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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C9D52C4332F for ; Wed, 8 Nov 2023 13:58:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233816AbjKHN6V (ORCPT ); Wed, 8 Nov 2023 08:58:21 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41458 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232187AbjKHN6T (ORCPT ); Wed, 8 Nov 2023 08:58:19 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A3CFB1BEF for ; Wed, 8 Nov 2023 05:58:17 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9B92DC433C7; Wed, 8 Nov 2023 13:58:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1699451897; bh=/a9FgUe/BIr5zHWkGLlCKL2qwlPru5dGvvCfOaHtyzo=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=Lyt7u1CJ/ZF3jsfCB0gqngfio8ZQvFpDGerYJS8sdsRoF8vnn1XTJtrz4zY/WXT+D i1+80WpXejxv+DwgjnJmwBdyU8n6VihzENfNWN4Q6z9a7xbzMTPPAAYaqca/Ag71UY /cPxP6kqg5ZqA2wmmd5cPzzbj+bkI6nROqrub9GNFTPq2jkqbowZRYsTtTgIIzyH7S WrGYp5z4pTrIbgaJKUCDJyfsrG3ZEKQLBIQGdjc79rD2IMOSYaBWh/GJwZ7Y+0qKhH W0LBmhU4nXzXecfTwVKuqUk+QVJXWQcbiAfM6J7wxJDburOpQ1FRE+A/Lvbll6/vXd CMcVeEzi39wuw== Message-ID: Date: Wed, 8 Nov 2023 14:58:12 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 6/7] sched/deadline: Deferrable dl server Content-Language: en-US, pt-BR, it-IT To: Peter Zijlstra Cc: Daniel Bristot de Oliveira , Steven Rostedt , Joel Fernandes , Ingo Molnar , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Ben Segall , Mel Gorman , Valentin Schneider , linux-kernel@vger.kernel.org, Luca Abeni , Tommaso Cucinotta , Thomas Gleixner , Vineeth Pillai , Shuah Khan , Phil Auld References: <20231107114732.5dd350ec@gandalf.local.home> <7d1ea71b-5218-4ee0-bc89-f02ee6bd5154@redhat.com> <3e58fad7-7f66-4e48-adcc-0fda9e9d0d07@kernel.org> <20231108124401.GQ8262@noisy.programming.kicks-ass.net> From: Daniel Bristot de Oliveira In-Reply-To: <20231108124401.GQ8262@noisy.programming.kicks-ass.net> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/8/23 13:44, Peter Zijlstra wrote: > Should we rather not cap the runtime, something like so? > > Because the above also causes period drift, which we do not want. like in the example I showed before: - 3/10 reservation (30%). - w=waiting - r=running - s=sleeping - T=throttled - fair server dispatched at 0, starvation from RT. |wwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww|rrrrrrrrrrrrrrrrrrrrrrrrrrrrrr|TTTTTTTTTT[...]TTTTTTTTTTT|rrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr|TTTTTTT |___________________________period 1_________________________________|_________period 2________________________[...]___________|___period 3____________________|[.... internal-period 0---------1---------2---------3---------4---------5---------6--------7--------8---------9----------10.......11.[...]16.........17........18........19........20|[.... < Real-time ---------------------------------------------------------------------+---------------------------------------------------------| | +new period >From "real-world/wall clock" the internal period shift produces the "zerolax" timeline. It runs 3 units of time before the 10's. If one has a mix of DL and FIFO task, and want to enforce a given response time to the fair server, they can reduce the fair server period to achieve that. -- Daniel