From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTP id E88C2AB4 for ; Mon, 12 May 2014 15:32:45 +0000 (UTC) Received: from collaborate-mta1.arm.com (fw-tnat.austin.arm.com [217.140.110.23]) by smtp1.linuxfoundation.org (Postfix) with ESMTP id BDE5520337 for ; Mon, 12 May 2014 15:32:44 +0000 (UTC) Date: Mon, 12 May 2014 16:32:34 +0100 From: Morten Rasmussen To: ksummit-discuss@lists.linuxfoundation.org Message-ID: <20140512153234.GE23253@e103034-lin> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Cc: Peter Zijlstra , Ingo Molnar Subject: [Ksummit-discuss] Energy-aware Scheduling Workshop List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi, Last year's Energy-Aware Scheduling workshop [1,2] was a good opportunity for interested parties to discuss some of the open issues in this area face to face. While work is still ongoing on many of the topics that were discussed, it might be worth having workshop again this year to follow up, revise the plans if necessary, and discuss topics that were not covered last year. Before submitting a workshop proposal to the Ksummit PC I would like to probe the interest. IMO, it is important that we have scheduler maintainers present. Workshop topic proposals: Test cases Use-cases for high-end phones (which some of us care about) consist of rather complex software stacks which are not suitable for quick patch testing [3]. While we can't avoid testing using the full software stack in the end, it would be useful to have configurable micro-benchmarks for initial testing and to reproduce specific scheduling patterns from the full use-case for debugging purposes. Energy Evaluation A hot topic last year. We need a way to evaluate energy-awareness patches. Work has started on an idle state analysis tool [4], but we are not there yet. Platform Performance/Energy data Currently the kernel has quite limited knowledge about energy costs of the platform where it is running. Without this information it is rather hard to make energy-efficient scheduling decisions. It seems that various energy-saving techniques don't work equally well on all platforms and might even depend on the use-case. Should we give the kernel enough information to construct a simple energy-model to guide decisions? CPU utilization and cpu_power The entity load tracking has given us a much better indication of individual task loadi. However, priority scaling makes it less suitable for low load scenarios [5] where we care more about actual cpu utilization per task when trying to figure out an energy-efficient load balance. Do we need entity utilization tracking as well? Related to this topic is the representation of cpu compute capacity. The current representation, cpu_power, can't deal with heterogeneous systems correctly. Can we come up with a solution that can handle SMT, SMP, and heterogeneous systems? All comments and topic proposals are welcome. Thanks, Morten [1] http://lwn.net/Articles/571414/ [2] http://etherpad.osuosl.org/energy-aware-scheduling-ks-2013 [3] https://lkml.org/lkml/2014/1/7/355 [4] https://lkml.org/lkml/2014/3/24/363 [5] https://lkml.org/lkml/2014/1/7/503