bits in
smp.c can technically go behind CONFIG_SCHED_MC too but that is a much
larger cleanup and perhaps unnecessary too so this looks good.

-- 
Thanks and Regards,
Prateek

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