From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from DM5PR21CU001.outbound.protection.outlook.com (mail-centralusazon11011039.outbound.protection.outlook.com [52.101.62.39]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 674093B3C18 for ; Sun, 16 Aug 2026 17:38:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=52.101.62.39 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786901902; cv=fail; b=XY5UvA84hSh8UlfnXBZAGW97/pzbrtC71ILe+zwbfaQpVFHG47CGsXf2uKFubPgbu5js4m9SuJmAsqIfd1NTqWcN+jt01tIHJ5oLXMGSz67MFgQpd2jRLQ2dPKrF6W0UkjzMFFbuDbGoanSI0WfgU5TTQMmitedQEfO16qj5HXk= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786901902; c=relaxed/simple; bh=47sMj7irBGMGqEVztdYvq6VIjQ3aQwMpcvBEHDfH/iQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: Content-Type:MIME-Version; b=fNS0T+esgC7M+DTWtOjhAxwyXc+RBFMc6QuhQbuVoAYteQrPQaf5u0ieoOH+L6PLTqPrQXqkfriZe8C0AGi3fUgSZe5+xv2bvwQ9Ox4HSvsFsIN8bF4pPv8ZRIGD55ho6Q5SPOWTvbwTgXw97WQFIugrLKruIa6p6Ak+HymHeaE= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=nvidia.com; spf=fail smtp.mailfrom=nvidia.com; dkim=pass (2048-bit key) header.d=Nvidia.com header.i=@Nvidia.com header.b=ntjQ5EtM; arc=fail smtp.client-ip=52.101.62.39 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=nvidia.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=nvidia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=Nvidia.com header.i=@Nvidia.com header.b="ntjQ5EtM" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=wPf1318htYap3CJPrXfvXWL9k/TJVPtGrMf2izJLvmXfDEg8HbgwB7bdMDqudFD2dM7LHLphsWsCul3t6FEZYQZLVdu/5lIjWCGDSIlT4t8Z8p8IALmTPfM5OXnrrO7QoyeMuP3MZu0TCyGjcxcejHd4kTC1ArdqXl6DXEy+B2/TDUKmgMhYLJloeyw7mNUpW0fbEYnJY+mvcjhv0yZQqle4Pid7oGD2Vw1OVwWDscGtUOwIxcbGpSDbe2cXQt7jO3zr2rFYrLmKX9n2ajLDkYON1Y1TeixJre9sbC2wyoWji/IXSxjLtdpInwm7DnVKYiEVoLuz10+5SYf6Wt3aIw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=xeMqjXUIphf0kChcbHKZOpif5mE58KPFhl0lKd3PtFs=; b=Am2uMViWdzEAnuauQ5Izk44RfboDHmqpMyLd99+jL++o19ENVRDupkXG6xAP0Wgy9kSthKyDXlMdv+1+9Fdmiom6ZMk3nS8Ncur3SmDgqRK23IrFXR2iRJIEIjymDELAT2j+M4cLvv5WaHUmCSbnexY0CLL1CcjD8I/iMMG66chdYcdAndzNfV796nP0xpRlP0LZoahV+rsZv3jNl54TOeAicQChF3wd0HAcWuI7sLlzmfv2NkLWmr11f27FtkfcU3V59oEEjjH1hOmnEAVasXkU9cDB8bwU8KOgW1INDwmpXrGZqwD5VIINSQOtL/s8abRZV+/XQUAvN1hFqNe+GQ== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=nvidia.com; dmarc=pass action=none header.from=nvidia.com; dkim=pass header.d=nvidia.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=Nvidia.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=xeMqjXUIphf0kChcbHKZOpif5mE58KPFhl0lKd3PtFs=; b=ntjQ5EtMLgMo4Np7ffTi2dMhISJUD+wjlz0QxZESi+Pe30wR9N6W5mhNoSmR/SF0aFPe64TMoQVUnSgfCFwuGGvpH7KY6dunZF3ITRxNbXxetT+lqrJ4WYv/B9OqQ+RjTaOgbJS4FZyu56aH3uEpIWtkq9qDUyK+zjADqypc3BAKS4J2UaP+6WbwrsFFtuJGlLvY5LgFgl5u3A0oimWGQrec9imXqz+HPlSt6k7q45C6e9An4Gn1fZaVHgE+t9oA7cum2eUxJHaPSFeAC9GkVFSTvK6UFQAy9GySVT6+Kqtnfe9vfeG8M+gTg+cSgUKqQQuRgY1wq41XaJJFh9VSJw== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from DM6PR12MB4827.namprd12.prod.outlook.com (2603:10b6:5:1d6::14) by LV0PR12MB999092.namprd12.prod.outlook.com (2603:10b6:408:32e::22) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.315.16; Sun, 16 Aug 2026 