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Commit a50a3f4b authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Ingo Molnar
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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: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarPaul E. McKenney <paulmck@linux.ibm.com>
Acked-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: default avatarClark Williams <williams@redhat.com>
Acked-by: default avatarDaniel Bristot de Oliveira <bristot@redhat.com>
Acked-by: default avatarFrederic Weisbecker <frederic@kernel.org>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Acked-by: default avatarDaniel Wagner <wagi@monom.org>
Acked-by: default avatarLuis Claudio R. Goncalves <lgoncalv@redhat.com>
Acked-by: default avatarJulia Cartwright <julia@ni.com>
Acked-by: default avatarTom Zanussi <tom.zanussi@linux.intel.com>
Acked-by: default avatarGratian Crisan <gratian.crisan@ni.com>
Acked-by: default avatarSebastian 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: default avatarIngo 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