From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=pass header.oldest-pass=0 smtp.remote-ip=52.101.57.69 ARC-Seal: i=2; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=pass; t=1793628047; b=wV4gqVsI2Ab6kHHu25bWJ1YK0UK+aMlHYwMssGp+BPI6whkSgh3pXCferzdECmTw3FKQ X0/IDONZRcpoxWq1FIWzgxONjdFTg8wAPKoar+iwYIK8TgbHElyv6K02nGY9ktVVDUIqe +EjvUkSrRcd/ZyNcIVUYfjlSNLidSdZj/h/+uUzKqMYuZD10Y8v+Q/VrSq82OWwvk32dt wc815nbD1+EYRpbh6Ol0DFeF25NxwKSQhTTJsN/n5yCg1kPW4m5rSqTbjo3tb2icrPiPP SqqoNFVeVTibvLoXksGRgQ2rjBa7qU7gq9Vgr/o2xHSe7hQ9dTJEc7O96Jmr9rCLAMg== ARC-Message-Signature: i=2; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793628047; h=DMARC-Filter:DKIM-Signature:Received:Received:Content-Type:Date: Message-Id:Cc:Subject:From:To:Content-Transfer-Encoding:References: In-Reply-To:X-ClientProxiedBy:MIME-Version:X-MS-PublicTrafficType: X-MS-TrafficTypeDiagnostic:X-MS-Office365-Filtering-Correlation-Id: X-MS-Exchange-SenderADCheck:X-MS-Exchange-AntiSpam-Relay: X-Microsoft-Antispam:X-Microsoft-Antispam-Message-Info: X-Forefront-Antispam-Report: X-MS-Exchange-AntiSpam-MessageData-ChunkCount: X-MS-Exchange-AntiSpam-MessageData-0: X-MS-Exchange-AntiSpam-MessageData-1:X-OriginatorOrg: X-MS-Exchange-CrossTenant-Network-Message-Id: X-MS-Exchange-CrossTenant-AuthSource:X-MS-Exchange-CrossTenant-AuthAs: X-MS-Exchange-CrossTenant-OriginalArrivalTime: X-MS-Exchange-CrossTenant-FromEntityHeader: X-MS-Exchange-CrossTenant-Id:X-MS-Exchange-CrossTenant-MailboxType: X-MS-Exchange-CrossTenant-UserPrincipalName: X-MS-Exchange-Transport-CrossTenantHeadersStamped; bh=mRDn1cL/1SYCyQ55RQwTiHSmxsf05P1xQ/wT4Pde5p8=; b=CWVo8dVxSz9WddTG70qtMzgOOIQ4vL6i3eVQWz7RBBanwPlT8x6vq5t7319uygQLb52h IP/v8GdRxdW19XiO0tWzJ2D23BJCdD3Yf0SrznVLBsjuhu8Cy2Xeac6/bHDfBUbbYlgiE rAFlrSqPyLWdtDV4uEO/CKC3+TEI4lLADWVc1SaBxLrhnmVNDjs12CKlokBsA0/hYZQ1/ h8uE+H7pPapSdCEYPAmvUvKeQlD5sV055W6C0iIVS8FAnTaTNzgYg4TgElpZxTDTsNYG0 JNu25jZ4NxlzbsLLJdy3M82Lb/uA5ZotsomsRObi+u1981GxWYIg01rSdXLVIW84KWA== ARC-Authentication-Results: i=2; smtp.subspace.kernel.org; dmarc=pass header.from=nvidia.com; spf=fail smtp.mailfrom=nvidia.com; dkim=pass header.d=Nvidia.com header.i=@Nvidia.com header.a=rsa-sha256 header.s=selector2 header.b=sLPHcjvt; arc=pass header.oldest-pass=0 smtp.remote-ip=52.101.57.69 Received: from BN8PR05CU002.outbound.protection.outlook.com (mail-eastus2azon11011069.outbound.protection.outlook.com [52.101.57.69]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (secp384r1) server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A0F4460A5BE9; Mon, 2 Nov 2026 14:00:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org