From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mp1.migadu.com ([2001:41d0:303:e224::]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) by ms13.migadu.com with LMTPS id cNxXLospeGfe+AAA62LTzQ:P1 (envelope-from ) for ; Fri, 03 Jan 2025 18:16:43 +0000 Received: from aspmx1.migadu.com ([2001:41d0:303:e224::]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) by mp1.migadu.com with LMTPS id cNxXLospeGfe+AAA62LTzQ (envelope-from ) for ; Fri, 03 Jan 2025 19:16:43 +0100 X-Envelope-To: larch@yhetil.org Authentication-Results: aspmx1.migadu.com; dkim=pass header.d=disroot.org header.s=mail header.b=bmdkB1wd; spf=pass (aspmx1.migadu.com: domain of "guix-devel-bounces+larch=yhetil.org@gnu.org" designates 209.51.188.17 as permitted sender) smtp.mailfrom="guix-devel-bounces+larch=yhetil.org@gnu.org"; dmarc=pass (policy=reject) header.from=disroot.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=yhetil.org; s=key1; t=1735928203; h=from:from:sender:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:list-id:list-help: list-unsubscribe:list-subscribe:list-post:dkim-signature; bh=DxZSEtMjeBcV684yX++CZ/gmtV1j9tOIdjVNIVmLl5E=; b=nQD0tJLUMHoZ5AnjuHWDdYA/YBVMG0FdKPCxUl+T2GWJW+xC8/7qaNcz1cgX9oPJjAO/38 s/LWLFvlOocUPDSBZ2GlOp6fjHhx10p14U99UziYxZaOZdl4dgP4GuUUi1QcKGlj12YaHG RcFki1iHNHYn6XQzkzlcHWU7nCJkP+haOhsm99GYH+BJeOoM5Y2wymYsBdB30M8IYatZhH Y3uGWFsdExib1cdX11K3fd0jzfQ9fBAahljSP7BZ4tG+zicto+HsZDtshlHnqMTjnHWepW FGhRO1NRRokTMRqqfeuR8XDfFN5UavgSSv9ZQcLfUzyeimbl+LerhvvArskzTw== ARC-Authentication-Results: i=1; aspmx1.migadu.com; dkim=pass header.d=disroot.org header.s=mail header.b=bmdkB1wd; spf=pass (aspmx1.migadu.com: domain of "guix-devel-bounces+larch=yhetil.org@gnu.org" designates 209.51.188.17 as permitted sender) smtp.mailfrom="guix-devel-bounces+larch=yhetil.org@gnu.org"; dmarc=pass (policy=reject) header.from=disroot.org ARC-Seal: i=1; s=key1; d=yhetil.org; t=1735928203; a=rsa-sha256; cv=none; b=k6XI6TjJoGlwPVAxip2JO+7Jqy7H1gvetylJ8hQH9WMRxIIEMTYd8XcB9XgRmaSjooWZEz 2iIWEqLnnfDSeHVWilVxuKVFPUcrASP01R2gM6BjY9pA22iAYbHOULcsdh/fWY+nUKicOV Nz03ztgqbjLunrNzxXau66vhCl1IE2QKRL4VLaa8G44GRunSPb9MSnKLdWdJIsbE82PiQv GVKuKE5AKrF+xIKivZ1zVwlm6s6eSwCcZQKAGXwq0y0yhZ1wJMZspjuim3EHYpCseuyKhL tu3rsjUCe/Ga27BpJ5pllaJKMMLAEq3HOSZ/uk1Vp1vcJYd+5xAgFZgh/FBrWg== Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by aspmx1.migadu.com (Postfix) with ESMTPS id 36E081A2E3 for ; Fri, 03 Jan 2025 19:16:43 +0100 (CET) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tTmDP-0003GH-JM; Fri, 03 Jan 2025 13:16:07 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tTmDE-0003FS-8N for guix-devel@gnu.org; Fri, 03 Jan 2025 13:16:00 -0500 Received: from layka.disroot.org ([178.21.23.139]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1tTmDB-0007Vp-IZ for guix-devel@gnu.org; Fri, 03 Jan 2025 13:15:55 -0500 Received: from mail01.disroot.lan (localhost [127.0.0.1]) by disroot.org (Postfix) with ESMTP id 8F9C325B56; Fri, 3 Jan 2025 19:15:48 +0100 (CET) X-Virus-Scanned: SPAM Filter at disroot.org Received: from layka.disroot.org ([127.0.0.1]) by localhost (disroot.org [127.0.0.1]) (amavis, port 10024) with ESMTP id XbwKA22uUZP8; Fri, 3 Jan 2025 19:15:44 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=disroot.org; s=mail; t=1735928144; bh=lCvVK7QUsNZmvP2bmlAevShNTVa9HJ2zS8LtZ4GK7e0=; h=Date:Subject:To:References:From:In-Reply-To; b=bmdkB1wd1AlA+a1f+iVQg2Vw39pVWUHqOSinXV9qujJJ+Iq38FLkJA9CDTRFeGIib Q2Q7WP1OVxrhh6HRwo5d2RRVMxY+K79j2I0Z5lqLLWj77y3X4jr9tkY6AShFeIJIsX JoanT0cgq+0NrCKwfzVtY80OqBbaAKjX306XZnYui0m+mmKRSgG/ZManDh2my6l6ba a6NRvIXLmcefLRbLtGrzXKtwTFzwk0MCZKiL0cINVh/jwnRfI30WhcTwyGeydnMJ6S eszKKpYdm413u32VLaErH1gc3dao/n/d+tYAjK0T+bhoU3PZdpbhommT/JU55KkaZo FyLmtzLo/zzOg== Message-ID: <984fd7bf-40e2-4617-89e4-8fd488e47840@disroot.org> Date: Fri, 3 Jan 2025 13:15:42 -0500 MIME-Version: 1.0 Subject: Re: Linux 6.12 new preemption models To: Leo Famulari , guix-devel@gnu.org References: From: kiasoc5 Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=178.21.23.139; envelope-from=kiasoc5@disroot.org; helo=layka.disroot.org X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: guix-devel@gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Development of GNU Guix and the GNU System distribution." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: guix-devel-bounces+larch=yhetil.org@gnu.org Sender: guix-devel-bounces+larch=yhetil.org@gnu.org X-Migadu-Flow: FLOW_IN X-Migadu-Country: US X-Migadu-Scanner: mx12.migadu.com X-Migadu-Spam-Score: -4.27 X-Spam-Score: -4.27 X-Migadu-Queue-Id: 36E081A2E3 X-TUID: CGyVFFCIWf6z On 1/1/25 17:51, Leo Famulari wrote: > FYI, Linux / linux-libre 6.12 introduces a new set of preemption > options: > > ------ > Preemption Model > 1. No Forced Preemption (Server) (PREEMPT_NONE) >> 2. Voluntary Kernel Preemption (Desktop) (PREEMPT_VOLUNTARY) > 3. Preemptible Kernel (Low-Latency Desktop) (PREEMPT) > 4. Fully Preemptible Kernel (Real-Time) (PREEMPT_RT) (NEW) > ------ > > These options trade between kernel throughput and latency. > > PREEMPT_NONE is how the kernels worked before 6.12. > > The trade-off made in PREEMPT_VOLUNTARY is suggested for desktops, so > I'm going to select it for our 6.12 kernel packaging and it will > presumably remain so for future versions as well. > > But if you are building Guix kernels for a busy server or HPC, you > should select PREEMPT_NONE. And you might have use cases for the other > options as well. > > Let me know if you disagree. > > References: > https://cateee.net/lkddb/web-lkddb/PREEMPT_NONE.html > https://cateee.net/lkddb/web-lkddb/PREEMPT_VOLUNTARY.html > https://cateee.net/lkddb/web-lkddb/PREEMPT.html > https://cateee.net/lkddb/web-lkddb/PREEMPT_RT.html > How about PREEMPT_DYNAMIC: https://cateee.net/lkddb/web-lkddb/PREEMPT_DYNAMIC.html This enables changing between PREEMPT_NONE, PREEMPT_VOLUNTARY, and PREEMPT at boot time. Then the only kernel that needs to be compiled separate is PREEMPT_RT.