From nobody Fri Dec 19 17:01:31 2025 Received: from NAM12-BN8-obe.outbound.protection.outlook.com (mail-bn8nam12on2070.outbound.protection.outlook.com [40.107.237.70]) (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 807CA1D0496 for ; Wed, 4 Sep 2024 11:14:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=40.107.237.70 ARC-Seal: i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725448443; cv=fail; b=WrAzS3Vevkroonneo/fYzGE0DYUsBAuc/V8CtMp/dA+n3cKJTdJ9RodaX5956u6Xlm1Ia9ABLZqJruNR/at1BLMCvrf969tH+vONBHTnZeo3ZGpjxlp6LzxgH9hOnHnmmLNXe0hAjxHgcwWnao7RlJYdyQXuiP4SUsodPJ5AVyA= ARC-Message-Signature: i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725448443; c=relaxed/simple; bh=rW9oMdchcSXhTxjIhP42sq/2bvWvY5nOLqf4/4xokzc=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=e5jRHe10PjSkBdmTBLIRtEIG05ITEFfEMQ1Cg0IXZ/HsDGcKlJdwcE+V8A7G5S8GzRBHFaOVSNxaiRK8dtDIKEUBbjTGvNys3kUB2Rwjen5Obd6Y2JWwBlw+C6j2WVji8e+tVeMZpoyezqG64BqSj4tLoXg76HRqPjdycUy58/A= ARC-Authentication-Results: i=2; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amd.com; spf=fail smtp.mailfrom=amd.com; dkim=pass (1024-bit key) header.d=amd.com header.i=@amd.com header.b=Q9QnUCKl; arc=fail smtp.client-ip=40.107.237.70 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amd.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=amd.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amd.com header.i=@amd.com header.b="Q9QnUCKl" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=SuroHaK9Ev0LeFn92PSDbsvDKqp7moa8rcTfMJwG7P8WrGZIV2MNzXex10/6QaAjfIlZoH74cArVLkOlCUYzVKylblgjyGDDYgRfhAwc7zA7mCjeqhGDQ7bfXZDeU3aTdXrCJ8PrsvBtVpNy8CUwuroICd5gba5AQ4pGV4sAGhmaKAmM290ggETX8UZhBAq2g1Ckci64zBAOBjS4EpPKqaeeWrjj4KkuleFLZ3+Wn2tOx+55LDSzQll5cdURHOHscb24qvn52sqeIJyZMiIot3U2zcs7tS/6xs6G3f78muEWCWKTJNbFIivDBjDM7pGDMmjiktd0mkfHbMdPKKiqFA== 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=4J+HF716Z83F8jQvwpIqkoxs5ThrrkXqT7/zvYwyuL4=; b=dGsobRgl1MMQQtJyi7+dkllsVbz1NyXIjE26EzFCjBoDJSJgrGl7UtPfRVOMlfJaFhKXmlZkW3EQkz8VrUDNKaC2kqbZkb+Ce8cA5dYzNc8X9vOo/nnfJK8HKkg/+hQBW98T/jS90vOJpbCqFVyMre0cuXTSFpRkZhmaUv9oaeqMF/+xzsXlsKl++T6TaCDa5wB77F45ifIAdBpvzUKBji7alxHuq975yg+9T3UtXWjhfede/FAS7+h4Pkdoyu5emLn4pfRT0F22dEEg1JxWdpoRxjFM6D333DnPlXBGPsTZGLPBIrQe1Y2JiEBb6hlrMSzESIqoVt7jaAxp6BoJBw== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass (sender ip is 165.204.84.17) smtp.rcpttodomain=redhat.com smtp.mailfrom=amd.com; dmarc=pass (p=quarantine sp=quarantine pct=100) action=none header.from=amd.com; dkim=none (message not signed); arc=none (0) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amd.