From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from BN8PR05CU002.outbound.protection.outlook.com (mail-eastus2azon11011063.outbound.protection.outlook.com [52.101.57.63]) (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 7FCBA3C3F54 for ; Tue, 15 Sep 2026 13:35:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=52.101.57.63 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789479344; cv=fail; b=VpozRXz4Q7BdOMD3ZEb3s3sNTlGwDgmKxmv1FF5T9iHQSZTV0hmkFYA/fXOf0C1H9P81acGUmCqiqUxBDI4yNJcshP/5rXGz0dC5O0UNDvuNxdtuWLrX9TAY/2Lh7FSuMWNN357X1RIyFOjk/scS3qjyRCoXcb2GHOOYBv3CKk8= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789479344; c=relaxed/simple; bh=aqQgcaPUUk0teXvv4hHNJ5tBdh2jRTFXSYvKs6dvmDs=; h=Date:From:To:Cc:Subject:Message-ID:References:Content-Type: Content-Disposition:In-Reply-To:MIME-Version; b=O1henrwLyAeZdajtBdMF1U4W/8OW3VXy2821uU9HHP8bo10HUIOmDUV3HbussR3JS0r0RMfS5hJiNlm7j5U9TuxhAwYMSigjiQXouBt0Cr1vAHWetuz2kNV81KNynfQMRhiB95GHf9nIZeCqxgn0SXBAW3rGImkjlzoCdxwo+7Q= 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=N2bUJ84p; arc=fail smtp.client-ip=52.101.57.63 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="N2bUJ84p" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=VIgdBz2GzgvUkcPandvxG/HK8Xbzx2J1Xvom8dNKc0ajTBUbjWv0waL8OlcHQKIejt9SdKirR/QwunZimt4b9t/IBPbPxRU8XqI4NIINutwlmCZNbvPJ1R0ldIxOp6XH17dDAnOuZXT8dUOZ09f94JKUqqEDo3fjInR/hMo9hJtVK6e9JqWCs0K5TMjcsB7/C6BI3romZ1PRKf9qeJ8+liQAmxGJSnr8dulopyoBfa6/VewySf1RH3J74LvEhQiiHlL7k5EyZK9IY5lvmQL6mz3+MrbqVOVwZqqEUNYSpwQV7+rvfEedbISQvLvOeEhJrTq6d/KAdVYGnMLrLMtB1g== 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=20Gys+Luuwi0Gy6eHj+vOBys+GAMZ/wYvFbxaaBgm1Y=; b=vFtQ7MEJGQaQ2KLcvWE6qjR6+SYQWX0tjAlIJTnm73JqTdfNligzlR2tjInwvYcF07tTGjmFnHbc3PnmFnJcjMw8axHEYRXmlJkAXAwWy9fY7J+M9zTecqFb3QIFkt8Ebq7WQLfpDZv2xfXlRkrF1wrQkGUbl1+rCM7YpPEtfLdNO/JDiBi8/quCFvUSZZnOhIZP+gEBLTVIbgwOJDZi/6Z+FKqZ3AY72Hrw1ZWH1dZC+7B9EtjwGqL4nE1KMtigT+WZiOVkKNoxFeiojvUiHg1OKIpN17mUanKAyHx+16FX/p7QwepyGHj3tzbe88nhgkBCGC6rr3QUXD1gyFmlEw== 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=20Gys+Luuwi0Gy6eHj+vOBys+GAMZ/wYvFbxaaBgm1Y=; b=N2bUJ84pPr7So0xBrXe/ZTza1mPmGKvqwgN8rn2YxyTNIh8pTHqamyW0vuwilTxLks6oLhLL4Xuerl7mPwgWbF12DJIhVvBlbbK0Bbw1AeiR372VtXdOcGeh8oX/bVgYjcv6osGaEA8bV1VlKDftXqIPwTH2sl3qVIFPnWf6sISWu/Rvh4CIOu+6vwmG3+RIc9/UgMXBSzLGeeHQjujOzEhqXp0d91iSHGhzIeDLMi1nFyYT3WA3l7VpfxEtpSxt0hIBeuShuiKNvImgaCXmh4o+YBanxafneRrQEyCN+HjZB+dzjdIVjyEeAPQ5O+fgBVutsPy30ZXqwPecRsvYmQ== 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 IA0PR12MB8279.namprd12.prod.outlook.com (2603:10b6:208:40c::16) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.406.12; Tue, 15 Sep 2026 13:35:35 +0000 Received: from DM6PR12MB4827.namprd12.prod.outlook.com ([fe80::6261:3040:864b:159c]) by DM6PR12MB4827.namprd12.prod.outlook.com ([fe80::6261:3040:864b:159c%7]) with mapi id 15.21.0406.007; Tue, 15 Sep 2026 13:35:35 +0000 Date: Tue, 15 Sep 2026 15:35:25 +0200 From: Andrea Righi To: Cheng-Yang Chou Cc: Tejun Heo , David Vernet , Changwoo Min , Emil Tsalapatis , sched-ext@lists.linux.dev, linux-kernel@vger.kernel.org, Ching-Chun Huang , Chia-Ping Tsai , chengyang.chou@mediatek.com Subject: Re: [PATCH 2/2] selftests/sched_ext: Add lazy preemption tests Message-ID: References: <20260914084955.1798562-1-arighi@nvidia.com> <20260914084955.1798562-3-arighi@nvidia.com> <20260914225115.Gb03c@cchengyang.duckdns.org> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260914225115.Gb03c@cchengyang.duckdns.org> X-ClientProxiedBy: MI1PEPF000008CF.ITAP293.PROD.OUTLOOK.COM (2603:10a6:298:1::42c) 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_|IA0PR12MB8279:EE_ X-MS-Office365-Filtering-Correlation-Id: 899d71bb-f7d9-4f87-88b8-08df132e3807 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|366016|7416014|23010399003|1800799024|56012099006|11063799006|4143699003|10067099003|18002099003|22082099003|6133799003; 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)(23010399003)(1800799024)(56012099006)(11063799006)(4143699003)(10067099003)(18002099003)(22082099003)(6133799003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?7QHbPGLqK7qHJhwdv/6xOIbcX7msCnMH4z++nAgbCzDooK2IA5c4G8zM4UH8?= =?us-ascii?Q?FYAy8FxmgBxGCRURWR2A9fUGo3Dpvz2Uraa4+du015iTOgZiEu3xvl5wJJ7N?= =?us-ascii?Q?F7A4YtrRsJC0bD1V2s2HGTPoptn2VOBX21Jam9iYOY28aZfR5jRatO72a2Pm?= =?us-ascii?Q?0MzlPzxXafItN9+LanAeqGgI5VqTu24LGbs4Vz5TAfD2mCawdMXKKAZ5Kpc+?= =?us-ascii?Q?QyNaetkFMGHQxSsI9Y39qqua4yBsauYCGQpAqomV+a0J6dJqALAT68yognZQ?= =?us-ascii?Q?3jnIeIgZq3rIbL+Xz+z3OBPwgJyc6x4W/OpbB8W1SDTkcgE0BoMT02t5rkzT?= =?us-ascii?Q?aWUTkQATjvW4JfVgYmmSbv0IW6H+qcg5LCBk89iipV7qjVBM6mGcAX8u53TU?= =?us-ascii?Q?4llThBuSWx9Ue0u5UJx1ugZZ6QpWEwFTshfQHc+48oqAvxoMYiwuAcZyIvn4?= =?us-ascii?Q?SQEi67UgTP40/HaHsz+lbyFXDnYslZMnZ3NcVtEmvIJ1M4U/ETnB3uf1gVzs?= =?us-ascii?Q?hLM7xPIU8eyzaAnek9tLgbVbE4BeLqlF+qPoMTdAZFlooy+piNVHXZf3ufQC?= =?us-ascii?Q?/eSByAnLp6MamFGJ5SOKS9TatmjEVwnj8L8PUDKn2HktDYumEysOf0PSTDtL?= =?us-ascii?Q?bL7kLT/zURtzbXEX17AMiI6zMKtNS9CLGfhE+FDxuRI3WuDmX0WI7NgwQKXx?= =?us-ascii?Q?haZ5QYpZWlvluu+5ts8V2D4F0E/EF0mIZTujx5JSQYfjNA4SJnKqTx6bl6dN?= =?us-ascii?Q?kvLxGU0EuOFP4ceSOw4dg8cfVRYQVx8D4EYjtlF1/cFmJWiSyJKb6kwiIUCs?= =?us-ascii?Q?XPXHO1eoIvgfg+4nHcxwTjV2kG6DThGxotzh1GpPLd04eotDmXwSrvw9cffk?= =?us-ascii?Q?fsmT6fviQc3ktYL/kXm5oD3kKpyZdRIyfE4aduskc+BrUmrjcE9I/3mHED0b?= =?us-ascii?Q?dXCMEIVUEyb8/49G+ZADqv2nqZGjWM0uG31nGNhY8PpBxpHrlZafphtTu8ym?= =?us-ascii?Q?BCpbpEGhs4O4x+7ncAJ8QT57wEAF73p6H/up1stvUncj3dUGq1tMvt561Q0+?= =?us-ascii?Q?VVpkSTZNBkIwgcu8b6Us1nVIlItvWmY8C5mYbn2C80wnJzGt8dBTD1ZihLyU?= =?us-ascii?Q?Ci4sBz/xC3p+EHbD7YDuEQid8IeeL1Vy/rcVRp+fAPc66rZhYAnA03vomTGX?= =?us-ascii?Q?fBAo/sFLOx5ooLpDFU4BL1ze6DOeR2VVSw1S8+Xe8ceekaFuvDvRZ9tmm7QS?= =?us-ascii?Q?ufwcjQ4hUsPPEi3vYfDgOoJg5NfiGYAGk/ZdHTrjGjFV6CHgVgO/W1A9rbRH?= =?us-ascii?Q?xpH46N+7jTt638upCzYJ3vTRuZA0mWA1ID7ZOBiXyeUWJ1lziYeBI2Pvk88C?= =?us-ascii?Q?4qEVY0u1AKWAL9XNAgpnvEu4gWD6kwHxQB/z6NhWhHirTCoupyUsaZR78nvn?= =?us-ascii?Q?xLMoSkykdOakZn4n8aOMM451cVNxLu73m7CdrXxXUS6EJhQjDCmDz1V7psvr?= =?us-ascii?Q?6+KCKiCqRXTSDB3YtTDbxbAfI2b24+vFRFqsc4JSQg8MB3k/u1BCv8YvD7Tn?