From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1754809AbcFTSlu (ORCPT <rfc822;w@1wt.eu>);
	Mon, 20 Jun 2016 14:41:50 -0400
Received: from merlin.infradead.org ([205.233.59.134]:43840 "EHLO
	merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1751428AbcFTSli (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Mon, 20 Jun 2016 14:41:38 -0400
Date: Mon, 20 Jun 2016 16:30:03 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Jiri Olsa <jolsa@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>, lkml <linux-kernel@vger.kernel.org>,
        James Hartsock <hartsjc@redhat.com>, Rik van Riel <riel@redhat.com>,
        Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
        Kirill Tkhai <ktkhai@parallels.com>
Subject: Re: [PATCH 2/4] sched/fair: Introduce idle enter/exit balance
 callbacks
Message-ID: <20160620143003.GI30154@twins.programming.kicks-ass.net>
References: <1466424914-8981-1-git-send-email-jolsa@kernel.org>
 <1466424914-8981-3-git-send-email-jolsa@kernel.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1466424914-8981-3-git-send-email-jolsa@kernel.org>
User-Agent: Mutt/1.5.23.1 (2014-03-12)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Mon, Jun 20, 2016 at 02:15:12PM +0200, Jiri Olsa wrote:
> Introducing idle enter/exit balance callbacks to keep
> balance.idle_cpus_mask cpumask of current idle cpus
> in system.
> 
> It's used only when REBALANCE_AFFINITY feature is
> switched on. The code functionality of this feature
> is introduced in following patch.
> 
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
>  kernel/sched/fair.c  | 32 ++++++++++++++++++++++++++++++++
>  kernel/sched/idle.c  |  2 ++
>  kernel/sched/sched.h |  3 +++
>  3 files changed, 37 insertions(+)
> 
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index f19c9435c64d..78c4127f2f3a 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -7802,6 +7802,37 @@ static inline int on_null_domain(struct rq *rq)
>  	return unlikely(!rcu_dereference_sched(rq->sd));
>  }
>  
> +static struct {
> +	cpumask_var_t	idle_cpus_mask;
> +	atomic_t	nr_cpus;
> +} balance ____cacheline_aligned;

How is this different from the nohz idle cpu mask?