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=4J+HF716Z83F8jQvwpIqkoxs5ThrrkXqT7/zvYwyuL4=; b=Q9QnUCKlns2TImqUhqmIl0YjfgZagRrmjaV/+2L8Ez16tH/v+2Y7FXDEr9iwA503LnHTcNjhI0BQaaLs2FcGC/b/0mcIv/BI7Gru4EXZu0pMn3/muKjkvtB/IDAesdD09gH1SJIfWTaB2OLggO1Tk6SJtLAIjp2x3raV/eLllQg= Received: from MN0PR02CA0013.namprd02.prod.outlook.com (2603:10b6:208:530::27) by SA1PR12MB7442.namprd12.prod.outlook.com (2603:10b6:806:2b5::15) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.7918.27; Wed, 4 Sep 2024 11:13:56 +0000 Received: from BN3PEPF0000B070.namprd21.prod.outlook.com (2603:10b6:208:530:cafe::94) by MN0PR02CA0013.outlook.office365.com (2603:10b6:208:530::27) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.7918.27 via Frontend Transport; Wed, 4 Sep 2024 11:13:55 +0000 X-MS-Exchange-Authentication-Results: spf=pass (sender IP is 165.204.84.17) smtp.mailfrom=amd.com; dkim=none (message not signed) header.d=none;dmarc=pass action=none header.from=amd.com; Received-SPF: Pass (protection.outlook.com: domain of amd.com designates 165.204.84.17 as permitted sender) receiver=protection.outlook.com; client-ip=165.204.84.17; helo=SATLEXMB03.amd.com; pr=C Received: from SATLEXMB03.amd.com (165.204.84.17) by BN3PEPF0000B070.mail.protection.outlook.com (10.167.243.75) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.20.7962.2 via Frontend Transport; Wed, 4 Sep 2024 11:13:55 +0000 Received: from BLRKPRNAYAK.amd.com (10.180.168.240) by SATLEXMB03.amd.com (10.181.40.144) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.39; Wed, 4 Sep 2024 06:13:48 -0500 From: K Prateek Nayak To: Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , "Mel Gorman" , Valentin Schneider , "Thomas Gleixner" CC: Leonardo Bras , "Paul E. McKenney" , Rik van Riel , Thorsten Blum , Zqiang , Tejun Heo , Lai Jiangshan , Caleb Sander Mateos , , K Prateek Nayak , "Gautham R . Shenoy" , "Chen Yu" , Julia Lawall , "Sebastian Andrzej Siewior" Subject: [RFC PATCH v2 4/5] softirq: Unify should_wakeup_ksoftirqd() Date: Wed, 4 Sep 2024 11:12:22 +0000 Message-ID: <20240904111223.1035-5-kprateek.nayak@amd.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240904111223.1035-1-kprateek.nayak@amd.com> References: <20240904111223.1035-1-kprateek.nayak@amd.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: SATLEXMB04.amd.com (10.181.40.145) To SATLEXMB03.amd.com (10.181.40.144) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BN3PEPF0000B070:EE_|SA1PR12MB7442:EE_ X-MS-Office365-Filtering-Correlation-Id: af520b3b-d241-41a3-1925-08dcccd2aa93 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|7416014|376014|36860700013|82310400026|921020; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?DihNESGGPHwr1IcaO+OyYiWkjpUYnIXmtGAvJVIMQV+FWBvamx3NyePDxCNf?= =?us-ascii?Q?m538jvs11LyWZtSs33U6wqxyV1ISgfMkLjjQAcu6vxJU4fEhN2T+6BMi1+Gv?= =?us-ascii?Q?e5tT5pbU9VeJXoQhyuEw7iYndjaKKfva5yPrwaylyqg304pdWPXcEzjFIeQo?= =?us-ascii?Q?I9AzV6iUJlvGm6SMNuXMUGgAijveDNV0Nh+nJfsTRu/ltoDU8ykP1hxN8FP4?= =?us-ascii?Q?jlEUoANNdxG0DG/AAu1EoqpNAxkuLcjZpXObzAUlQWWjaT5ZvPwTh8MQu3Qp?= =?us-ascii?Q?wjjaNbMNWireGESL+F2f8SUTcOSct037XodsxdBe0z6lZOthlNvuFhepuRuc?