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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?V1Z6MmlpTUJQcTZoU3JMajhsN2hoazM1QnJ1WHdvK2duMkxubU5ORFE5YTA5?= =?utf-8?B?RGhLQlNmYk1RVERBdmpRQU9YUHM4ZDlaazYxNTFyVEhCc3Bha2EzbEpVTG5u?= =?utf-8?B?bTZKUFhqMit6d2xLcTdaRUEvVzh0VTBBZktZNVRFQ2tGU0FINlI2cldnOEZV?= =?utf-8?B?bEYra0lIZkJXeXZKbGRDc3UvVUhLQy9xdVRacTJRUHlISFZIMlJHOUV6clNM?= =?utf-8?B?M08xNUdPbWE0ajZQVDRlc2tJM2ZGSWZwZVM3QzlscDRKUVZXVGJOQXZwS1N5?= =?utf-8?B?SU53dzd5OE9WeHBVQWRaRFpaSVVaY2kzWFFXOVZGdzY4Q0tRUWxORnE5clZ6?= =?utf-8?B?UFRGWXFlQkJ0TW1nZFpWVmRXaURic2dhMms4ODc4VTRKSDhDSmVEdFJHUGlN?= =?utf-8?B?YWY3aHVuS0YrdE9qRCtvUDRnMVo4ODlDWmlwWXhIVkVwZ0RYbzBSOWRSYkNx?= =?utf-8?B?bC8xeHppVFVPbHJPKzB4WXRzbDYzOUhnSERFS09uak5VOVAzOTZrQTlTNlJs?= =?utf-8?B?Qmh2V1FyWWxjczZhQlcvZ3I3YVc2OUd1RjFlRlIvV0pLNXJzTWJaa01MekNv?= =?utf-8?B?b28ySitwenRmQ1BMOGNmcUg0ODhURTJucGduem03Y2RISm5Wa0psZ3RZWDNx?= =?utf-8?B?TU05aThWNlBucWM1Zk1LS0tnMHZIUERxdUo5MHJ6VXpBVTd1b1JZeGNUUXZk?= =?utf-8?B?UXhVeXhSdXIvMWdLU3hSaGJodnFuS3N4SFR6K1E3N0hVMEF4cmVTdlB1ZG9w?= =?utf-8?B?U25xYWd1RFQrZzIzWVJwcHA4V0NOeFFnaU1NSTAxbkU1ZkNGbE04RWtLZWZl?= =?utf-8?B?WTNCNlNEcGFNMmhiTFlZMEhDYlFJa0wxejZybTVxLzhYd25OTnkxb3dSMUQ0?= =?utf-8?B?TVlqbnVDUVlFbGM1ZmQxdVFyakpWNFFGbkhORHUzaXBLTkMvQ3ZjWGd1MmdB?= =?utf-8?B?bzNVKzlZYmlxNVVFdFRzZkI2V0w4Z3R4eW9OaGpVZ245KzdDaTZYeU11ekVC?= =?utf-8?B?QjJVWFlvOHE1SmxWNmhYWmFZOEZMZ3Q1UUNrbENqUnFvbHRNMjZpWVFoY1lM?= =?utf-8?B?VThzT1BwMkxOYzVqOGRVYWhRQ0NUb2g2a0FJTjlQTi9ybGIvSkRKWkhNanFt?= =?utf-8?B?aEFOeXpsK29lbXpYUkF6MWFlaWxtODlBRHlwUW5yOTh6RGovQWg4aTFQRTRV?= =?utf-8?B?Uzk3Mi9WTWI5TCswbGpFRzVUWFNzeHJuQmxjTEJ4elZiVjQ5YWZPSjl6Y0RB?= =?utf-8?B?ZVlhVkUzYktWRFFhN0JUWTV0MGo1d3N6endHcFJZSWp2T3B5OEdSQWNHS3lw?= =?utf-8?B?QWJ1ZHpmWGlWWjY0bldIM29UbmovMUMycm9YQWZGNmhoeCtuOWdMeVh0ZWZZ?= =?utf-8?B?MTlkdDJsaE9mcFp6RjVrRHMvb0YxOVZ0M3RMLzNNM1hpOE5XWFlSZ1FzWW1N?= =?utf-8?B?dHArQTdDcHZIYlROQi93ME95ems1b1ZxN2NvN3gvY1BQcjZsQXg5MW1jUjQx?= =?utf-8?B?TGJBaFhzbGJveUZyRGdZQ2taNktPZVJBUzB1Y2I4T0NMM2xYVDJPNmpUUjRT?= =?utf-8?B?Rks1Sm5ZVG93TWlNRmZodkFmQ1d3RDRNZ0xKeDhGa202Mmo2SkVlbVNlUkhs?= =?utf-8?B?T295Mm42Y0dTN0RWSVVwcTZSRE5jcitWamF5aEYxbitRbFkzZEV0Y3FDQWhr?= =?utf-8?B?b205bUxjL1BEQWdIR3lyUWFmd1lRSkJsWTAwWXlNVnJQcUw3cUkxditsNDVt?= =?utf-8?Q?MtW9e9Rt5ZW43M9kqVZGZIQQ9MQtjDKRUIWGB7h?= X-OriginatorOrg: suse.com X-MS-Exchange-CrossTenant-Network-Message-Id: 7b150297-fbec-40c9-0402-08d979ac6da2 X-MS-Exchange-CrossTenant-AuthSource: VI1PR04MB5600.eurprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 17 Sep 2021 07:26:13.1375 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: f7a17af6-1c5c-4a36-aa8b-f5be247aa4ba X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: KoCoWMBA/jKtjtDDuKZ1uXUa9LE8dCMxvU3IAU1tUwgFyOnbm6zwlkdI0V1ABAxXe8ivKYWQOlhk4MRgbrzMTA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1PR0401MB2608 On 16.09.2021 17:04, Tamas K Lengyel wrote: > During fork reset operation the parent domain doesn't need to be gathered using > rcu_lock_live_remote_domain_by_id as the fork reset doesn't modify anything on > the parent. The parent is also guaranteed to be paused while forks are active. > This patch reduces lock contention when performing resets in parallel. I'm a little in trouble following you here: RCU locks aren't really locks in that sense, so "lock contention" seems misleading to me. I can see that rcu_lock_domain_by_id()'s loop is extra overhead. Furthermore - does the parent being paused really mean the parent can't go away behind the back of the fork reset? In fork() I see if ( rc && rc != -ERESTART ) { domain_unpause(d); put_domain(d); cd->parent = NULL; } i.e. the ref gets dropped before the parent pointer gets cleared. If the parent having a reference kept was indeed properly guaranteed, I agree the code change itself is fine. (The sequence looks correct at the other put_domain() site [dealing with the success case of fork(), when the reference gets retained] in domain_relinquish_resources().) Jan