From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753219AbcEYHuV (ORCPT ); Wed, 25 May 2016 03:50:21 -0400 Received: from mga04.intel.com ([192.55.52.120]:12526 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752293AbcEYHuU (ORCPT ); Wed, 25 May 2016 03:50:20 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.26,363,1459839600"; d="scan'208";a="984241990" Date: Wed, 25 May 2016 07:52:49 +0800 From: Yuyang Du To: Morten Rasmussen Cc: peterz@infradead.org, mingo@redhat.com, dietmar.eggemann@arm.com, vincent.guittot@linaro.org, mgalbraith@suse.de, linux-kernel@vger.kernel.org Subject: Re: [PATCH 07/16] sched: Make SD_BALANCE_WAKE a topology flag Message-ID: <20160524235249.GH18670@intel.com> References: <1464001138-25063-1-git-send-email-morten.rasmussen@arm.com> <1464001138-25063-8-git-send-email-morten.rasmussen@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1464001138-25063-8-git-send-email-morten.rasmussen@arm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 23, 2016 at 11:58:49AM +0100, Morten Rasmussen wrote: > For systems with the SD_ASYM_CPUCAPACITY flag set on higher level in the > sched_domain hierarchy we need a way to enable wake-up balancing for the > lower levels as well as we may want to balance tasks that don't fit the > capacity of the previous cpu. > > We have the option of introducing a new topology flag to express this > requirement, or let the existing SD_BALANCE_WAKE flag be set by the > architecture as a topology flag. The former means introducing yet > another flag, the latter breaks the current meaning of topology flags. > None of the options are really desirable. I'd propose to replace SD_WAKE_AFFINE with SD_BALANCE_WAKE. And the SD_WAKE_AFFINE semantic is simply "waker allowed": waker_allowed = cpumask_test_cpu(cpu, tsk_cpus_allowed(p)); This can be implemented without current functionality change. >>From there, the choice between waker and wakee, and fast path select_idle_sibling() and the rest slow path should be reworked, which I am thinking about.