= =?us-ascii?Q?Wu8DyRVgaXTVMh+RU3SqX7f6q71nOsiRk8eYxn/p/dgL0Dz9NXVk39aQOMlB?= =?us-ascii?Q?9ZY8TtINjyWWgkayGju3EgWFhRYH9OoZtPoj1+t+9LEa9vkePyjd4Q0ftJ+D?= =?us-ascii?Q?/Pi9CCklkp9nMESq+jfKb2ENs8Kdk44YLjxuP0cEHHvEfJpWw4qqVPotO6lz?= =?us-ascii?Q?VjZkWZh3222iH0NckveEmb6HdYpF00BXSCVdMeoKdCrigVNUh76o8AzO+K6R?= =?us-ascii?Q?jH5yiUoUmUYpUHP8f/lXCg3rc7WAadSYGjDkKFWYtQJ6/lWcVxAZGcPHTvBF?= =?us-ascii?Q?Klh5IHBx59F4Ulljh492PPJHYkN/y7P/7KqVG5524DTPnh0OCzkxcEIWYn60?= =?us-ascii?Q?C+C1Mms5c/Ge8jbdDlteBd34LBQfAWSVtl1pwyMMONiqWrEWtKozO4DpRdUz?= =?us-ascii?Q?sMOPrZpvfRcVwc/JYel3deLrp5Bf+aI1Noc3WlkeM1I+01u5Li+dLNQvBMHF?= =?us-ascii?Q?flBnhHn5DH2r1X5qbHYPL4cdg3rWeS7M4Hm7eLVofPry0M2RSvmo0oYW6hJm?= =?us-ascii?Q?x+eYdtUTvmlXtvO4V5UoJjXv/YBlIh1+sr9eus2TvfoHlYLT7v41+Wi4IIhB?= =?us-ascii?Q?iqsc2Jz3u6MhF9eZqLDDw2lJUZs9OGLhYAt2xox4MpSqvh/0JKlTV/G7j1kX?= =?us-ascii?Q?+06YqHgJaBuiqXiP4Ht1wVAAvcbAOS5WdRDZ9/w0hOmiRtqauJXb17YzKud1?= =?us-ascii?Q?ZHJRKzqE2gAI55JgNQ5xTfW2H3otXqlTcFIUVkGyQ3fqYupMDJ7oDmBIyCS1?= =?us-ascii?Q?sb5Tynu3DSyq7wgqohej4vgxbdCigI/eUF3ysMfn4Ym+ycJszKbiBDb7M5HL?= =?us-ascii?Q?1aIsRLQZ4eNndM//cTZrBvCdtnC5+yPSqqOL1Erc7O8fSwuXLv/v7QkW5vhB?= =?us-ascii?Q?gXw5gFGPZ+e3mCJhXtzaNPAFQ2I03khY/mkkhrp0Qt3CsvS+vJwxzb456c2Z?= =?us-ascii?Q?zkdlL27myrjFVeRIUlol3YcezFxrc4+uDPDiZ0tIRwwG17pnRackW1F2eSmC?= =?us-ascii?Q?w+iHMw9+yDM7hsx8jY2vmkEaccZCeDRYnjgAUGWxlEBYsAE60XGBr/+asprY?= =?us-ascii?Q?cXD+bTrGCFkvXd5bFSETAts9302B+9QtDp9xaXGBhu3NyznB9raqlg=3D=3D?= X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:SATLEXMB03.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(1800799024)(7416014)(376014)(36860700013)(82310400026)(921020);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 Sep 2024 11:13:55.5951 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: af520b3b-d241-41a3-1925-08dcccd2aa93 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=[SATLEXMB03.amd.com] X-MS-Exchange-CrossTenant-AuthSource: BN3PEPF0000B070.namprd21.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA1PR12MB7442 Content-Type: text/plain; charset="utf-8" Define softirq_ctrl::cnt for !PREEMPT_RT kernels too and unify should_wakeup_ksoftirqd() to return based on softirq_ctrl::cnt. Since these counts can change quite frequently when running interrupt heavy benchmark, declare per-cpu softirq_ctrl as cacheline aligned. No functional changes intended since !PREEMPT_RT kernels do not increment the softirq_ctrl::cnt (yet) and should always return true mimicking the current behavior. Signed-off-by: K Prateek Nayak --- v1..v2: - New patch. Broken off from approach discussed in https://lore.kernel.org/lkml/880f13fd-753d-2c5a-488a-d75c99e8dfa3@amd.com/ - Cacheline align softirq_ctrl since benchmark stressing the IPI path showed sensitivity to softirq_ctrl being aligned vs unaligned. This was also observed on v1 and has been elaborated in https://lore.kernel.org/lkml/20240710090210.41856-4-kprateek.nayak@amd.co= m/ --- kernel/softirq.c | 55 ++++++++++++++++++++++++------------------------ 1 file changed, 27 insertions(+), 28 deletions(-) diff --git a/kernel/softirq.c b/kernel/softirq.c index e70a51d737ee..d8902fbcdebf 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -88,23 +88,6 @@ EXPORT_PER_CPU_SYMBOL_GPL(hardirqs_enabled); EXPORT_PER_CPU_SYMBOL_GPL(hardirq_context); #endif =20 -/* - * SOFTIRQ_OFFSET usage: - * - * On !RT kernels 'count' is the preempt counter, on RT kernels this appli= es - * to a per CPU counter and to task::softirqs_disabled_cnt. - * - * - count is changed by SOFTIRQ_OFFSET on entering or leaving softirq - * processing. - * - * - count is changed by SOFTIRQ_DISABLE_OFFSET (=3D 2 * SOFTIRQ_OFFSET) - * on local_bh_disable or local_bh_enable. - * - * This lets us distinguish between whether we are currently processing - * softirq and whether we just have bh disabled. - */ -#ifdef CONFIG_PREEMPT_RT - /* * RT accounts for BH disabled sections in task::softirqs_disabled_cnt and * also in per CPU softirq_ctrl::cnt. This is necessary to allow tasks in a @@ -118,14 +101,40 @@ EXPORT_PER_CPU_SYMBOL_GPL(hardirq_context); * the task which is in a softirq disabled section is preempted or blocks. */ struct softirq_ctrl { +#ifdef CONFIG_PREEMPT_RT local_lock_t lock; +#endif int cnt; }; =20 -static DEFINE_PER_CPU(struct softirq_ctrl, softirq_ctrl) =3D { +static DEFINE_PER_CPU_ALIGNED(struct softirq_ctrl, softirq_ctrl) =3D { +#ifdef CONFIG_PREEMPT_RT .lock =3D INIT_LOCAL_LOCK(softirq_ctrl.lock), +#endif }; =20 +static inline bool should_wake_ksoftirqd(void) +{ + return !this_cpu_read(softirq_ctrl.cnt); +} + +/* + * SOFTIRQ_OFFSET usage: + * + * On !RT kernels 'count' is the preempt counter, on RT kernels this appli= es + * to a per CPU counter and to task::softirqs_disabled_cnt. + * + * - count is changed by SOFTIRQ_OFFSET on entering or leaving softirq + * processing. + * + * - count is changed by SOFTIRQ_DISABLE_OFFSET (=3D 2 * SOFTIRQ_OFFSET) + * on local_bh_disable or local_bh_enable. + * + * This lets us distinguish between whether we are currently processing + * softirq and whether we just have bh disabled. + */ +#ifdef CONFIG_PREEMPT_RT + /** * local_bh_blocked() - Check for idle whether BH processing is blocked * @@ -270,11 +279,6 @@ static inline void ksoftirqd_run_end(void) static inline void softirq_handle_begin(void) { } static inline void softirq_handle_end(void) { } =20 -static inline bool should_wake_ksoftirqd(void) -{ - return !this_cpu_read(softirq_ctrl.cnt); -} - static inline void invoke_softirq(void) { if (should_wake_ksoftirqd()) @@ -419,11 +423,6 @@ static inline void ksoftirqd_run_end(void) local_irq_enable(); } =20 -static inline bool should_wake_ksoftirqd(void) -{ - return true; -} - static inline void invoke_softirq(void) { if (!force_irqthreads() || !__this_cpu_read(ksoftirqd)) { --=20 2.34.1