A0F4460A5BE9 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, unprotected) header.d=Nvidia.com header.i=@Nvidia.com header.a=rsa-sha256 header.s=selector2 header.b=sLPHcjvt ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=gasIeBKt98JsJpW9XagGGA7ViVgUXOQiWCZzhCMvfIFc6UsU/e/NEWSIQyrqQ/y5Gcx8mbDZeIhpRFfIEsbezWDuFRfBJlUgzPH2wcI7iVrpinQgEZ26O7IK3zp3Ln0VMcrHkYPJOQiQCPEZYuLi+ENtayDLhqKQFS0vTwjb6C9tqQTt9ZugfeXODUYHeZhkwTre+GleDjP597Tg7yXTkvKy2BjJqd12hRIN0FQhrMzNm/DFW5h5LvAZDvx+6bTWnspYUWbLg5pYtGCkdTt1XhSr94yVQKgC0m0OmJ4dVe5itIw2Zwbk19B7uUDNW6oKS9/f8bDMihQ4Q3Zd/DSFxw== 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=mRDn1cL/1SYCyQ55RQwTiHSmxsf05P1xQ/wT4Pde5p8=; b=zFKVMU8rUB6RCG/KIr2bz79afd5Ck99q9ecRPu536qTlZIpdSOOSfs9pjHrtIja3J9XRxsu1QVNHrj+cO5zl7fnhR/VKKeyYGLHeOPab2jGPswJYuckMXQqZzVp2XTjFdFmliHMp8QaHHvbmohI8BAf6Do+5ONzJYm0db7BfLWps7mCKbIy77Kr0Q6ICdh5FhCBsFdl73IZvdieY8zpiCMo1cQi/QP2kWK3oKr0setd5J+GXdT7KLlcM7q0/mkS0T7Sb0exWpugonDs8/pEuA//mJXZbKUydV2nT5/oSFRVEUPzuVoy2M0sI0JEpYZfMWosKFlNQMSm7vSn/aldyPw== 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=mRDn1cL/1SYCyQ55RQwTiHSmxsf05P1xQ/wT4Pde5p8=; b=sLPHcjvtijrqMxdXsOdN4UKGH2TU/fRvgDAD8z5ql8jz7Sou++UgyiUGWMeLulbzykMGJsjtXFc6sAtXz92hkcwn/Gw5hsvfLJnGgzDpkcYiY/37GLVA9OfYs0aG7joFgdyEttTkcEMWVI9i33+mdBaXBaZrllK3IQ9MWT1t7Mh+rijnFWnZaC5HQhO2RuXC36KILhbUiQkXHPVQ3um7YUK/1Atdi8Id6XDgyJAMUNhendtLOlP18S5TJ/yV4XhrSRwOwd20IkZAprNA1auDvxZeMLLzOGYn01eKdw+CBmuZ0F+DDgcA+TJI07ZTOWLrzgT8lP8IzjsGcCZohgpYfQ== Authentication-Results: mx.microsoft.com 1; dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from MW4PR12MB6873.namprd12.prod.outlook.com (2603:10b6:303:20c::17) by CY8PR12MB8195.namprd12.prod.outlook.com (2603:10b6:930:77::17) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.569.12; Mon, 2 Nov 2026 14:00:40 +0000 Received: from MW4PR12MB6873.namprd12.prod.outlook.com ([fe80::a338:bd2c:3a38:ece1]) by MW4PR12MB6873.namprd12.prod.outlook.com ([fe80::a338:bd2c:3a38:ece1%5]) with mapi id 15.21.0569.011; Mon, 2 Nov 2026 14:00:39 +0000 Content-Type: text/plain; charset=UTF-8 Date: Mon, 02 Nov 2026 23:00:36 +0900 Message-Id: Cc: "John Hubbard" , "Alistair Popple" , "Timur Tabi" , "Eliot Courtney" , "Zhi Wang" , , , , "Alexandre Courbot" Subject: Re: [PATCH v2] gpu: nova-core: gsp: cmdq: reduce sleep delta in wait_for_msg From: "Alexandre Courbot" To: "Danilo Krummrich" , "Alice Ryhl" , "David Airlie" , "Simona Vetter" Content-Transfer-Encoding: quoted-printable References: <20261102-cmdq_wait_msg_timeout-v2-1-50bc4534b659@nvidia.com> In-Reply-To: <20261102-cmdq_wait_msg_timeout-v2-1-50bc4534b659@nvidia.com> X-ClientProxiedBy: TYCP286CA0347.JPNP286.PROD.OUTLOOK.COM (2603:1096:405:7c::7) To MW4PR12MB6873.namprd12.prod.outlook.com (2603:10b6:303:20c::17) X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: MW4PR12MB6873:EE_|CY8PR12MB8195:EE_ X-MS-Office365-Filtering-Correlation-Id: 8ae0af86-a282-4a40-8479-08df38e9ad36 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|10070799003|376014|366016|1800799024|23010399003|10067099003|18002099003|22082099003|3023799007|56012099006|11063799006|261021121427099003|261022075727099003|261022105027099003|261026121527099003|261026140227099003|261022115727099003|261028144727099003; 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:MW4PR12MB6873.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(10070799003)(376014)(366016)(1800799024)(23010399003)(10067099003)(18002099003)(22082099003)(3023799007)(56012099006)(11063799006)(261021121427099003)(261022075727099003)(261022105027099003)(261026121527099003)(261026140227099003)(261022115727099003)(261028144727099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 2 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?WllzZnh5ajNHZEdud1BranZFbGZHcmMzbmo0TEN6VCtPTkRqUm9Oejk5bG1T?= =?utf-8?B?b1NlLzI3dkNOUnRiaVYwUVZaZUdGN3VZbWVIWVRIdmxWdTc2M2MyVUpqZFQ2?= =?utf-8?B?R1FLY2NvWVE1N01CTGZrVHVnd1hqVzNvZFJROTdhOC8wd0lCSjM1L0NlZTFy?= =?utf-8?B?Qkdoa2JYck5pL1JKakp6WDFHQjZlNWFLL3VyUFRnbjF6M1RheTMwRzg5UUhu?= =?utf-8?B?UjlWNUtBQkIzbzU3YnZPdHVjUTRBVjZMc01CQU8zTXEvRnZtQzlnSTNnd29o?= =?utf-8?B?dElyUU5RTzQvSDB0bWNYVTNZRWU4dTBoV3p3TDVVd0pOUU5aR2MvNkM2RGhI?= =?utf-8?B?N04vU0VTWVdTSEV6cCsyUkFqc29KZEpDSXRWTWgvR1VxTzFGZTJNZkdVKzhw?= =?utf-8?B?TVVwUlQ3RkJDY0FZMzNvbmJiZDExVFZiem1WVE51eG5rSDZHNVAwb1dhVitm?= =?utf-8?B?K0FtZ1FEb0VJUE1CTWRRZDVrcFk3REVldjQ3WDgrb3RQODdKS3A3Y3hVckVj?= =?utf-8?B?bnAyeDhSMjdUZTVFcEFqVER3TVM2dmc2WUZSYWozeXM5Y0tIeWZZS2dLRHhN?= =?utf-8?B?Y3JmbmROckhma05YOVczMmU4NjNlSVRKOUp3WGdUajVzdUd1dm0yanA1K3BF?= =?utf-8?B?VFZLMDdKOW5xeXlHZTJTMmZ5V0JKRUhLM1JZWjhWdWREVlIyR2prMDVLQ0ZY?= =?utf-8?B?Y210ekNHYUhIZksvMFdIOC9POHk3VVY5aGU2dzA3T2RqNi9IeEJsQUtXcUhT?= =?utf-8?B?eWI4VGRUYVVpcjVFakNacHhUVkx3aU5SYXBqWHRZelNmSENGdmgxU3pHY2t4?= =?utf-8?B?TWpONWhyYXpuYkd2QThSMllXL3JHMW5ZcWxPWk1JYWJQeENYOE9oaHVIbk1R?= =?utf-8?B?bzF5N3RTazd3c0dIaHFYb0cwMk1XWlI3YlNWdkRsTjIzaXljb1JSK3JTNTFZ?= =?utf-8?B?TktnbGZJcHl3U3RtbU96blN2NVVIY0JHZEFYTWVEeFFmeUh4YlFHQ3JqSEJY?= =?utf-8?B?Wkk3eDFNcTZwV3kzNjdtUitnM25ZVGVWRWpSclJoSS9ad3oreWt2aTVrUDhk?= =?utf-8?B?TjNWaUdPczF1Vy9Ld3NWWHZGMzZVOVBjTmlFR1lNRmxBVG5SMThaT2dLQWo0?= =?utf-8?B?THJLNmR0cnR0NFRxR3g0TXEvYWk4MXMvNE53bUNNa3c1Y2ExTnJVSEM0OElN?