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=-11.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 A5BAFC48BD1 for ; Wed, 9 Jun 2021 11:27:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8E8AA61108 for ; Wed, 9 Jun 2021 11:27:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239122AbhFIL3s (ORCPT ); Wed, 9 Jun 2021 07:29:48 -0400 Received: from mail.kernel.org ([198.145.29.99]:42096 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238767AbhFIL3r (ORCPT ); Wed, 9 Jun 2021 07:29:47 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id DB89261364; Wed, 9 Jun 2021 11:27:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1623238073; bh=4WJpXLFKQti9BHVRMa0Ik+rm/Abh/O7WH2yaXGpwWM4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=oElFNQ7EJ3+JXsxOytsR4nnp+4ajArTXZ/mfOlg4QU1jR4PFm/4+K8MvATKR2+3Ne TkwK+s1GyabjgV/uwihYD8eEYxCB9FEy+jPzDRXqg0UPfnzY8HUMko/O8opqe/z+Ru aLmQ8W9vbytnyZ0uwjeMgri4zxLGM4h0Eh4ZEnvIBQnxA6LuMaSSRQ2IvRUYeziFW+ oX8Pp8Vtyw7Av8v5hGLlcd1A3IT0wZQ4CbDXiDe1hTltJMH3xNA4OEs7DAYO12XB3h 5l6t+hRdJPP3KloKCuVrhKIW1F4/GoKMt/DItgRMsAIRoz7hAMdC04BVaJZ9kD7A22 LgiapdfL4fRhw== Date: Wed, 9 Jun 2021 13:27:50 +0200 From: Frederic Weisbecker To: Peter Zijlstra Cc: Ingo Molnar , LKML Subject: Re: [PATCH 1/2] sched: Add default dynamic preempt mode Kconfig Message-ID: <20210609112750.GC104634@lothringen> References: <20210608120442.93587-1-frederic@kernel.org> <20210608120442.93587-2-frederic@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 08, 2021 at 04:04:47PM +0200, Peter Zijlstra wrote: > On Tue, Jun 08, 2021 at 03:55:09PM +0200, Peter Zijlstra wrote: > > Urgh, would something like this work? > > > > --- > > kernel/Kconfig.preempt | 64 ++++++++++++++++++++++++++++++++++++++++---------- > > 1 file changed, 51 insertions(+), 13 deletions(-) > > > > diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt > > index bd7c4147b9a8..43c68a806e4e 100644 > > --- a/kernel/Kconfig.preempt > > +++ b/kernel/Kconfig.preempt > > @@ -1,11 +1,25 @@ > > # SPDX-License-Identifier: GPL-2.0-only > > > > +config PREEMPT_COUNT > > + bool > > + > > +config PREEMPTION > > + bool > > + select PREEMPT_COUNT > > + > > +config PREEMPT_DYNAMIC_OPTION > > + bool > > + help > > + Symbol that gates availablility of PREEMPT_DYNAMIC, selected > > + by preemption models that can be dynamically selected. > > + > > choice > > prompt "Preemption Model" > > + default PREEMPT_TYPE_NONE > > > > +config PREEMPT_TYPE_NONE > > bool "No Forced Preemption (Server)" > > + select PREEMPT_DYNAMIC_OPTION if HAVE_PREEMPT_DYNAMIC > > help > > This is the traditional Linux preemption model, geared towards > > throughput. It will still provide good latencies most of the > > @@ -17,9 +31,10 @@ config PREEMPT_NONE > > raw processing power of the kernel, irrespective of scheduling > > latencies. > > > > +config PREEMPT_TYPE_VOLUNTARY > > bool "Voluntary Kernel Preemption (Desktop)" > > depends on !ARCH_NO_PREEMPT > > + select PREEMPT_DYNAMIC_OPTION if HAVE_PREEMPT_DYNAMIC > > help > > This option reduces the latency of the kernel by adding more > > "explicit preemption points" to the kernel code. These new > > @@ -35,12 +50,10 @@ config PREEMPT_VOLUNTARY > > > > Select this if you are building a kernel for a desktop system. > > > > -config PREEMPT > > +config PREEMPT_TYPE_FULL > > bool "Preemptible Kernel (Low-Latency Desktop)" > > depends on !ARCH_NO_PREEMPT > > + select PREEMPT_DYNAMIC_OPTION if HAVE_PREEMPT_DYNAMIC > > help > > This option reduces the latency of the kernel by making > > all kernel code (that is not executing in a critical section) > > @@ -75,15 +88,24 @@ config PREEMPT_RT > > > > endchoice > > > > +# default model for PREEMPT_DYNAMIC > > > > +config PREEMPT_DYNAMIC_NONE > > + bool > > > > +config PREEMPT_DYNAMIC_VOLUNTARY > > + bool > > + > > +config PREEMPT_DYNAMIC_FULL > > bool > > + > > +config PREEMPT_DYNAMIC > > + bool "Dynamic Preemption Mode" > > + depends on PREEMPT_DYNAMIC_OPTION > > + select PREEMPT > > + select PREEMPT_DYNAMIC_NONE if PREEMPT_TYPE_NONE > > + select PREEMPT_DYNAMIC_VOLUNTARY if PREEMPT_TYPE_VOLUNTARY > > + select PREEMPT_DYNAMIC_FULL if PREEMPT_TYPE_FULL > > Arguably PREEMPT_DYNAMIC_{NONE,VOLUNTARY,FULL} are superfluous and the > default selection can use PREEMPT_TYPE_*. Right, I'll try that. Thanks.