Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [RFC PATCH 00/13] x86 User Interrupts support
To:     Greg KH <gregkh@linuxfoundation.org>
CC:     "Hansen, Dave" <dave.hansen@intel.com>,
        "x86@kernel.org" <x86@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "Luck, Tony" <tony.luck@intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H . Peter Anvin" <hpa@zytor.com>,
        "Lutomirski, Andy" <luto@kernel.org>, Jens Axboe <axboe@kernel.dk>,
        Christian Brauner <christian@brauner.io>,
        Peter Zijlstra <peterz@infradead.org>,
        Shuah Khan <shuah@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
        Jonathan Corbet <corbet@lwn.net>,
        "Raj, Ashok" <ashok.raj@intel.com>,
        Jacob Pan <jacob.jun.pan@linux.intel.com>,
        "Kammela, Gayatri" <gayatri.kammela@intel.com>,
        "Zeng, Guang" <guang.zeng@intel.com>,
        "Williams, Dan J" <dan.j.williams@intel.com>,
        "Witt, Randy E" <randy.e.witt@intel.com>,
        "Shankar, Ravi V" <ravi.v.shankar@intel.com>,
        "Thomas, Ramesh" <ramesh.thomas@intel.com>,
        "linux-api@vger.kernel.org" <linux-api@vger.kernel.org>,
        "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
        "linux-kselftest@vger.kernel.org" <linux-kselftest@vger.kernel.org>
References: <20210913200132.3396598-1-sohil.mehta@intel.com>
 <c08f38db-77da-c50e-23f7-b3a76688deeb@intel.com>
 <BYAPR11MB33203044CD5D7413846655F9E5DA9@BYAPR11MB3320.namprd11.prod.outlook.com>
 <YUxwuR4V+kwk1L34@kroah.com>
From:   Sohil Mehta <sohil.mehta@intel.com>
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: <YUxwuR4V+kwk1L34@kroah.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
Content-Language: en-US
MIME-Version: 1.0
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: <linux-kernel.vger.kernel.org>
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