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[46.139.12.213]) by smtp.gmail.com with ESMTPSA id e19sm30406864wra.71.2019.07.16.15.58.10 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Tue, 16 Jul 2019 15:58:11 -0700 (PDT) Date: Wed, 17 Jul 2019 00:58:09 +0200 From: Ingo Molnar To: Thomas Gleixner Cc: Linus Torvalds , LKML , Andrew Morton , Greg Kroah-Hartman , Peter Zijlstra , Steven Rostedt , Sebastian Siewior , Paul McKenney , Christoph Hellwig , Tejun Heo , Lukas Bulwahn , Daniel Wagner , Tom Zanussi , Daniel Bristot de Oliveira , Clark Williams , Julia Cartwright , Marc Zyngier , Frederic Weisbecker Subject: Re: [patch 1/1] Kconfig: Introduce CONFIG_PREEMPT_RT Message-ID: <20190716225809.GA50617@gmail.com> References: <20190715150402.798499167@linutronix.de> <20190715150601.205143057@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190715150601.205143057@linutronix.de> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Thomas Gleixner wrote: > 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 > --- > arch/Kconfig | 3 +++ > kernel/Kconfig.preempt | 25 +++++++++++++++++++++++-- > 2 files changed, 26 insertions(+), 2 deletions(-) > > --- a/arch/Kconfig > +++ b/arch/Kconfig > @@ -809,6 +809,9 @@ config ARCH_NO_COHERENT_DMA_MMAP > config ARCH_NO_PREEMPT > bool > > +config ARCH_SUPPORTS_RT > + bool > + > config CPU_NO_EFFICIENT_FFS > def_bool n > > --- a/kernel/Kconfig.preempt > +++ b/kernel/Kconfig.preempt > @@ -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 s/etc/etc. > + preemptible priority-inheritance aware variants, enforcing > + interrupt threading and introducing mechanisms to break up long > + non-preemtible sections. This makes the kernel, except for very s/preemtible/preemptible > + low level and critical code pathes (entry code, scheduler, low > + level interrupt handling) fully preemtible and brings most s/preemtible/preemptible > + execution contexts under scheduler control. > + > + Select this if you are building a kernel for systems which > + require real-time guarantees. Nice to see this getting started! :-) Acked-by: Ingo Molnar Thanks, Ingo