On Thu, Aug 28, 2025 at 08:13:51PM +0530, Shrikanth Hegde wrote: > > --- 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: > > -config SCHED_MC > > - def_bool y > > - depends on PPC64 && SMP > > - Which is also not a user selectable option. > 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. > > --- a/arch/s390/Kconfig > > +++ b/arch/s390/Kconfig > > @@ -547,15 +547,11 @@ config NODES_SHIFT > > depends on NUMA > > default "1" > > -config SCHED_SMT > > - def_bool n > > - > > -config SCHED_MC > > - def_bool n > > - > > config SCHED_TOPOLOGY > > def_bool y > > prompt "Topology scheduler support" > > + select ARCH_SUPPORTS_SCHED_SMT > > + select ARCH_SUPPORTS_SCHED_MC > > select SCHED_SMT > > select SCHED_MC > Same here. Above two are needed? Same issue; previously neither were user selectable symbols. By only selecting the ARCH_SUPPORTS_$FOO variants, the $FOO options become user selectable. By then explicitly selecting $FOO as well, that user option is taken away again. > > --- a/arch/x86/Kconfig > > +++ b/arch/x86/Kconfig > > @@ -330,6 +330,10 @@ config X86 > > imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI > > select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE > > select ARCH_SUPPORTS_PT_RECLAIM if X86_64 > > + select ARCH_SUPPORTS_SCHED_SMT if SMP > > + select SCHED_SMT if SMP > Is this SCHED_SMT needed here? Same again... > > + select ARCH_SUPPORTS_SCHED_CLUSTER if SMP > > + select ARCH_SUPPORTS_SCHED_MC if SMP > > config INSTRUCTION_DECODER > > def_bool y > > @@ -1036,29 +1040,6 @@ config NR_CPUS > > This is purely to save memory: each supported CPU adds about 8KB > > to the kernel image. > > -config SCHED_CLUSTER > > - bool "Cluster scheduler support" > > - depends on SMP > > - default y > > - help > > - Cluster scheduler support improves the CPU scheduler's decision > > - making when dealing with machines that have clusters of CPUs. > > - Cluster usually means a couple of CPUs which are placed closely > > - by sharing mid-level caches, last-level cache tags or internal > > - busses. > > - > > -config SCHED_SMT > > - def_bool y if SMP > > - > > -config SCHED_MC > > - def_bool y > > - prompt "Multi-core scheduler support" > > - depends on SMP > > - help > > - Multi-core scheduler support improves the CPU scheduler's decision > > - making when dealing with multi-core CPU chips at a cost of slightly > > - increased overhead in some places. If unsure say N here. See how SCHED_SMT is not a user option for x86.
