From 9c18f59d9daddc8c6090bb0f1d60bcb6e320deb9 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Sun, 25 Nov 2018 19:33:37 +0100 Subject: [PATCH] x86/Kconfig: Select SCHED_SMT if SMP enabled commit dbe733642e01dd108f71436aaea7b328cb28fd87 upstream. 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 Reviewed-by: Ingo Molnar Cc: Peter Zijlstra Cc: Andy Lutomirski Cc: Linus Torvalds Cc: Jiri Kosina Cc: Tom Lendacky Cc: Josh Poimboeuf Cc: Andrea Arcangeli Cc: David Woodhouse Cc: Tim Chen Cc: Andi Kleen Cc: Dave Hansen Cc: Casey Schaufler Cc: Asit Mallick Cc: Arjan van de Ven Cc: Jon Masters Cc: Waiman Long Cc: Greg KH Cc: Dave Stewart Cc: Kees Cook Link: https://lkml.kernel.org/r/20181125185004.337452245@linutronix.de [bwh: Backported to 3.16: CONFIG_SCHED_SMT depended on CONFG_X86_HT, but that also follows CONFIG_SMP] Signed-off-by: Ben Hutchings --- arch/x86/Kconfig | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 22512bbc5a41..9ae6b38b8361 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -798,13 +798,7 @@ config NR_CPUS approximately eight kilobytes to the kernel image. config SCHED_SMT - bool "SMT (Hyperthreading) scheduler support" - depends on X86_HT - ---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