17:38:17 +0000 Received: from DM6PR12MB4827.namprd12.prod.outlook.com ([fe80::6261:3040:864b:159c]) by DM6PR12MB4827.namprd12.prod.outlook.com ([fe80::6261:3040:864b:159c%5]) with mapi id 15.21.0315.016; Sun, 16 Aug 2026 17:38:17 +0000 From: Andrea Righi To: Tejun Heo , David Vernet , Changwoo Min , John Stultz Cc: Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , K Prateek Nayak , Christian Loehle , David Dai , Koba Ko , Aiqun Yu , sched-ext@lists.linux.dev, linux-kernel@vger.kernel.org Subject: [PATCH 10/17] sched_ext: Move reject DSQ draining into core Date: Sun, 16 Aug 2026 19:35:08 +0200 Message-ID: <20260816173732.17162-11-arighi@nvidia.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260816173732.17162-1-arighi@nvidia.com> References: <20260816173732.17162-1-arighi@nvidia.com> Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: MI2PEPF00000B76.ITAP293.PROD.OUTLOOK.COM (2603:10a6:298:1::40a) To DM6PR12MB4827.namprd12.prod.outlook.com (2603:10b6:5:1d6::14) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DM6PR12MB4827:EE_|LV0PR12MB999092:EE_ X-MS-Office365-Filtering-Correlation-Id: f0cab190-ecff-43f5-93ea-08defbbd2811 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|23010399003|7416014|366016|376014|1800799024|22082099003|18002099003|10067099003|56012099006|11063799006; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:DM6PR12MB4827.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(23010399003)(7416014)(366016)(376014)(1800799024)(22082099003)(18002099003)(10067099003)(56012099006)(11063799006);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?bEFoafg8LD26llqfYDeT43IerxvUqZ8j24v8MlvAAYirP9egvLaF7tHeU4Pl?= =?us-ascii?Q?3fBqarvc9n+sIQcmgpEQcxGOn2yAXX6cYHqFxpGFQn12SQrR2o9UAfGqj8vY?= =?us-ascii?Q?EYzEvqSVl5mScIvqKbXDHXo/cGT1HqDbTdIxEYX1LBepuAcg3k1IskGyexrB?= =?us-ascii?Q?SjjaO4SPT4uF7+3azL1f89u0v7COF1XU4BaHD/2NyCop9nIWAHtQ58Jy1J52?= =?us-ascii?Q?WKTQXUR81PM6l0nRk8AzlNh5hRkgZnAJa7JOGArgwFHogW6N/b+6Wj86JMI9?= =?us-ascii?Q?T0TfJNJk8ElvBuafbJrhtMEMvflk2dYnw8kIr9cUYqwKfCFxbK2sI2bzexcy?= =?us-ascii?Q?5eF31QybHx0KKgGjRFtQNrPtsq8g9/vrJPmNGf7hIQwnMcR9NEJrQtbXLx3J?= =?us-ascii?Q?JQdy/S4I0GDqgCmbs340/KltIw3iSASBSObRCr5erew5RUplxZE3anqjtAne?= =?us-ascii?Q?UnYc1Fb0PBw7bOeJcVGl66tqwAkqPfc03Odu2h2Sy/duMp7PMtgXzmdVNYGL?= =?us-ascii?Q?n786uznrGPxLq348DdmRM7cWXPsIYK41IPb4aZ3RiEb89ZjmJwCtiHs4oRju?= =?us-ascii?Q?/MXml+8Z1Tb1Mpxw8I3p1cFEMoimoV5p6aUZlXd9zH9m9aaBbyAppCGta367?= =?us-ascii?Q?xMR0+X+m24NheZGlDxFamA+gZa2nqHX1Tj9yKSz5KohVg4j9Tsrqs0RdqI0i?= =?us-ascii?Q?BhNwfDIZvujHaeFi5UgnXI9Gab/7rwjaM6m8GDmV/0Yk3q6kDTyJom88FMYU?= =?us-ascii?Q?radFvboQF3I2/bFePuBN6k5rt1CzuzdGUg97aVgYU0fZ2GkNhU+P1etlvvsL?= =?us-ascii?Q?F9sRP8dQY2ksj5hdYHkrxF4JwWQWqBKtO3jGFsC4nGaOT8CQp342SMCp9jBF?= =?us-ascii?Q?7FT31kXvTFD+KlodbBiiG4bm7dSyBu5rLo0ATWMLXlsMWAJtz/KzK5uxGxch?= =?us-ascii?Q?nxDafk7QdOKVa18dnvT5xjuw/lILAI9VjvPD7Uo+YQKMBm+yyle7Zy9K/Ry8?= =?us-ascii?Q?5oHkiGRJXPwXa9UCSmz8JyMJdM3UM6O0Ji93N1V+hZxP8t1U0yATE5y7Swi5?= =?us-ascii?Q?0UsKO88ACpvIYSWeR1sI9739vzssj9ckn3ElVXRcaA3iNORIqk8xals35l6j?= =?us-ascii?Q?sQWb/1WUpRRHcs9fcafW/oxcezoiZjkobpm/dtgrK0igu3onMqLn2rPSMve9?= =?us-ascii?Q?vOA/baKmiEryElyqvyDgm4rUlqj6wQe4dJP0vHDgkxHuOHGBvKDjfD6Hq7fJ?