Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754310AbaKXRPo (ORCPT ); Mon, 24 Nov 2014 12:15:44 -0500 Received: from foss-mx-na.foss.arm.com ([217.140.108.86]:38291 "EHLO foss-mx-na.foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753607AbaKXRPn (ORCPT ); Mon, 24 Nov 2014 12:15:43 -0500 Date: Mon, 24 Nov 2014 17:16:35 +0000 From: Morten Rasmussen To: Vincent Guittot Cc: "peterz@infradead.org" , "mingo@kernel.org" , "linux-kernel@vger.kernel.org" , "preeti@linux.vnet.ibm.com" , "kamalesh@linux.vnet.ibm.com" , "linux-arm-kernel@lists.infradead.org" , "riel@redhat.com" , "efault@gmx.de" , "nicolas.pitre@linaro.org" , "linaro-kernel@lists.linaro.org" Subject: Re: [PATCH v9 08/10] sched: replace capacity_factor by usage Message-ID: <20141124171635.GL23177@e105550-lin.cambridge.arm.com> References: <1415033687-23294-1-git-send-email-vincent.guittot@linaro.org> <1415033687-23294-9-git-send-email-vincent.guittot@linaro.org> <20141121123719.GH23177@e105550-lin.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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, Nov 24, 2014 at 02:41:28PM +0000, Vincent Guittot wrote: > On 21 November 2014 at 13:37, Morten Rasmussen wrote: > > On Mon, Nov 03, 2014 at 04:54:45PM +0000, Vincent Guittot wrote: > > [snip] > > >> */ > >> if (prefer_sibling && sds->local && > >> - sds->local_stat.group_has_free_capacity) > >> - sgs->group_capacity_factor = min(sgs->group_capacity_factor, 1U); > >> + group_has_capacity(env, &sds->local_stat) && > >> + (sgs->sum_nr_running > 1)) { > >> + sgs->group_no_capacity = 1; > >> + sgs->group_type = group_overloaded; > >> + } > > > > I'm still a bit confused about SD_PREFER_SIBLING. What is the flag > > supposed to do and why? > > The goal is to spread tasks across the group even if the the latter is > not overloaded. for SMT level, the goal is to have 1 task per core > before 1 task per HW thread That makes more sense and is in line with how I understand SMT scheduling. So we try to have at least one task per group. Where each group is a domain with SD_PREFER_SIBLING. Anyway, you don't change the prefer-sibling behaviour in this patch set. I was just wondering how it would work for SMT balancing. Thanks, Morten -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/