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=-6.8 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=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 9FD4EC433DF for ; Fri, 9 Oct 2020 10:10:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2C6712226B for ; Fri, 9 Oct 2020 10:10:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="qMn8RpNt" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387503AbgJIKKr (ORCPT ); Fri, 9 Oct 2020 06:10:47 -0400 Received: from mx2.suse.de ([195.135.220.15]:38404 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726357AbgJIKKq (ORCPT ); Fri, 9 Oct 2020 06:10:46 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1602238245; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=/ov0pV+JB4ZGZv2uDLjVS7nh4hz9wFdZu6KBCZbZ2Jg=; b=qMn8RpNtwWsMeKWX/VdFIczmkvptBUr1BbaGSBAnGBRKE7yRnxNsJwighOhNUaIh7rbrb9 cdDudAZRtDhwUOa1slw4l82M8qNamPdcMYekFOT0H7oWdZ81zPcpFaF7D27weM0xqiIioN 8MFan10Wx23dhbKQuwL2t0td5yzqoIo= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 981D1B048; Fri, 9 Oct 2020 10:10:45 +0000 (UTC) Date: Fri, 9 Oct 2020 12:10:44 +0200 From: Michal Hocko To: Peter Zijlstra Cc: Thomas Gleixner , Frederic Weisbecker , LKML , Mel Gorman , Ingo Molnar Subject: Re: [RFC PATCH] kernel: allow to configure PREEMPT_NONE, PREEMPT_VOLUNTARY on kernel command line Message-ID: <20201009101044.GH4967@dhcp22.suse.cz> References: <20201007120401.11200-1-mhocko@kernel.org> <20201009091218.GF4967@dhcp22.suse.cz> <20201009094245.GG2628@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201009094245.GG2628@hirez.programming.kicks-ass.net> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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? diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt index bf82259cff96..103a5f9e4bcf 100644 --- a/kernel/Kconfig.preempt +++ b/kernel/Kconfig.preempt @@ -2,20 +2,7 @@ choice prompt "Preemption Model" - default PREEMPT_NONE - -config PREEMPT_NONE - bool "No Forced Preemption (Server)" - help - This is the traditional Linux preemption model, geared towards - throughput. It will still provide good latencies most of the - time, but there are no guarantees and occasional longer delays - are possible. - - Select this option if you are building a kernel for a server or - scientific/computation system, or if you want to maximize the - raw processing power of the kernel, irrespective of scheduling - latencies. + default PREEMPT_VOLUNTARY config PREEMPT_VOLUNTARY bool "Voluntary Kernel Preemption (Desktop)" -- Michal Hocko SUSE Labs