Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Wed, 1 Sep 2021 21:22:06 -0400
From:   Daniel Jordan <daniel.m.jordan@oracle.com>
To:     Josh Don <joshdon@google.com>
Cc:     Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Juri Lelli <juri.lelli@redhat.com>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
        Daniel Bristot de Oliveira <bristot@redhat.com>,
        Paul Turner <pjt@google.com>,
        Oleg Rombakh <olegrom@google.com>,
        Viresh Kumar <viresh.kumar@linaro.org>,
        Steve Sistare <steven.sistare@oracle.com>,
        Tejun Heo <tj@kernel.org>, Rik van Riel <riel@surriel.com>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 1/4] sched: cgroup SCHED_IDLE support
Message-ID: <20210902012206.cm6flytlp63c2h5v@oracle.com>
References: <20210820010403.946838-1-joshdon@google.com>
 <20210820010403.946838-2-joshdon@google.com>
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20210820010403.946838-2-joshdon@google.com>
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?cxAEwdGpbGGq6jmP+V8cwpW8E9N9GIUZIQUT9XS2s5Ehn6yd//sM+AYyWCxC?=
 =?us-ascii?Q?Tk3RL3cXY0ZGbZvgMx2RKnrunnb9hjdBOkTOkcnmkY4EOrulQELbyljYwMZ5?=
 =?us-ascii?Q?anxRImEnW9MR41SurQqzzb0/7h2PKTVwvOu2lsNgyxKUSkLWWelqyVG/ldOk?=
 =?us-ascii?Q?GaRDUlx/cXzsLpRQk1sD075rKXYrzg1+5ZElx86TBcsh9ThJSfg+hQV/XdKw?=
 =?us-ascii?Q?zIPPzjHX2FJzTfa3S9owULW71s+nrgM0Gvqb9+eWHnwT1iKbXcPqjw91W6Qx?=
 =?us-ascii?Q?Cc8OYUQ+zVf2+giDfqSAwwDRkXkt730jchODaVbEZEYPTjlhOC5qKGEW87Z+?=
 =?us-ascii?Q?ES2RsGuI7Kf86ZPXGwp36EwvHC4CrD60V8YA2rNmQBdP/ZGiT0Pv2pM4nwZE?=
 =?us-ascii?Q?DWb+WQ6ZlQLFuZ4A5e24IzQrNzQOO1DzrR9RX2XQAfXsjhQplEeA00QMXuQr?=
 =?us-ascii?Q?Tl/4f476wO6gJCs/DAXK1huqDd8jkR0e1aMPFUboYOZDNOSnKWdFh5+oomx4?=
 =?us-ascii?Q?wplD/gmVwwlwzYFIjw66dDKFP2jR8hTASJCBLv0Ct1mIm+SqWL32+NElsD13?=
 =?us-ascii?Q?FhyqLeFNoIsGUYIkkEbExc1kR56VzqtMCtoBjvRhdd2SBQP8ipZexU8W3qJm?=
 =?us-ascii?Q?THTs2AZHsxBTRyYa1V1Lq8F0J3VC3rHKJtYx0AH5pcLfe8bQWDuZg88AuQIf?=
 =?us-ascii?Q?lxsqohII9nzF6JAUsjzgMcIJVVQ/EYAJmJOLeV4sm/IrUbER2fj+jfuOcq2b?=
 =?us-ascii?Q?qQTkCHo6BXX2VLE602qFLfgohC9drNLWb+1deQ8BODieRQa4ueihukSVcuAR?=
 =?us-ascii?Q?f12rZWzIyO8szpCskZDNkqS3Fr5QPlFVNEfTHh07PRtKjmb86YDsd406Kj3N?=
 =?us-ascii?Q?haa/GnrfPB0HQ3OUCvUl2GztEkttOwt7b3YVEN3XkkTECLJ39+MBAZI5aZ/w?=
 =?us-ascii?Q?qnMzIVZ5macFQEIO+MY1h7UU2FnhMUG/VA0TFyZpvPrL4/wKd7IfM/PKqhv0?=
 =?us-ascii?Q?OW0VVwLgsRFucmX2XuFKt13HN4QoH2rx6JJVdR76ToxYw9r4wr3daXIzrNSd?=
 =?us-ascii?Q?FC0SvomUDHurPhNJMyP+u0k5uGQL4I82w3Aw5eqwKkoH7vb2MrqjOqSkK5go?=
 =?us-ascii?Q?F1ULK1ia/2Ga+6b8YijbSQztTPbuU4QZ9WHodBpkCpvAnuhJcPQ9wm6e0eJA?=
 =?us-ascii?Q?eyU0VZ3QWkDIWUBIduBci6pZNSlGUqsx9FAzb6s1tOwfp4Xui0uWcLc5lRIF?=
 =?us-ascii?Q?3i+odB8ZuJHZCYFyoZc7YvFtu68v+2xVhAfQYStSCxWkYGF1ncCrWPcFoIFI?=
 =?us-ascii?Q?uxlRt4Naz0HCMcx4CwwzhLG6?=
X-OriginatorOrg: oracle.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 840d10cf-9bfb-48e3-cfee-08d96db01695
X-MS-Exchange-CrossTenant-AuthSource: BYAPR10MB2966.namprd10.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 02 Sep 2021 01:22:11.3692
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: mmtu6Ddp7QvqZUPjm3jFBjXCB5BaeNhZPMg6D5ZKxDVuh/+AD0gBOv9VT6Y0UhjaOJ2scinCkifhCn8N1xBObGUhX1T2fX/iVCx5vDjynQM=
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR10MB3192
X-Proofpoint-Virus-Version: vendor=nai engine=6300 definitions=10094 signatures=668682
X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 bulkscore=0 malwarescore=0
 mlxlogscore=917 spamscore=0 phishscore=0 mlxscore=0 suspectscore=0
 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2108310000
 definitions=main-2109020006
X-Proofpoint-GUID: u21DTU6KNPYQTp-So-591rtJhIabaTq2
X-Proofpoint-ORIG-GUID: u21DTU6KNPYQTp-So-591rtJhIabaTq2
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Thu, Aug 19, 2021 at 06:04:00PM -0700, Josh Don wrote:
> +static int se_is_idle(struct sched_entity *se)
> +{
> +	return 0;
> +}

I'm thinking !FAIR_GROUP_SCHED is a rare thing to behold?  So not a big
deal, but I think this wants to be

        return task_has_idle_policy(task_of(se));

so buddies aren't set for SCHED_IDLE.

>  static void set_last_buddy(struct sched_entity *se)
>  {
> -	if (entity_is_task(se) && unlikely(task_has_idle_policy(task_of(se))))
> -		return;
> -
>  	for_each_sched_entity(se) {
>  		if (SCHED_WARN_ON(!se->on_rq))
>  			return;
> +		if (se_is_idle(se))
> +			return;
>  		cfs_rq_of(se)->last = se;
>  	}
>  }
>  
>  static void set_next_buddy(struct sched_entity *se)
>  {
> -	if (entity_is_task(se) && unlikely(task_has_idle_policy(task_of(se))))
> -		return;
> -
>  	for_each_sched_entity(se) {
>  		if (SCHED_WARN_ON(!se->on_rq))
>  			return;
> +		if (se_is_idle(se))
> +			return;
>  		cfs_rq_of(se)->next = se;
>  	}
>  }