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Fri, 24 Sep 2021 00:17:14 +0000 Subject: Re: [RFC PATCH 00/13] x86 User Interrupts support To: Greg KH CC: "Hansen, Dave" , "x86@kernel.org" , "linux-kernel@vger.kernel.org" , "Luck, Tony" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H . Peter Anvin" , "Lutomirski, Andy" , Jens Axboe , Christian Brauner , Peter Zijlstra , Shuah Khan , Arnd Bergmann , Jonathan Corbet , "Raj, Ashok" , Jacob Pan , "Kammela, Gayatri" , "Zeng, Guang" , "Williams, Dan J" , "Witt, Randy E" , "Shankar, Ravi V" , "Thomas, Ramesh" , "linux-api@vger.kernel.org" , "linux-arch@vger.kernel.org" , "linux-kselftest@vger.kernel.org" References: <20210913200132.3396598-1-sohil.mehta@intel.com> From: Sohil Mehta Message-ID: <783bb314-ecf4-2a46-6baf-72758586123e@intel.com> Date: Thu, 23 Sep 2021 17:17:12 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0 Thunderbird/78.14.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-ClientProxiedBy: SJ0PR03CA0300.namprd03.prod.outlook.com (2603:10b6:a03:39e::35) To BYAPR11MB3320.namprd11.prod.outlook.com (2603:10b6:a03:18::25) MIME-Version: 1.0 Received: from [192.168.86.37] (73.222.31.188) by SJ0PR03CA0300.namprd03.prod.outlook.com (2603:10b6:a03:39e::35) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4544.15 via Frontend Transport; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?Y2VnRzJ0L2wvOGVXUXZtREZ4czVaYlNWNVJ0Q09LZWcydk5nbWYxUXl5QmZR?= =?utf-8?B?dXpySDNFZy9qcWxXamhoU0ZaQ0VnVk5Ga1lnRFk1WlpndS9LQnFUT2M1MU42?= =?utf-8?B?bzNGRDA0aW9lanZ5aFU4d29rOVo1SFJaRWVLYnZkVEZnR2FKS3ZyUG5mTVMy?= =?utf-8?B?bGZRMWtTRUE3V2hXWVpNaE5NMUk2MlNvR0s5TUwwOHdyRE9sYUpZZU5WTHN0?= =?utf-8?B?TUJxdGYzN0FIUzhqMkhrZTQ0ZE43b1NQeXJRd0gwcmNpT25Eb0xrWW9WZ3I0?= =?utf-8?B?d1FMSmwxY1ZlQ3d0ZW5SWEN5eFQxb0F6cURmT3Y4dFI0TnpTeU8xVkZ2dTJq?= =?utf-8?B?OHhoVDg5U3FqR2FkbU1WUWFOMXpsMkg3djV2WFNmcEl6UWh5SVM1Ukh2Zi80?= =?utf-8?B?SnNIL251Qk41bm5Ncm90WHByeE9aTHpSQnB6RHVwL2xYbUdSQkRVSElBUkxq?= =?utf-8?B?b0RNZzkyNnVUdFpTMjJRTTlaUGkxRXU2dVM4MVN4ZEloam5aeHRybkdYb0NP?= =?utf-8?B?NENtUjlobmdYZjZpK0VJL1hQOXhBaEFXUFZvcUJNT0ViT1cwdzRVMlZEV2dk?= =?utf-8?B?bjRXOXAwejZCbXd3ME8wSWdUMTE1TFdRdzhVOXl4eDBYTnhkWXpMWjBtVWM4?= =?utf-8?B?MHUvSGNvTkFSd25OK3QzQ2liQzE0SjJOcDdtZTJvTGxra3hid2pwVm4xRWJI?= =?utf-8?B?cW56Z1AwNS91TGVoM0xhUVpiVW9TcnRPYmEyZVR3c3NDa1hNQmQyaGYxSEdX?= =?utf-8?B?U2tJSkdWd1ZSSzFjVGNFaEFCQmxHczdubXlJWGtkUlNSYm9MdUhPcm1TTk5v?= =?utf-8?B?K2tING5yWm5DQzFSdDE3UkIzMXVhbDJYQXhzMDdxVm9GejRYY1MxSytPTHUz?= =?utf-8?B?a1pHd1hqbHZVK2ZLR055OTN0dTZMSzc5MFNtV2dlUjBsZ0MydVYvcTlkQ1or?= =?utf-8?B?bnhMK1FUalJPVXY3Sy9SVDJSdWRsaG95amk2Njc4VUNmWEtjZU5JSUdSanU2?= =?utf-8?B?dzFIZFRyMnlaQkxqZTdtb2IzY2NReGlncVdxeHNvZ1VWTXdodnNvd0N5WnhL?= =?utf-8?B?S25LNUU1dWlLVUxLaWh4UnJNbk8zU3RkM1JEemEzYjNiK3J3UFI3Y05SK2Z0?= =?utf-8?B?Z2F3NG1ySlV0OUpWcXNuSHVRREdKUmU2STBUUHZ3SEhSRm1qZytHQ2JyUm15?= =?utf-8?B?eElTb1hSMS92Y0ljRlFCSmtnZ2Z3aXFxVkg0VTcydGdmSnBYU2tCTU9sL0w5?= =?utf-8?B?am53SHczSW1JVE5vWUJUV1FzendLZEQxcUxhbjdYZmRIbjJZZzJxVWFHSE5L?= =?utf-8?B?M05Ib1lNYTNCbDhZWG1kS2U5WXVrdXltTWVTKzdMTFowSmdpOThDUjMzcHZP?= =?utf-8?B?RFhLdGxOaUJDblUwMGhNTWV6bDJKTjM4NFlVSXBYemdhVHNITkhYOFNDeDM5?= =?utf-8?B?dE9vRVlyRnk3VlVTMkNkWTRzei9uRElMdE5HYndFOHl2Sk1ZcWdPVkw2WHdJ?= =?utf-8?B?ZnRPN3dUeHVjOGxhT1pCN1pRc2U3OUxvc0tmeUpnekxjNU1rUVRTVjFPS1ox?= =?utf-8?B?WTdTTDJkR2NzTlRidjlXVHhBNlpWTmx3NEtsVklienphalhCZFlXaS96bkE1?= =?utf-8?B?aVVDdVIzTjI5bVBudnhKNjQ4V0FTMHZoNUd0dERIa204cHNQWFE4ai9XNytW?= =?utf-8?B?M04vYnZja1EwVndsZnNvTkxSSjN2MDR1WUtrQ3BxNmZhSVhlUitwaFkwWGRw?= =?utf-8?Q?z2wgfLpPldcRBXdVFsP0IjmTK01CCee4PG6eeGm?= X-MS-Exchange-CrossTenant-Network-Message-Id: 6f18fb8f-a9f2-4929-bf88-08d97ef0a8ee X-MS-Exchange-CrossTenant-AuthSource: BYAPR11MB3320.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 24 Sep 2021 00:17:14.3993 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: BTz+jsketzd5mFnbrjhz9zuLFKZfehK4Wad3pu0RfrnWe88VGW++VbMTyxWzyc3RxHFsgLQbXYTi+vPK4SQszA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BY5PR11MB4419 X-OriginatorOrg: intel.com Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/23/2021 5:19 AM, Greg KH wrote: > What real workload can actually use this? > I missed replying to this. User mode runtimes is one the usages that we think would benefit from User IPIs. Also as Jens mentioned in another thread, this could help kernel to user notifications in io_uring (using User Interrupts instead of eventfd for signaling). Libevent is another abstraction that we are evaluating. Thanks, Sohil