= =?us-ascii?Q?/ed3737dRi0/q9sJx/5gXsne+/dZPp/AxzMADVEkpDdYVvjVA8gzmqoRKHpA?= =?us-ascii?Q?/UC7+8D/ca6PY6KVoZ8CgLKHaYt1+kbY8puo47eYuAWy8579PRjO4/i1728v?= =?us-ascii?Q?Z0mT+9NwmadJ77QYclqseO9/JbFSbliLGhhMbNL1I63OtA1RDOU35V8JGkn8?= =?us-ascii?Q?QGSq6l9FyNWTzfx3cOjkJ7fndPo3GJxWnAKbo97gUOPJs8CFjZi1Rm6Q9fFQ?= =?us-ascii?Q?jA1C8uFABV1qtgQkWVPDb5BNvytLduijcSP4lKFGuO7Mij09hFhepkcARjei?= =?us-ascii?Q?2qhlf24GcAPTa05/w2EttUoL9WjwSAUK4hFx5RN60Zyvc6PzQ5J/+2R4iDeW?= =?us-ascii?Q?Iqb9rF1YYBVPv/bFfxAW9Ii+jmSMMXgDIZxDhyeMLMMG+hgzcC4F/zUvODPi?= =?us-ascii?Q?0rLAHTuMLNXIcx433SRrwGCtLN9FKD6kXa8j8NNJD8/8JcSPlBH4xox9tftG?= =?us-ascii?Q?6nQMuWjdJw=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: f0cab190-ecff-43f5-93ea-08defbbd2811 X-MS-Exchange-CrossTenant-AuthSource: DM6PR12MB4827.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 16 Aug 2026 17:38:17.5603 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: UrboQXHnroNPJY7r+DZJAs0InVFF1apfCZkNS/D1vu2gko0JCm1OHz3W5x0cobVtErUw5TwzbwJjkRvoI4gvuw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: LV0PR12MB999092 The reject DSQ drain will be generalized for placement failures outside sub-scheduler capability rejection. Move the drain into the core sched_ext implementation first so the subsequent behavioral changes can be reviewed separately. No functional change. Signed-off-by: Andrea Righi --- kernel/sched/ext/ext.c | 49 ++++++++++++++++++++++++++++++++++++++++++ kernel/sched/ext/sub.c | 45 -------------------------------------- kernel/sched/ext/sub.h | 2 -- 3 files changed, 49 insertions(+), 47 deletions(-) diff --git a/kernel/sched/ext/ext.c b/kernel/sched/ext/ext.c index 2739cd180bd74..0cb9ce0f8d4ed 100644 --- a/kernel/sched/ext/ext.c +++ b/kernel/sched/ext/ext.c @@ -4668,6 +4668,55 @@ static void process_deferred_reenq_users(struct rq *rq) } } +#ifdef CONFIG_EXT_SUB_SCHED +/* + * Drain @rq->scx.reject_dsq, reenqueueing each task so the BPF re-decides + * from p->scx.reenq_reason_*. + * + * A task can be re-rejected repeatedly. The reenqueue is bounded per task in + * scx_do_enqueue_task(), which ejects the owning sub past SCX_REENQ_MAX_REPEAT. + * Rejection can't happen for root. + */ +static void scx_reenq_reject(struct rq *rq) +{ + LIST_HEAD(tasks); + struct task_struct *p, *n; + + lockdep_assert_rq_held(rq); + + if (!scx_has_subs() || list_empty(&rq->scx.reject_dsq.list)) + return; + + /* + * Move to a private list so a task re-rejected by the + * scx_do_enqueue_task() below isn't revisited this round. + */ + list_for_each_entry_safe(p, n, &rq->scx.reject_dsq.list, scx.dsq_list.node) { + /* migration_pending tasks should have bypassed to local DSQ */ + if (WARN_ON_ONCE(p->migration_pending)) + continue; + + scx_dispatch_dequeue(rq, p); + + if (WARN_ON_ONCE(p->scx.flags & SCX_TASK_REENQ_REASON_MASK)) + p->scx.flags &= ~SCX_TASK_REENQ_REASON_MASK; + p->scx.flags |= SCX_TASK_REENQ_CAP; + + list_add_tail(&p->scx.dsq_list.node, &tasks); + } + + list_for_each_entry_safe(p, n, &tasks, scx.dsq_list.node) { + list_del_init(&p->scx.dsq_list.node); + + scx_do_enqueue_task(rq, p, SCX_ENQ_REENQ, -1); + + p->scx.flags &= ~SCX_TASK_REENQ_REASON_MASK; + } +} +#else +static void