Commit a50a3f4b authored Jul 17, 2019 by Thomas Gleixner Committed by Ingo Molnar Jul 18, 2019

sched/rt, Kconfig: Introduce CONFIG_PREEMPT_RT



Add a new entry to the preemption menu which enables the real-time support
for the kernel. The choice is only enabled when an architecture supports
it.

It selects PREEMPT as the RT features depend on it. To achieve that the
existing PREEMPT choice is renamed to PREEMPT_LL which select PREEMPT as
well.

No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Paul E. McKenney <paulmck@linux.ibm.com>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Clark Williams <williams@redhat.com>
Acked-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Daniel Wagner <wagi@monom.org>
Acked-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
Acked-by: Julia Cartwright <julia@ni.com>
Acked-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Acked-by: Gratian Crisan <gratian.crisan@ni.com>
Acked-by: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Andrew Morton <akpm@linuxfoundation.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Tejun Heo <tj@kernel.org>
Link: http://lkml.kernel.org/r/alpine.DEB.2.21.1907172200190.1778@nanos.tec.linutronix.de


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent e3d85487

arch/Kconfig

+3 −0

Original line number	Diff line number	Diff line
		@@ -801,6 +801,9 @@ config ARCH_NO_COHERENT_DMA_MMAP
		config ARCH_NO_PREEMPT
		bool

		config ARCH_SUPPORTS_RT
		bool

		config CPU_NO_EFFICIENT_FFS
		def_bool n

kernel/Kconfig.preempt

+23 −2

Original line number	Diff line number	Diff line
		@@ -35,10 +35,10 @@ config PREEMPT_VOLUNTARY

		Select this if you are building a kernel for a desktop system.

		config PREEMPT
		config PREEMPT_LL
		bool "Preemptible Kernel (Low-Latency Desktop)"
		depends on !ARCH_NO_PREEMPT
		select PREEMPT_COUNT
		select PREEMPT
		select UNINLINE_SPIN_UNLOCK if !ARCH_INLINE_SPIN_UNLOCK
		help
		This option reduces the latency of the kernel by making
		@@ -55,7 +55,28 @@ config PREEMPT
		embedded system with latency requirements in the milliseconds
		range.

		config PREEMPT_RT
		bool "Fully Preemptible Kernel (Real-Time)"
		depends on EXPERT && ARCH_SUPPORTS_RT
		select PREEMPT
		help
		This option turns the kernel into a real-time kernel by replacing
		various locking primitives (spinlocks, rwlocks, etc.) with
		preemptible priority-inheritance aware variants, enforcing
		interrupt threading and introducing mechanisms to break up long
		non-preemptible sections. This makes the kernel, except for very
		low level and critical code pathes (entry code, scheduler, low
		level interrupt handling) fully preemptible and brings most
		execution contexts under scheduler control.

		Select this if you are building a kernel for systems which
		require real-time guarantees.

		endchoice

		config PREEMPT_COUNT
		bool

		config PREEMPT
		bool
		select PREEMPT_COUNT

Admin message