= =?utf-8?B?VkQ4TlBGMEdrTFNRNWRKQUF2bVFVSGRLVHc4YXJCTHdMZzZTQ3g2eE4xU3Ir?= =?utf-8?B?elVCeVBiczhUUkxHSWZOQUg2THRReHFXRm1PeW9tRUVKTGhOMGM1a0kxTm5X?= =?utf-8?B?SXZFaHZVR0JRcWdIaFFpU3d1ZWxha21WZzNwamI5V3RvNDg0SlFkSkE3aHpE?= =?utf-8?B?RGEwUGhHaXhnSXBjT1RTRU40OUJ1ZS9TUmJpQ3R1ZHI2bEZtbnlhRXIvdU9Y?= =?utf-8?B?UzFRZ2d4R2N5Q1pLLzVtK1VKTldKSi9VRmRzUUxGMTZKM0ZReENROXdJZ2ZB?= =?utf-8?B?a3VrRU4rVGlnekNuQ2ROQUxTS1FDOGV1UWVLdVFETWtJNmhCNTUzQVo2MVNK?= =?utf-8?B?dCs4cXF0KzFmZnBGSGFzdWMzNEVFcWdRc2Z4WHNENFJuM09rMi9relhQRGpZ?= =?utf-8?B?eExYVnp3NzBwa0pTZE5rVXNiTmF4Vktjd05aZXYrdFc0NFphY3JCK2NwM1Fm?= =?utf-8?B?bnBwNlRaL0tlUlM0SjJQZ05DaDR0UEFIUDREdURJNkZKWHA5VzIrVElTZFJE?= =?utf-8?B?WXJYY2t1Unh3OGVDNmlxYlRBL29QWjBUemVvT0s3a2NkN3E5cXJoQnEyTStG?= =?utf-8?B?YnMrQWVyZUNBUzNuZ2R6WUVJcGo2YXAxRDNVM1YzbEQ4c1JyOTlZaTdXeDFH?= =?utf-8?B?Z09aZnF4QkM3eFArWXVUNm9hV3VDWCtRd3AxNEZQQldXei9ZVXN1bXhTdTZU?= =?utf-8?B?NzF1MmZFMmROdmRrbEZDSjd3NjFoY0RBbVZlR1BuUWZ5bm9MaFZLbTJyRUdD?= =?utf-8?B?TUNrbGJQV25FWExDaTBwaG1wUkpGemN6Rk13RWl0WlRwMzJwUjhvOVVlUmVP?= =?utf-8?B?OExEYmxDYnVwekFlblh4M3Z2UUxIYnJkcWVYVERzSHRma3kwSFZ3R2daOUZr?= =?utf-8?B?c2pNQXExbTliTnNXM09LZWUyODBTL3FpWHZidHloNnV4N2FXemFZeDRBUjZK?= =?utf-8?B?dkZFWFRMWXA1NTNGMGtxb01hVFJCSG5aTHQrRkNaZ0RLL0cyWGxVNVh1SmxK?= =?utf-8?B?RUhNUHYxRmRHdndMcHpsRlREd0czb0xZL0YzNUFnRUtxZy9pc090eEZVRHlZ?= =?utf-8?B?eldXZGRTdHM2MkpuNVQ0NDNINmhuUHNlcEtJWmN2clNoRVVuRHJtdldSWjFu?= =?utf-8?Q?9hRXUG4BqZFOeGj+WSEWeaXcKPkJOkA8XUV632E9+r1Cu?= X-MS-Exchange-AntiSpam-MessageData-1: 7q4blQ16el0JPQ== X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 8ae0af86-a282-4a40-8479-08df38e9ad36 X-MS-Exchange-CrossTenant-AuthSource: MW4PR12MB6873.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 02 Nov 2026 14:00:39.6853 (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: P4YIUYYgsBntulCD7uxWAG1X+JxxuiSgE6le083HIqHQPhkwGJO3BGLr3GXbsEn8EAMCcvDazc+YQienZuDtCA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY8PR12MB8195 On Mon Nov 2, 2026 at 9:30 PM JST, Alexandre Courbot wrote: > If a message is not immediately available on the queue, `wait_for_msg` > sleeps for 1 millisecond before checking again. This is 3 orders of > magnitude more than Nouveau (which sleeps for 1 microsecond) or OpenRM > (which does not sleep at all and busy-polls) and is way too much, as GSP > commands are expected to be processed much faster than that. > > Reduce the sleep time to 1 microsecond. This effectively makes `fsleep` > busy-loop with a call to `cpu_relax` afterwards, keeping latency to a > minimum. > > Signed-off-by: Alexandre Courbot Pushed to drm-rust-next, thanks!