scx_reenq_reject(struct rq *rq) {} +#endif + static void run_deferred(struct rq *rq) { process_ddsp_deferred_locals(rq); diff --git a/kernel/sched/ext/sub.c b/kernel/sched/ext/sub.c index 2258cc94e6661..dcb3f8fd1951c 100644 --- a/kernel/sched/ext/sub.c +++ b/kernel/sched/ext/sub.c @@ -774,51 +774,6 @@ bool scx_task_reenq_on_cap_revoke(struct rq *rq, struct task_struct *p) return true; } -/* - * Drain @rq->scx.reject_dsq, reenqueueing each task so the BPF re-decides - * from p->scx.reenq_reason_*. - * - * A task can be re-rejected repeatedly. The reenqueue is bounded per task in - * scx_do_enqueue_task(), which ejects the owning sub past SCX_REENQ_MAX_REPEAT. - * Rejection can't happen for root. - */ -void scx_reenq_reject(struct rq *rq) -{ - LIST_HEAD(tasks); - struct task_struct *p, *n; - - lockdep_assert_rq_held(rq); - - if (!scx_has_subs() || list_empty(&rq->scx.reject_dsq.list)) - return; - - /* - * Move to a private list so a task re-rejected by the - * scx_do_enqueue_task() below isn't revisited this round. - */ - list_for_each_entry_safe(p, n, &rq->scx.reject_dsq.list, scx.dsq_list.node) { - /* migration_pending tasks should have bypassed to local DSQ */ - if (WARN_ON_ONCE(p->migration_pending)) - continue; - - scx_dispatch_dequeue(rq, p); - - if (WARN_ON_ONCE(p->scx.flags & SCX_TASK_REENQ_REASON_MASK)) - p->scx.flags &= ~SCX_TASK_REENQ_REASON_MASK; - p->scx.flags |= SCX_TASK_REENQ_CAP; - - list_add_tail(&p->scx.dsq_list.node, &tasks); - } - - list_for_each_entry_safe(p, n, &tasks, scx.dsq_list.node) { - list_del_init(&p->scx.dsq_list.node); - - scx_do_enqueue_task(rq, p, SCX_ENQ_REENQ, -1); - - p->scx.flags &= ~SCX_TASK_REENQ_REASON_MASK; - } -} - /* record a caps change, see struct scx_caps_updated */ static void caps_updated_record(struct scx_pshard *ps, const struct scx_cmask *cids, u64 caps, struct list_head *to_deliver) diff --git a/kernel/sched/ext/sub.h b/kernel/sched/ext/sub.h index f7bcdfda8dd85..8f2425bdb9530 100644 --- a/kernel/sched/ext/sub.h +++ b/kernel/sched/ext/sub.h @@ -37,7 +37,6 @@ void scx_discard_stale_ecaps_syncs(void); struct scx_dispatch_q *scx_resolve_local_dsq(struct scx_sched *sch, struct rq *rq, struct task_struct *p, u64 *enq_flags); bool scx_task_reenq_on_cap_revoke(struct rq *rq, struct task_struct *p); -void scx_reenq_reject(struct rq *rq); void scx_rescue_charge(struct rq *rq, s64 delta_exec); void scx_rescue_end(struct rq *rq); bool scx_rescue_keep(struct rq *rq, struct task_struct *p); @@ -93,7 +92,6 @@ static inline void scx_discard_ecaps_to_sync(s32 cpu, struct scx_sched_pcpu *pcp static inline void scx_discard_stale_ecaps_syncs(void) {} static inline struct scx_dispatch_q *scx_resolve_local_dsq(struct scx_sched *sch, struct rq *rq, struct task_struct *p, u64 *enq_flags) { return &rq->scx.local_dsq; } static inline bool scx_task_reenq_on_cap_revoke(struct rq *rq, struct task_struct *p) { return false; } -static inline void scx_reenq_reject(struct rq *rq) {} static inline void scx_rescue_charge(struct rq *rq, s64 delta_exec) {} static inline void scx_rescue_end(struct rq *rq) {} static inline bool scx_rescue_keep(struct rq *rq, struct task_struct *p) { return false; } -- 2.55.0