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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 1FBEBC32771 for ; Mon, 6 Jan 2020 08:10:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E728720848 for ; Mon, 6 Jan 2020 08:10:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="ZUDeLbmS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726180AbgAFIKb (ORCPT ); Mon, 6 Jan 2020 03:10:31 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:57478 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725446AbgAFIKa (ORCPT ); Mon, 6 Jan 2020 03:10:30 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=4jQT2MzQnGVbRqu0zEK79SsXrd8bqafhR3CZKOJDJAI=; b=ZUDeLbmSrGs+4SbT7pm8/4nX8 tDqFDyrJfAWLbNTFH8krQ/jD9CmZo00y/8QCaZP/ZD0ZF0J74oLl6njQxiLOSuXqbifp2mteZIGXj Kv48FYjP11u/tXXxudiu2rB3gBeZb24sS/qIjcM0/Hm6r+qSKpGnI+ABWjvnUJSoElxkky5fLM35H pQGJvDdOd6JNvrZhY/d9wRPC5LwSeEfREX3urIJGZlAVhpTzX2OTUqKnYwEZJ66FhsWaexuXiaK1a kTzHNM5qH4k0+kw6bvh+llV0aCM3NNITchFIeu4CsP76UfMNAxMRZC2Uexhda+koZZrKFhNq/l46d A4PJKUhpw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1ioNSx-0008Gk-9a; Mon, 06 Jan 2020 08:10:23 +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 A8799304124; Mon, 6 Jan 2020 09:08:48 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 5F1612B508237; Mon, 6 Jan 2020 09:10:20 +0100 (CET) Date: Mon, 6 Jan 2020 09:10:20 +0100 From: Peter Zijlstra To: Valentin Schneider Cc: linux-kernel@vger.kernel.org, mingo@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, Juri Lelli , Steven Rostedt Subject: Re: [RFC PATCH 0/7] sched: Streamline select_task_rq() & select_task_rq_fair() Message-ID: <20200106081020.GL2844@hirez.programming.kicks-ass.net> References: <20191211164401.5013-1-valentin.schneider@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191211164401.5013-1-valentin.schneider@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 11, 2019 at 04:43:54PM +0000, Valentin Schneider wrote: > Discussion points > ================= > > The use of SD_LOAD_BALANCE forced me to do a few ugly things. > > Patch 5 is only required because the domain walk in select_task_rq_fair() > is ceiled by the presence of SD_LOAD_BALANCE. Thing is (I also ramble about > this in the changelog of patch 7) AFAIK this flag is set unconditionally in > sd_init() and the only way to clear it is via the sched_domain sysctl, > which is a SCHED_DEBUG interface. I haven't found anything with cpusets > that would clear it; AFAICT cpusets can end up attaching the NULL domain to > some CPUs (with sched_load_balance=0) but that's as far as this goes: I can't find it in a hurry, but cpusets should really be able to build stuff without LOAD_BALANCe on, otherwise it is broken. /me digs a little into the code and finds that. no, you're right. What cpusets does is create non-overlapping domain trees for each parition. Which avoids the need to clear that flag. Hmmm.. if we double check all that, I don't suppose there is anything against simply removing that flag. Less is more etc..