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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 5AEA7C433DF for ; Fri, 9 Oct 2020 11:42:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EFE0921789 for ; Fri, 9 Oct 2020 11:42:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="rV/73fj+" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388191AbgJILmg (ORCPT ); Fri, 9 Oct 2020 07:42:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55696 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731908AbgJILmc (ORCPT ); Fri, 9 Oct 2020 07:42:32 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2FE26C0613D2; Fri, 9 Oct 2020 04:42:32 -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=RcamcxMM04cAFejMyuerox9iFyryVbfUvRjDUF6K+9E=; b=rV/73fj+p5/T3eYZYDymfCt5SP EGKltICU3UJgzJot3PlAdj3AbR+gk5Fu9ALysyRXUjXz1Zz9lkn1oy67SKaaUgwwoVb88K0SV7Bsh FqvpyAsddMNfO/uaOg5us46reQYdxoaw4V+Z56lK4XPhIyX56i/ukTdBdBh7EvlM1NHScvtTABqpo znLocfz8vCn//mXjXUAto9jooaYcx8KnZYLrEJUFEaEecZwQ67rFlXOnv+PAUplGmjypRkBw6zEJZ e0yFWzBMPGuSmWRNegKe32QuMxAhYnEeqk1p16v+xTaCE9aMZ0ypzDv+kqeYOcTeyxLPICzHhq0Jp 54eNIb9Q==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kQqmw-0003xU-UC; Fri, 09 Oct 2020 11:42:19 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id E04B9300455; Fri, 9 Oct 2020 13:42:16 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 8A6E02B08A0EA; Fri, 9 Oct 2020 13:42:16 +0200 (CEST) Date: Fri, 9 Oct 2020 13:42:16 +0200 From: Peter Zijlstra To: Michal Hocko Cc: Thomas Gleixner , Frederic Weisbecker , LKML , Mel Gorman , Ingo Molnar , Richard Henderson , Ivan Kokshaysky , Matt Turner , linux-alpha@vger.kernel.org, Brian Cain , linux-hexagon@vger.kernel.org, Geert Uytterhoeven , linux-m68k@lists.linux-m68k.org, Jeff Dike , Richard Weinberger , Anton Ivanov , linux-um@lists.infradead.org Subject: Re: [RFC PATCH] kernel: allow to configure PREEMPT_NONE, PREEMPT_VOLUNTARY on kernel command line Message-ID: <20201009114216.GM2628@hirez.programming.kicks-ass.net> References: <20201007120401.11200-1-mhocko@kernel.org> <20201009091218.GF4967@dhcp22.suse.cz> <20201009094245.GG2628@hirez.programming.kicks-ass.net> <20201009101044.GH4967@dhcp22.suse.cz> <20201009101431.GJ2628@hirez.programming.kicks-ass.net> <20201009103730.GJ4967@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201009103730.GJ4967@dhcp22.suse.cz> Precedence: bulk List-ID: X-Mailing-List: linux-m68k@vger.kernel.org On Fri, Oct 09, 2020 at 12:37:30PM +0200, Michal Hocko wrote: > On Fri 09-10-20 12:14:31, Peter Zijlstra wrote: > > On Fri, Oct 09, 2020 at 12:10:44PM +0200, Michal Hocko wrote: > > > On Fri 09-10-20 11:42:45, Peter Zijlstra wrote: > > > > On Fri, Oct 09, 2020 at 11:12:18AM +0200, Michal Hocko wrote: > > > > > Is there any additional feedback? Should I split up the patch and repost > > > > > for inclusion? > > > > > > > > Maybe remove PREEMPT_NONE after that? Since that's then equivalent to > > > > building with VOLUNTARY and booting with preempt=none. > > > > > > So do you mean that I should post an additional patch which does this on > > > top? With a justification that there is one option less to chose from? > > > > Exactly! > > It seems we have to get rid of CONFIG_NO_PREEMPT first > $ git grep ARCH_NO_PREEMPT > arch/Kconfig:config ARCH_NO_PREEMPT > arch/alpha/Kconfig: select ARCH_NO_PREEMPT > arch/hexagon/Kconfig: select ARCH_NO_PREEMPT > arch/m68k/Kconfig: select ARCH_NO_PREEMPT if !COLDFIRE > arch/um/Kconfig: select ARCH_NO_PREEMPT > kernel/Kconfig.preempt: depends on !ARCH_NO_PREEMPT > kernel/Kconfig.preempt: depends on !ARCH_NO_PREEMPT > lib/Kconfig.debug: select PREEMPT_COUNT if !ARCH_NO_PREEMPT > lib/Kconfig.debug: depends on !ARCH_NO_PREEMPT > > Is there anybody working on that. Is this even possible? I can see it > has been added by 87a4c375995e ("kconfig: include kernel/Kconfig.preempt > from init/Kconfig") but this looks more like a mechanical change and it > has defined ARCH_NO_PREEMPT all arches which haven't included > Kconfig.preempt. But is there any reason why those cannot support > preemption for some reason? Cc respective maintainer (the email thread > starts http://lkml.kernel.org/r/20201007120401.11200-1-mhocko@kernel.org I suspect we can drop ARCH_NO_PREEMPT from VOLUNTARY, IIRC there's no arch dependency there. PREEMPT itself obviously needs arch help.