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client-ip=165.204.84.17; helo=SATLEXMB04.amd.com; pr=C Received: from SATLEXMB04.amd.com (165.204.84.17) by BN1PEPF00006000.mail.protection.outlook.com (10.167.243.232) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.20.8534.20 via Frontend Transport; Thu, 13 Mar 2025 17:24:09 +0000 Received: from [172.31.188.187] (10.180.168.240) by SATLEXMB04.amd.com (10.181.40.145) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.39; Thu, 13 Mar 2025 12:24:03 -0500 Message-ID: Date: Thu, 13 Mar 2025 22:54:01 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH v15 4/7] sched: Fix runtime accounting w/ split exec & sched contexts To: John Stultz , LKML CC: Joel Fernandes , Qais Yousef , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Valentin Schneider , Steven Rostedt , Ben Segall , Zimuzo Ezeozue , Mel Gorman , Will Deacon , Waiman Long , Boqun Feng , "Paul E. McKenney" , Metin Kaya , Xuewen Yan , Thomas Gleixner , Daniel Lezcano , Suleiman Souhlal , References: <20250312221147.1865364-1-jstultz@google.com> <20250312221147.1865364-5-jstultz@google.com> Content-Language: en-US From: K Prateek Nayak In-Reply-To: <20250312221147.1865364-5-jstultz@google.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: SATLEXMB04.amd.com (10.181.40.145) To SATLEXMB04.amd.com (10.181.40.145) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BN1PEPF00006000:EE_|PH7PR12MB6956:EE_ X-MS-Office365-Filtering-Correlation-Id: de3fb585-f02b-4cb2-b415-08dd6253ddcf X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|36860700013|376014|7416014|82310400026|1800799024|7053199007; X-Microsoft-Antispam-Message-Info: =?utf-8?B?Um96TkMrWXJxcFo3d1R4Q0k4UThYL3VPTjBaTFpMalBJTWNWQnBHOCtZakND?= =?utf-8?B?OVIrOERwWTk0QmFtSHlDbkpaTy9sU3RZZ3lWalhndCtTVExOaXBUd3dJYlZH?= =?utf-8?B?SEVsQUJKRWNueHRLdGZjR3lGUVRHaitXWm1LWkxyWkUwNnVuUUNlMVRlUjdK?= =?utf-8?B?T0U5SzFZQUJhUGxoMWhmVVVPQ3hWKzUvVmREVTFadTVSS2VHOGFEN3k3RjN5?= =?utf-8?B?dVJiYmhWUEtiaXU1SFdlejFhVWNLdW0rOG5iR3RoT0pYQ1N5M3VzbzIxUmJj?= =?utf-8?B?anZPVjB0KzN6c1dKTGRSWmV1R0t1ZkpLSndjUnlJaHdPU1NINFBqeEJXMGlN?= =?utf-8?B?aUd5NkR2Z1pnQno4SnI2NmZHcDQwZEZDZ1JjejRYNHR3QjJkZExjajRnYjd4?= =?utf-8?B?ZWxueGJMS3RvVGZhRWhLeC9aZmY3KzNoSjZMRi83aml1Y0Q3WSsrbnA0Zkk3?= =?utf-8?B?bWNqS3Rua3NFbGZPZDJPWmwzc2JvM004S3VyQXRQbHgrV0RiL1dmeFVienZr?= =?utf-8?B?MDJzN1QyYXhhSU1hRHBKMmFDOHRVTFBPYWlCbXpTeUF2RmpLMnB6VGFoWFlp?= =?utf-8?B?NzNweVlPdFVwNURUeGZTTjc4dGZCYUZVVDJWTWgrRE1jVmxpWGd2UkdYU05B?= =?utf-8?B?ejc1Q3lwOWY2VUVTa2tWa21vVHFXengvNmliN1ZOKzZJa0M0MzRJOVpQcEdD?= =?utf-8?B?UUZhWlZ2NGg5T2pMUjROeS9GZkhrNzhYVWdFOGZJT1JnOUZoUnc4eXRxckQw?= =?utf-8?B?b3A1T1NOUTNkdEswcTJWUW13NHZwWjMvcXNmbElHTkdoYTlpSjVtUE9OY3Bv?= =?utf-8?B?ZnREY0F4OFM5cTc4TWpwVUY0OUJSR1luVnlJQ1hhVUJRVEsyWTcrbk1uQnkr?= =?utf-8?B?MHpzMi9TMytudXU2ZVZOVlB5WEpPNFc0MEI5QjJrWlB6c1lneWpmam82dERs?= =?utf-8?B?M0hHVWdyMnJ0NkVlZ2xCUjdkaWxGWDdVL2FwVUdJUU9GMFNsejZQTHM1ZkM0?= =?utf-8?B?K1dzejlhUjZFUXYyUnNGVG41VlNFaUl4RnkwTmszL3dicmtsMnhCYjFIRkVt?= =?utf-8?B?akVPdExPVXVYNUY3em9zajJka3ZtODZ1L29ZLzU3T1JRRkhteEZ1Y25JQVM5?= =?utf-8?B?U3c5MzNibGFwSzFVZDgwWHlDWFpuUXdaQWZDd25lR3krUGlNazh0NEFYWSsz?= =?utf-8?B?STdpUGszYzZMcE9RWllMSjd3L3JBWWkvNkxtMjJkTmp3MkJ4Z2dtVmxlT2ZJ?= =?utf-8?B?akx0UzlnMlBia01SRGRheGpRRmNWYXZnVDgxQ2JnSTZSQnRnY3JtdWhGNWh0?= =?utf-8?B?cHNKT1lKZW9UazBpUXNKUVJKOEl1SkFMMjFRNXBDb0VBWDRBbmxOeTZkaDlG?= =?utf-8?B?NmdMTWFzZFlzTmRoZDBhOEsxc2tHWHRRNmw1N3poUHRSdVJ5VmNoWmxJOWpx?= =?utf-8?B?enNLQmNoeDd5OHNXWGN6dkdIYWhtZXRnckFwb3drbUZTSnladU5lU2RTVXc0?= =?utf-8?B?WnNwMUxCU3VIVG1vV2JLOFcxL1ZqQVQ0a1BwQTJna0svK04vOXNBSmRUY2E4?= =?utf-8?B?VFlmL0NFYWpZcTNQZ0lFanM1aEZIbDZtT2d6N1RCZC9yTEdwdEh1Lzl3R3F0?= =?utf-8?B?ejFiaHJNajMxcmFOaTFwTExLazVlODJKemExM3lXRXpvc21oZ2FicXhWS3NE?