= =?us-ascii?Q?mbDCrcyWqeOQfBnkOlikT0avMKKCIxkiGsqo49xNJJYPJmEUH/Y/rEBLL8At?= =?us-ascii?Q?2adFzouC93B4DTU5ta8vCLtTrXK/OcSmrY3dvpLOlJPMA5JFXeW8JhpSO+Oa?= =?us-ascii?Q?3BvuP3oXF9cTv4xXfFDSU/Lu2Fjwmt0awMFe47/zxDTCe8fC11vPEIyEWiE5?= =?us-ascii?Q?kdTx/Edm2A=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 899d71bb-f7d9-4f87-88b8-08df132e3807 X-MS-Exchange-CrossTenant-AuthSource: DM6PR12MB4827.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 Sep 2026 13:35:35.4652 (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: h24+BK/2WRfYhZgGzlV3+rq1euFG/M90flig4ap8jTjLztQx3RY2e5pHGYbRRhj4+4C0YdRhguFifESTusvgwQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA0PR12MB8279 On Mon, Sep 14, 2026 at 10:55:56PM +0800, Cheng-Yang Chou wrote: > Hi Andrea, > > On Mon, Sep 14, 2026 at 10:47:46AM +0200, Andrea Righi wrote: > > Add trace-based coverage for immediate and lazy preemption. An fexit > > probe on __resched_curr() records the requested TIF and the current task > > slice, while the stopping callback verifies that the task reaches a > > scheduling boundary. > > > > Exercise kick requests individually, in both orders and combined in one > > call. Verify that immediate preemption and WAIT take precedence over > > lazy preemption, and that combining immediate and lazy enqueue > > preemption follows the same rule. Also test overriding the expiry > > default in both directions through scx_bpf_task_set_slice_expiry(). > > > > Extend the NO_HZ_FULL test with infinite-slice victims. Verify that lazy > > enqueue and kick requests restart a stopped tick and make forward > > progress. Keep invalid kick flag coverage and skip modes not exposed by > > the running kernel. > > > > Signed-off-by: Andrea Righi > > [...] > > Didn't have time to go through the whole series, but I applied it on > for-next and built with PREEMPT_LAZY=y and PREEMPT_DYNAMIC=n: > > INFO: preemption mode unavailable; lazy TIF was 5, immediate TIF was 4 > ok 2 kick_lazy # > INFO: preemption mode unavailable; lazy TIF was 5, immediate TIF was 4 > ok 4 kick_tick # > PASSED: 6 > > > +static int active_lazy_mode(void) > > +{ > > + char buf[128]; > > + FILE *file; > > + > > + file = fopen("/sys/kernel/debug/sched/preempt", "r"); > > + if (!file) > > + return -1; > > sched_init_debug() only creates that file under CONFIG_PREEMPT_DYNAMIC, > and PREEMPT_LAZY can be built without it ("select PREEMPT_BUILD if > !PREEMPT_DYNAMIC"), so the two tests pass without comparing the TIFs. > > Would something like this work? > > if (!file) { > #if defined(CONFIG_PREEMPT_LAZY) && !defined(CONFIG_PREEMPT_DYNAMIC) > return 1; > #else > return -1; > #endif Ah yes, makes sense, we can include autoconf.h and check that. I'll include this fix in the next version. Thanks, -Andrea > } > > Thanks. > > > + if (!fgets(buf, sizeof(buf), file)) { > > + fclose(file); > > + return -1; > > + } > > + fclose(file); > > + > > + if (strstr(buf, "(lazy)")) > > + return 1; > > + if (strstr(buf, "(full)")) > > + return 0; > > + return -1; > > +} > > + > > -- > Cheers, > Cheng-Yang