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 146A3C433EF for ; Mon, 8 Nov 2021 15:22:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F04B26125F for ; Mon, 8 Nov 2021 15:22:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238983AbhKHPYt convert rfc822-to-8bit (ORCPT ); Mon, 8 Nov 2021 10:24:49 -0500 Received: from foss.arm.com ([217.140.110.172]:51290 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231776AbhKHPYr (ORCPT ); Mon, 8 Nov 2021 10:24:47 -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 B615BD6E; Mon, 8 Nov 2021 07:22:02 -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 E976D3F718; Mon, 8 Nov 2021 07:22:01 -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: <5543627ee8ac5337a74de4b9671240d617273607.camel@gmx.de> References: <20211105104035.3112162-1-valentin.schneider@arm.com> <8735o6uca5.mognet@arm.com> <5543627ee8ac5337a74de4b9671240d617273607.camel@gmx.de> Date: Mon, 08 Nov 2021 15:21:56 +0000 Message-ID: <87zgqesmej.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 08/11/21 13:27, Mike Galbraith wrote: > On Mon, 2021-11-08 at 11:17 +0000, Valentin Schneider wrote: >> On 06/11/21 05:40, Mike Galbraith wrote: >> > >> > 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? > > Um, not sure what that is, but it sounds about right. > >> 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. > > As long as RT depends on EXPERT it'll be a bit annoying regardless. I > just thought it worth mention that what you want now and what RT will > presumably want upon merge completion appear to be mutually exclusive. > Hmm actually I think your approach should work, i.e. have config PREEMPT_DYNAMIC depends on [...] && !PREEMPT_RT rather than config PREEMPT_RT depends on [...] && !PREEMPT_DYNAMIC This essentially gives priority to the preemption model type over the preemption model dynamicness, which I think makes sense. I can fold that in v2. > -Mike