= =?utf-8?B?YzZDVlRjZmttSDJneVZuMGJBa1pIdVNJbjRrei8yWWFvRnpiVXY0bHlPSUpt?= =?utf-8?B?OTRDOEVxbEVuVnJ2bTM0cmhOOE0rUTZmWHI5cEJIQnhtVUhaVnRqeFJqMCt4?= =?utf-8?B?dVRWVVNCMzg1UjB3MGxjcGwxMXpGdnVGeEFvNVBQZE5YMk5uYkZWdVgybXRp?= =?utf-8?B?WDBnR3JtVjVlN0NpM294bnU2aWt0T252Q0g1emNabUFqY1FqMkVFa29KZkx0?= =?utf-8?B?VkNpQ2ljZ29QWXBYYWJiV3Q2RHpnOGdCS3AzTHV0UUZ4dW4weWU3Qkt6OXRH?= =?utf-8?B?NGx6cVBtUVpBPT0=?= X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:SATLEXMB04.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(36860700013)(376014)(7416014)(82310400026)(1800799024)(7053199007);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 13 Mar 2025 17:24:09.9194 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: de3fb585-f02b-4cb2-b415-08dd6253ddcf X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: BN1PEPF00006000.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH7PR12MB6956 Hello John, On 3/13/2025 3:41 AM, John Stultz wrote: > The idea here is we want to charge the scheduler-context task's > vruntime but charge the execution-context task's sum_exec_runtime. > > This way cputime accounting goes against the task actually running > but vruntime accounting goes against the rq->donor task so we get > proper fairness. > > Cc: Joel Fernandes > Cc: Qais Yousef > Cc: Ingo Molnar > Cc: Peter Zijlstra > Cc: Juri Lelli > Cc: Vincent Guittot > Cc: Dietmar Eggemann > Cc: Valentin Schneider > Cc: Steven Rostedt > Cc: Ben Segall > Cc: Zimuzo Ezeozue > Cc: Mel Gorman > Cc: Will Deacon > Cc: Waiman Long > Cc: Boqun Feng > Cc: "Paul E. McKenney" > Cc: Metin Kaya > Cc: Xuewen Yan > Cc: K Prateek Nayak > Cc: Thomas Gleixner > Cc: Daniel Lezcano > Cc: Suleiman Souhlal > Cc: kernel-team@android.com > Signed-off-by: John Stultz > --- > kernel/sched/fair.c | 21 ++++++++++++++++----- > 1 file changed, 16 insertions(+), 5 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index c798d27952431..f8ad3a44b3771 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -1129,22 +1129,33 @@ static void update_tg_load_avg(struct cfs_rq *cfs_rq) > } > #endif /* CONFIG_SMP */ > > -static s64 update_curr_se(struct rq *rq, struct sched_entity *curr) > +static s64 update_curr_se(struct rq *rq, struct sched_entity *se) > { > u64 now = rq_clock_task(rq); > s64 delta_exec; > > - delta_exec = now - curr->exec_start; > + delta_exec = now - se->exec_start; > if (unlikely(delta_exec <= 0)) > return delta_exec; > > - curr->exec_start = now; > - curr->sum_exec_runtime += delta_exec; > + se->exec_start = now; > + if (entity_is_task(se)) { > + struct task_struct *running = rq->curr; > + /* > + * If se is a task, we account the time against the running > + * task, as w/ proxy-exec they may not be the same. > + */ > + running->se.exec_start = now; > + running->se.sum_exec_runtime += delta_exec; > + } else { > + /* If not task, account the time against se */ > + se->sum_exec_runtime += delta_exec; > + } > > if (schedstat_enabled()) { > struct sched_statistics *stats; > > - stats = __schedstats_from_se(curr); > + stats = __schedstats_from_se(se); > __schedstat_set(stats->exec_max, > max(delta_exec, stats->exec_max)); So I'm slightly confused here - For the case of proxy where entity_is_task(), we charge the delta_exec to the running task's se but then we go ahead and update the exec_max against the stats of the donor's se? That seems odd. Could we just replace the se with &rq->curr->se if entity_is_task() returns true and keep the rest as is? The calculations will be same as what it is above (except for the stats bit) and you'll not require updating "exec_start" for both current task and proxy's se. Thoughts? > } -- Thanks and Regards, Prateek