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=-4.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 D2869C43441 for ; Fri, 23 Nov 2018 16:51:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 51A0320864 for ; Fri, 23 Nov 2018 16:51:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="rFVBZNWr" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 51A0320864 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391230AbeKXDgG (ORCPT ); Fri, 23 Nov 2018 22:36:06 -0500 Received: from mail.kernel.org ([198.145.29.99]:56342 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729195AbeKXDgF (ORCPT ); Fri, 23 Nov 2018 22:36:05 -0500 Received: from localhost (lfbn-ncy-1-241-207.w83-194.abo.wanadoo.fr [83.194.85.207]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 70B8B20672; Fri, 23 Nov 2018 16:51:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1542991866; bh=y+u0IM2C/gDxM/1IIh5emAGQl0ILpUNWvS44IFnlkac=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=rFVBZNWrjb//wit7f/8pu4l6lk5h2JLBgvXgeE5jAR09+vUqkzSM70RUW3OyYGVD5 m7ke2OJUkyR5e1BLohAhiVyh3nkI70SA7Cig+KSByRdC7oeqhB/GjWPvhJBeubYLr2 Mu8/U74u7oUHEu2MYcI5hVWl+/jS7u3C6vzlB5Zo= Date: Fri, 23 Nov 2018 17:51:03 +0100 From: Frederic Weisbecker To: Jan =?iso-8859-1?Q?H=2E_Sch=F6nherr?= Cc: Peter Zijlstra , Ingo Molnar , linux-kernel@vger.kernel.org, Paul Turner , Vincent Guittot , Morten Rasmussen , Tim Chen , Rik van Riel Subject: Re: Task group cleanups and optimizations (was: Re: [RFC 00/60] Coscheduling for Linux) Message-ID: <20181123165102.GB4855@lerouge> References: <20180907214047.26914-1-jschoenh@amazon.de> <20180914111251.GC24106@hirez.programming.kicks-ass.net> <1d86f497-9fef-0b19-50d6-d46ef1c0bffa@amazon.de> <282230fe-b8de-01f9-c19b-6070717ba5f8@amazon.de> <20180917094844.GR24124@hirez.programming.kicks-ass.net> <08b930d9-7ffe-7df3-ab35-e7b58073e489@amazon.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <08b930d9-7ffe-7df3-ab35-e7b58073e489@amazon.de> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 18, 2018 at 03:22:13PM +0200, Jan H. Schönherr wrote: > On 09/17/2018 11:48 AM, Peter Zijlstra wrote: > > Right, so the whole bandwidth thing becomes a pain; the simplest > > solution is to detect the throttle at task-pick time, dequeue and try > > again. But that is indeed quite horrible. > > > > I'm not quite sure how this will play out. > > > > Anyway, if we pull off this flattening feat, then you can no longer use > > the hierarchy for this co-scheduling stuff. > > Yeah. I might be a bit biased towards keeping or at least not fully throwing away > the nesting of CFS runqueues. ;) One detail here, is that hierarchical task group a strong requirement for cosched or could you live with it flattened in the end?