From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from BYAPR05CU005.outbound.protection.outlook.com (mail-westusazon11010003.outbound.protection.outlook.com [52.101.85.3]) (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 52664423EB2 for ; Mon, 10 Aug 2026 15:16:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=52.101.85.3 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786375006; cv=fail; b=rsgXSyt2CU1qfe7qVUCrNxFmhZ3YKGpF6rg6Dc/qfQYK7O9wsjqL+cEgHr0FeOrWvo6igk2p/gmy14S6+FVzrjdiksDo6q2oOKpucesON/Yp1seJn5A4BIJNgCTRHFGINZxFT/2qqvyhT6MuqkrkNzMji+dwxcGeMGt/VVvLvZU= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786375006; c=relaxed/simple; bh=sC1vVW/wA9VS+F3pDXmAstmo4hC/EheKqMQsqw07jF0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: Content-Type:MIME-Version; b=gAr9yHo1sL19tGzjB1jwPsIBx3ad18VO+R7HtSsMepVx1+mhCexCYMLfxML/HvcOw1CsEUo60pQo5yhTe/xwuXq1SwvQTT65/biS3VEAK3zSgpKLjTJ8fQdIYxzzuTkskFqSJxmS2Q3dhFqbtvUMbSStTjWNhfBUAJLNN77EBso= 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=iORXAEek; arc=fail smtp.client-ip=52.101.85.3 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="iORXAEek" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=nF/Dx3oGZoBIW2x7kQq47wi7nxkF12QSX5SH5criHpkvJZqDv43RspJNlJWrrSpr9Ji+OE94HqN6J81OQ8cTie0SnrEez7aUd6Q4szYvtbrAAdss1IqU8TbjdsFm/I2xcVk1M7iDyHpRWDij9mXuTGJGwlkbF0DOeWdInh8sbgOzwvEenNW8+G9TQE3h3SDggRUbXQvECmqcPFYFtUWP5cMAuIo/AmPlLzlcAup66CjDdffhnFOcAzdll2GnYMpHRWu9KamPWjs59EyVXNnlwsX08yiji/YiiQ51X+D8SxnCztgrDl7rrBQ5yJvLhpBpbC5tLZOVQPrMvytpK86GQQ== 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=ZPOKVMC0q//4KZRVnVqQREQuG4QWn6kWSR9+P7IN1UI=; b=ZuimYc7HrkoNEmeN5SUHPq/6In+Ym80/PL8dVBq7uG9JJ0vR6k0us+IswVS8U2KlbhUgEMspsdxMa8R5iYMSROgknZpNuY15wpC5zmcQV/JB7/yCly9OIOtG73tPtEAD+m8UXvn9ro9/Z8Sg2WjPHGh4Ioj76d34KgOhZQuDyJpbA7T9SDxrrfBtyarP3BHWgAb8RBu710ILiscUv2Gptgxw+74J9ZMebttvaosxxIyM9VvrLqR7qZ5GEMeGQAFgGzkksv/q6oFscZtFhbrbRTzZ8U2gmPptiGh3sImtaPYxF3OLBcFWum0HbfJGTioWYvqVO4DAzGDd1EnlUOTvEQ== 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=ZPOKVMC0q//4KZRVnVqQREQuG4QWn6kWSR9+P7IN1UI=; b=iORXAEekKQmPWcSN0lFTCOeoN5iQ1sZeFy9YEbBUUtG0rbguKN+O0u7T/rNKE6xp22QiwhHcRfIQ0gQZkZqhc1mL+HZyjGphvlPQW0v6BEexxRjB2ohBB3okOZX9wIsSynFQzT3mQiXfPPrf35GyYvldBLKIwmIyebEjjYu5BwrGgjTa216V6lDdywOtl8siNkTUNRxB/ew0IVk8jyUKjENgKScnBk6ppDKCdJIZO6TF7GkmGvN+sOtZkTRKeNFdOBQoLOqtJvAcBR6LD+ehU/YySvzLOHLbrGu9pcUZ4vrYN0SssxN8nFxULAs0mX+9mfG4c9EsiZ5VL4YngIokBg== 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 IA0PR12MB8327.namprd12.prod.outlook.com (2603:10b6:208:40e::11) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.292.25; Mon, 10 Aug 2026 15:16:39 +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 15.21.0292.024; Mon, 10 Aug 2026 15:16:39 +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 08/15] sched_ext: Move reject DSQ draining into core Date: Mon, 10 Aug 2026 17:13:54 +0200 Message-ID: <20260810151523.86994-9-arighi@nvidia.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260810151523.86994-1-arighi@nvidia.com> References: <20260810151523.86994-1-arighi@nvidia.com> Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: MI3PEPF00007544.ITAP293.PROD.OUTLOOK.COM (2603:10a6:298:1::4cf) 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_|IA0PR12MB8327:EE_ X-MS-Office365-Filtering-Correlation-Id: 16f45f15-db2d-488e-9046-08def6f26064 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|366016|7416014|1800799024|23010399003|11063799006|56012099006|10067099003|18002099003|22082099003; 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)(376014)(366016)(7416014)(1800799024)(23010399003)(11063799006)(56012099006)(10067099003)(18002099003)(22082099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?thIJAmXC/x3E5nSLslTtAGoTXqRZ5tgjSJ66cPfruuEEK6boV7xp90Ci+ZQu?