sched/core: Disable CONFIG_SCHED_CORE by default

This option at minimum adds extra code to the scheduler - even if
it's default unused - and most users wouldn't want it.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt
index bd7c4147b9a8105e15e081687c4e7217f37c3aec..5876e30c5740d8ff52de11407fc283d7d2b4e838 100644 (file)
--- a/kernel/Kconfig.preempt
+++ b/kernel/Kconfig.preempt
@@ -102,7 +102,6 @@ config PREEMPT_DYNAMIC
 
 config SCHED_CORE
        bool "Core Scheduling for SMT"
-       default y
        depends on SCHED_SMT
        help
          This option permits Core Scheduling, a means of coordinated task
@@ -115,7 +114,8 @@ config SCHED_CORE
           - mitigation of some (not all) SMT side channels;
           - limiting SMT interference to improve determinism and/or performance.
 
-         SCHED_CORE is default enabled when SCHED_SMT is enabled -- when
-         unused there should be no impact on performance.
+         SCHED_CORE is default disabled. When it is enabled and unused,
+         which is the likely usage by Linux distributions, there should
+         be no measurable impact on performance.