From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_2 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5CDC4C7618F for ; Thu, 18 Jul 2019 19:23:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 358CB21849 for ; Thu, 18 Jul 2019 19:23:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1563477819; bh=cl4chmJfGrtFs/C/yZpzQPOkVkMTOGa0056pV1iOO1k=; h=Subject:From:To:Cc:Date:In-Reply-To:References:List-ID:From; b=EmYxc/B/SdPqovEjrLVaYH0WlfB5Pz+iKMlwrucsyHUQUXHuZ7jPUdxbeHtieuC6i CAO5mL7nwB539xJNeXNGxi5JlxhLv17YjQjmgHBcVJmtlR4MdoufhbiAWioSGLFJXe Z6oCI8X8zrZGkgbI0+z0C+J9Xc+AosYjhbfBcZb8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2403777AbfGRTXi (ORCPT ); Thu, 18 Jul 2019 15:23:38 -0400 Received: from mail.kernel.org ([198.145.29.99]:37006 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390241AbfGRTXh (ORCPT ); Thu, 18 Jul 2019 15:23:37 -0400 Received: from tzanussi-mobl (c-98-220-238-81.hsd1.il.comcast.net [98.220.238.81]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E13822173B; Thu, 18 Jul 2019 19:23:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1563477816; bh=cl4chmJfGrtFs/C/yZpzQPOkVkMTOGa0056pV1iOO1k=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=0/hb4gbeIlZ19nkcWheImfrWFozPP01Talol7g7GAt/zpJ0Np79KRVq+ihUbIHdxo oiwyLZJgDHSEPCyXPDAmNdI9PDfuUfNoNpJZKaK56S7UDDu3jPgwbC0b9YsOabU6+k KBydBU1KWFzO9jTL6NCCL200h+ZMCe6SJfvQQJdE= Message-ID: <1563477813.12300.2.camel@kernel.org> Subject: Re: [patch V2 1/1] Kconfig: Introduce CONFIG_PREEMPT_RT From: Tom Zanussi To: Thomas Gleixner , Linus Torvalds Cc: LKML , Andrew Morton , Greg Kroah-Hartman , Ingo Molnar , 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 , Gratian Crisan Date: Thu, 18 Jul 2019 14:23:33 -0500 In-Reply-To: References: <20190715150402.798499167@linutronix.de> <20190715150601.205143057@linutronix.de> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.26.1-1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Wed, 2019-07-17 at 22:01 +0200, 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 > Acked-by: Paul E. McKenney > Acked-by: Steven Rostedt (VMware) > Acked-by: Clark Williams > Acked-by: Daniel Bristot de Oliveira > Acked-by: Frederic Weisbecker > Acked-by: Ingo Molnar > Acked-by: Peter Zijlstra (Intel) > Acked-by: Marc Zyngier > Acked-by: Daniel Wagner > --- As one of the stable-rt maintainers, I'd obviously be very happy to see this finally go in. :-) And will be happy to do what I can to help with the remaining 311... Acked-by: Tom Zanussi > V2: Fix typos in help text, collect acks > --- > 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 > + 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