[patch 09/24] x86/Kconfig: Select SCHED_SMT if SMP enabled

From: Thomas Gleixner
Date: Wed Nov 21 2018 - 15:18:19 EST


CONFIG_SCHED_SMT is enabled by all distros, so there is not a real point to
have it configurable. The runtime overhead in the core scheduler code is
minimal because the actual SMT scheduling parts are conditional on a static
key.

This allows to expose the scheduler's SMT state static key to the
speculation control code. Alternatively the scheduler's static key could be
made always available when CONFIG_SMP is enabled, but that's just adding an
unused static key to every other architecture for nothing.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
arch/x86/Kconfig | 8 +-------
1 file changed, 1 insertion(+), 7 deletions(-)

--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1000,13 +1000,7 @@ config NR_CPUS
to the kernel image.

config SCHED_SMT
- bool "SMT (Hyperthreading) scheduler support"
- depends on SMP
- ---help---
- SMT scheduler support improves the CPU scheduler's decision making
- when dealing with Intel Pentium 4 chips with HyperThreading at a
- cost of slightly increased overhead in some places. If unsure say
- N here.
+ def_bool y if SMP

config SCHED_MC
def_bool y