= =?us-ascii?Q?fyyK0ehfm0XI0F4MHkLhTuuj1lqQKTAS2TV4poY0f547Sz5gqwJn4i2fMpcJ?= =?us-ascii?Q?if52x9LTdPQR+/hPp3sl78wBQXhlpwQTIgsk/2nqWHlSfPvvri0BxSl9u3zR?= =?us-ascii?Q?UmaGIdfocu7vi9ZrR3/+Fer+DeruSJcoKohzqO3aC3cV0XN5Ss+WieO2n/21?= =?us-ascii?Q?ZIAdJMx9ouRcPu0f4ph7Qxy8fwT0so7bmooqoSDitUmKAAjcISmjZ6SFxOku?= =?us-ascii?Q?zQ983nE1z/M7p+nVXHhdWQVCYVK/+eCgMHHbVjIQGP7rCa+2nFfWQ3zhyp4d?= =?us-ascii?Q?r0kVnbRGFJFsx1t2V6w57aRd6uRhX17ot3TOjGERaJ0MvRDy7+RnGYsquLcT?= =?us-ascii?Q?tdIPKK6oLfVB96HrS9kCMBzllmDb0hMgAmDzel9oTpYnAB7XVbYVaHpbiZ8H?= =?us-ascii?Q?CB9Wi6HKshaVPY+T6My0aW0UXf4eJYD1DWoy+s+xODOnE3Uc9lLjerWqk0rv?= =?us-ascii?Q?boL4uzpuCTfcDN0joD0cDlXeVl2deN6v/IN+BK3J6fjuCTY/LzmsB8AgDiRk?= =?us-ascii?Q?dNclirac/3xsTHmXaNWyU/KFpEr9QY5QKV8KvwhFbgf/lhZPKNhl3LTpwbk6?= =?us-ascii?Q?hhIj/O6WGbcU0oQXX9fRrk3fEpYNEc1ZXAcP0rZr7yDbYdwtX7sbE40/7e97?= =?us-ascii?Q?uMkBbTqQTTQCqlnth8+UMrI9K18STj0TMX5SondhzbsrAmlNXAuBO3Kzkq8+?= =?us-ascii?Q?ivJR10c+k99BFzHSFLwRfd6J5R/iH7ouH2Ef7rHEeDAe0LH5YS1rzGyTmSYf?= =?us-ascii?Q?3XZUJyTIllbK3KB4OxKYc/a205OQO/MlU3MMZquAoCCCXUsuzy3ZLXOUq7VK?= =?us-ascii?Q?Z1+p8fIwwMQuSrhfuIbZokWCXaKf19whKDZzsYeUcDQjHdijm5PsroYxe0It?= =?us-ascii?Q?B5Hc0MTdkZrPfyn8CyaKkvqdotm87GBik8j39HtCmA6KQxnsSCkyUSZPhmEz?= =?us-ascii?Q?tnwtKJW5zp1bjiTX4LZeKDrDsyRLG2bKNlyTJySO4nGG5MEaF8q3I+7YHRlJ?= =?us-ascii?Q?hsJFhKbvDRZHdRt6GcfioSH40E/8XtJYsR7nCLDZ9tuG7+qTuefkfQwpAeoL?= =?us-ascii?Q?ASuFTTIBocvrbR92tY/WZP9WLA6+PAeOHJu1cM1Tq9c/Xq86zijmvcCvAcD0?= =?us-ascii?Q?M/U/EqFci0HN7+/TpZIEaieSsrHvFTA4N15uR2JgAoP410jLS0nqvQlJkXC3?= =?us-ascii?Q?MQenN4O+l6zBHyMt+8iMqC1SHiYoHJOzPhsMy//IPOsODf/xXX0WVCfZUOXP?= =?us-ascii?Q?7+i5uRcq6tE6sRAZdtroFC1fhNva6oxogYhcjsv3JamAoZe/Laql3vrmqhrx?= =?us-ascii?Q?YYedor88HlHScXZKRbIEtuaavdwsKGUe41zSQJbg7JQA88MCP7pY3SlJK1uY?= =?us-ascii?Q?yQFdhMC9zHoDDXdJWiGSXrWObohOONR8KpRlg/Nnv8rPwMgLsrHdewQvu7kF?= =?us-ascii?Q?+3CMnisL7O0Y2L1NmWGGH3shOQIp/Xtxvu+iGZUNSdlVSkbsU26gVXbF/BQY?= =?us-ascii?Q?tlDny5i9P6k6QZAx4VRTNuUIzPocCexvhSgTjEvzjYr06799eWXeS71aTHix?= =?us-ascii?Q?AEc5V5kzJFR2jkIqT1sydwZTX2VMC9ZHlHxGCoDaZAnHWcNOZtsK6i16LnoS?= =?us-ascii?Q?Cd2TOcHQFfhLd1NhIVMXmtVxhxGjCmLxWIhjHc/utAaeITVtMghlYPDF3eEN?= =?us-ascii?Q?e8cKXmyvHA=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 16f45f15-db2d-488e-9046-08def6f26064 X-MS-Exchange-CrossTenant-AuthSource: DM6PR12MB4827.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 10 Aug 2026 15:16:39.4065 (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: uMT2Ja9gHdpt8czaK5XNR7xo9nT9NmI3TNoO9SksLpkMdM4FFQNTFmPV54XAXlwbg8q8jQWO7HccSJYQ/CIjVA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA0PR12MB8327 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. 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 0958622d4382d..1ad65b8051008 100644 --- a/kernel/sched/ext/ext.c +++ b/kernel/sched/ext/ext.c @@ -4582,6 +4582,55 @@ 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 9e1f1afd389f1..2391bb0c0ecb0 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