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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 009DCC433F5 for ; Mon, 8 Nov 2021 11:17:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D767E61039 for ; Mon, 8 Nov 2021 11:17:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237126AbhKHLUf convert rfc822-to-8bit (ORCPT ); Mon, 8 Nov 2021 06:20:35 -0500 Received: from foss.arm.com ([217.140.110.172]:49188 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230269AbhKHLUa (ORCPT ); Mon, 8 Nov 2021 06:20:30 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id F05DF2B; Mon, 8 Nov 2021 03:17:45 -0800 (PST) Received: from e113632-lin (e113632-lin.cambridge.arm.com [10.1.196.57]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2FCDD3F800; Mon, 8 Nov 2021 03:17:45 -0800 (PST) From: Valentin Schneider To: Mike Galbraith , linux-kernel@vger.kernel.org Cc: Peter Zijlstra , Ingo Molnar , Frederic Weisbecker Subject: Re: [PATCH] sched: Tweak default dynamic preempt mode selection In-Reply-To: References: <20211105104035.3112162-1-valentin.schneider@arm.com> Date: Mon, 08 Nov 2021 11:17:38 +0000 Message-ID: <8735o6uca5.mognet@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/11/21 05:40, Mike Galbraith wrote: > On Fri, 2021-11-05 at 10:40 +0000, Valentin Schneider wrote: >> Commit c597bfddc9e9 ("sched: Provide Kconfig support for default dynamic >> preempt mode") changed the selectable config names for the preemption >> model. This means a config file must now select >> >>   CONFIG_PREEMPT_BEHAVIOUR=y >> >> rather than >> >>   CONFIG_PREEMPT=y >> >> to get a preemptible kernel. This means all arch config files need to be >> updated - right now arm64 defconfig selects CONFIG_PREEMPT=y but ends up >> with CONFIG_PREEMPT_NONE_BEHAVIOUR=y. >> >> Instead, have CONFIG_*PREEMPT be the selectable configs again, and make >> them select their _BEHAVIOUR equivalent if CONFIG_PREEMPT_DYNAMIC is set. > > > Is there any way to get to PREEMPT_RT in the first selection again as > well? I had created a behavior entry for RT (below) and inverted the > dependency to make it appear in the initial selection again, but that's > clearly not gonna fly. > > Starting with a 5.15 config, to select RT you currently must first > select a model you don't want, then reject PREEMPT_DYNAMIC and you'll > be offered the full menu of models immediately. With your patch added, > that became worse. After rejecting PREEMPT_DYNAMIC, I had to go > through new 5.15+ options before finally being offered the full menu. > Do you mean at the syncconfig step? I've only really played with upstream arm64 / x86 defconfigs and didn't have to fight with any prompts, though yes for x86 the default-y PREEMPT_DYNAMIC makes it a bit annoying to select PREEMPT_RT.