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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,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 E7A27C47082 for ; Tue, 8 Jun 2021 14:05:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C600F61363 for ; Tue, 8 Jun 2021 14:05:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233156AbhFHOHA (ORCPT ); Tue, 8 Jun 2021 10:07:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54130 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233129AbhFHOG5 (ORCPT ); Tue, 8 Jun 2021 10:06:57 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1C531C061574 for ; Tue, 8 Jun 2021 07:05:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=J43xUH/AHZt4gJaM2xTrRjyhFCkU6scv91z9S7p/g5o=; b=sa7zDG5qeI+XoEULbAJLGTxuG4 OiePmA+AbUCIunerllEvQZR0v7LY32U9S+ivZGB6eBsiYORlutqLhQHLZy+N9DsGSYFa2H5Blx0id vh5d0WfZ8VuvpIsu9kVGj06YH+uZwZFmx+9wvZSvNpaZ6vsRnMXudrv4qvYgEL2uv+9dojiG9Eqhj E6h6t/9mcQM1m8yoQgwd7vADwrGgsZlEqHoqTankerPgnuYg5YomZHJQb6wTAFub2yjm7vmVR+tJm llPh03GREfzc2xFQOzddJyrdyYQq6eqTz0c1ivg95itJxlfskv2ilxbMr2o9HP5J4kZcfECfOyjHQ XJ0C1taA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1lqcLX-00H0AE-QT; Tue, 08 Jun 2021 14:04:49 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 76A9A30018A; Tue, 8 Jun 2021 16:04:47 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 5FAF5201DEF2D; Tue, 8 Jun 2021 16:04:47 +0200 (CEST) Date: Tue, 8 Jun 2021 16:04:47 +0200 From: Peter Zijlstra To: Frederic Weisbecker Cc: Ingo Molnar , LKML Subject: Re: [PATCH 1/2] sched: Add default dynamic preempt mode Kconfig Message-ID: 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 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_*. > help > This option allows to define the preemption model on the kernel > command line parameter and thus override the default preemption > @@ -100,6 +122,22 @@ config PREEMPT_DYNAMIC > Interesting if you want the same pre-built kernel should be used for > both Server and Desktop workloads. > > +# actual preemption model > + > +config PREEMPT_NONE > + bool > + default y if !PREEMPT_DYNAMIC && PREEMPT_TYPE_NONE > + > +config PREEMPT_VOLUNTARY > + bool > + default y if !PREEMPT_DYNAMIC && PREEMPT_TYPE_VOLUNTARY > + > +config PREEMPT > + bool > + default y if !PREEMPT_DYNAMIC && PREEMPT_TYPE_FULL > + select PREEMPTION > + select UNINLINE_SPIN_UNLOCK if !ARCH_INLINE_SPIN_UNLOCK > + > config SCHED_CORE > bool "Core Scheduling for SMT" > default y