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 S1759966AbdCVRWz (ORCPT <rfc822;w@1wt.eu>);
        Wed, 22 Mar 2017 13:22:55 -0400
Received: from foss.arm.com ([217.140.101.70]:46792 "EHLO foss.arm.com"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S1759691AbdCVRWt (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
        Wed, 22 Mar 2017 13:22:49 -0400
Subject: Re: [PATCH] sched/fair: Fix ftq noise bench regression
To: Vincent Guittot <vincent.guittot@linaro.org>
References: <1489758442-2877-1-git-send-email-vincent.guittot@linaro.org>
 <418a2486-51ec-01f4-2af5-0988bc704a28@arm.com>
 <CAKfTPtDgZSEof9=4Yq8n3Biu6q9o=RdHB178F0RZzkOwNVYjQA@mail.gmail.com>
 <d6e3ade4-2d71-25b1-0477-c4be2756cb75@arm.com>
 <CAKfTPtBjLNyQ3b2qUvOBDvP3VWhMYVCvZ-ndDt65S-WHOwz8UQ@mail.gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        "Huang, Ying" <ying.huang@intel.com>
From: Dietmar Eggemann <dietmar.eggemann@arm.com>
Message-ID: <4d5ec252-9d83-93ef-0d56-27895e8d388d@arm.com>
Date: Wed, 22 Mar 2017 17:22:45 +0000
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101
 Thunderbird/45.7.0
MIME-Version: 1.0
In-Reply-To: <CAKfTPtBjLNyQ3b2qUvOBDvP3VWhMYVCvZ-ndDt65S-WHOwz8UQ@mail.gmail.com>
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 22/03/17 16:55, Vincent Guittot wrote:
> On 22 March 2017 at 17:22, Dietmar Eggemann <dietmar.eggemann@arm.com> wrote:
>> On 22/03/17 09:22, Vincent Guittot wrote:
>>> On 21 March 2017 at 18:46, Dietmar Eggemann <dietmar.eggemann@arm.com> wrote:
>>>> Hi Vincent,
>>>>
>>>> On 17/03/17 13:47, Vincent Guittot wrote:

[...]

>> +static inline bool blocked_update_needed(struct sched_entity *se)
>> +{
>> +       struct cfs_rq *gcfs_rq = group_cfs_rq(se);
> 
> gcfs_rq can't be set before testing that se is not null

Ah correct, but you could set it after the !se check.