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=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_NEOMUTT 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 8D32AC282C8 for ; Mon, 28 Jan 2019 17:02:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 67F7D21741 for ; Mon, 28 Jan 2019 17:02:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733080AbfA1QOb (ORCPT ); Mon, 28 Jan 2019 11:14:31 -0500 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:48296 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732949AbfA1QO1 (ORCPT ); Mon, 28 Jan 2019 11:14:27 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9C6F380D; Mon, 28 Jan 2019 08:14:26 -0800 (PST) Received: from queper01-lin (queper01-lin.cambridge.arm.com [10.1.195.48]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 375713F59C; Mon, 28 Jan 2019 08:14:22 -0800 (PST) Date: Mon, 28 Jan 2019 16:14:17 +0000 From: Quentin Perret To: Sasha Levin Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Peter Zijlstra , Linus Torvalds , Mike Galbraith , Thomas Gleixner , adharmap@codeaurora.org, chris.redpath@arm.com, currojerez@riseup.net, dietmar.eggemann@arm.com, edubezval@gmail.com, gregkh@linuxfoundation.org, javi.merino@kernel.org, joel@joelfernandes.org, juri.lelli@redhat.com, patrick.bellasi@arm.com, pkondeti@codeaurora.org, rjw@rjwysocki.net, skannan@codeaurora.org, smuckle@google.com, srinivas.pandruvada@linux.intel.com, thara.gopinath@linaro.org, tkjos@google.com, valentin.schneider@arm.com, vincent.guittot@linaro.org, viresh.kumar@linaro.org, Ingo Molnar Subject: Re: [PATCH AUTOSEL 4.20 163/304] sched/topology: Add lowest CPU asymmetry sched_domain level pointer Message-ID: <20190128161415.4r4b2gq54o6qdrxa@queper01-lin> References: <20190128154341.47195-1-sashal@kernel.org> <20190128154341.47195-163-sashal@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190128154341.47195-163-sashal@kernel.org> User-Agent: NeoMutt/20171215 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Sasha, On Monday 28 Jan 2019 at 10:41:20 (-0500), Sasha Levin wrote: > From: Quentin Perret > > [ Upstream commit 011b27bb5d3139e8b5fe9ceff1fc7f6dc3145071 ] > > Add another member to the family of per-cpu sched_domain shortcut > pointers. This one, sd_asym_cpucapacity, points to the lowest level > at which the SD_ASYM_CPUCAPACITY flag is set. While at it, rename the > sd_asym shortcut to sd_asym_packing to avoid confusions. > > Generally speaking, the largest opportunity to save energy via > scheduling comes from a smarter exploitation of heterogeneous platforms > (i.e. big.LITTLE). Consequently, the sd_asym_cpucapacity shortcut will > be used at first as the lowest domain where Energy-Aware Scheduling > (EAS) should be applied. For example, it is possible to apply EAS within > a socket on a multi-socket system, as long as each socket has an > asymmetric topology. Energy-aware cross-sockets wake-up balancing will > only happen when the system is over-utilized, or this_cpu and prev_cpu > are in different sockets. Although I'm not really confident about the process for those AUTOSEL patches, I think this one alone won't help anybody without the other ~10 EAS patches. And I assume you definitely don't want to mark those as stable, so I'm not sure if this one is a good candidate either. On a side note, the best description I could find of AUTOSEL with a 5 min Google search is this: https://lwn.net/Articles/750057/ Do you have any pointers to a doc where I can read up about AUTOSEL ? Thanks, Quentin