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=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,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 03898C433DF for ; Mon, 13 Jul 2020 12:55:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C6191206F0 for ; Mon, 13 Jul 2020 12:55:54 +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="jz8sMEjN" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729662AbgGMMzx (ORCPT ); Mon, 13 Jul 2020 08:55:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42110 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726586AbgGMMzx (ORCPT ); Mon, 13 Jul 2020 08:55:53 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0D84CC061755 for ; Mon, 13 Jul 2020 05:55:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.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; bh=Bgjmm0RTwkjol3u3Vm3ArdMHTSLlmvv1aOs6GxS+xr4=; b=jz8sMEjNED4cY6W4gU0jsBwP88 glS/1dqvwaIuZB19kJd+HQ4CioMubFAhYLuJ8rNVR/EfgCHtQtWWUyfIIDZ0/vxfi17jWpTMLCPES OQfPJTN07rV3lBuI9P3V1IhTZw/MLJ62WF95PDPGhk5ytvpoAZgTyu4wEUPU6j5/jywpy3nVPI+q6 GtCe+HexwdKZDggYx4JXjwfeUgCwl1J+0qbxPd7McuwGShoNcqv5zDgE/zHJvloOkZWEWlUrItzbz vb9+z2XAIxc1Z5R3OlyRbcKOJ1Ohr4e4cPxxcHtKS8atoMi6bjLXxEiQ0zk5hGvnSWGaYN2Rt+3DL 8z14O8gQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1juxzm-00087v-VW; Mon, 13 Jul 2020 12:55:47 +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 1AAF9303A02; Mon, 13 Jul 2020 14:55:43 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id CFCD120D27C74; Mon, 13 Jul 2020 14:55:43 +0200 (CEST) Date: Mon, 13 Jul 2020 14:55:43 +0200 From: Peter Zijlstra To: Valentin Schneider Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, morten.rasmussen@arm.com Subject: Re: [PATCH v3 7/7] sched/topology: Use prebuilt SD flag degeneration mask Message-ID: <20200713125543.GJ10769@hirez.programming.kicks-ass.net> References: <20200701190656.10126-1-valentin.schneider@arm.com> <20200701190656.10126-8-valentin.schneider@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200701190656.10126-8-valentin.schneider@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 01, 2020 at 08:06:55PM +0100, Valentin Schneider wrote: > Leverage SD_DEGENERATE_GROUPS_MASK in sd_degenerate() and > sd_degenerate_parent(). > > Note that this changes sd_degenerate() somewhat: I'm using the negation of > SD_DEGENERATE_GROUPS_MASK as the mask of flags not requiring groups, which > is equivalent to: > > SD_WAKE_AFFINE | SD_SERIALIZE | SD_NUMA > > whereas the current mask for that is simply > > SD_WAKE_AFFINE > > I played with a few toy NUMA topologies on QEMU and couldn't cause a > different degeneration than what mainline does currently. If that is deemed > too risky, we can go back to using SD_WAKE_AFFINE explicitly. Arguably SD_SERIALIZE needs groups, note how we're only having that effective for machines with at least 2 nodes. It's a bit shit how we end up there, but IIRC that's what it ends up as. SD_NUMA is descriptive, and not marking a group as degenerates because it has SD_NUMA seems a bit silly. But then, it would be the top domain and would survive anyway?