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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?SmlJMDZZZ0lJMkZYV0FxaitCZjV1dVF4N29JUVpXNzFiaHJnSC82WXdKVTIr?= =?utf-8?B?NU11UHE0RTNZMFlyOWFkNGVFaXRvYmF1aFIvNVhDQnRqaDMyN01MUE9YbTJi?= =?utf-8?B?SGVhL2ZXSk9NaXlRaFRSSTE5MjloK2ZFcG9ROEhIbHkzcWtiWXA4L0V0Qmh0?= =?utf-8?B?SEUvb0pNandLR1MzeFhiQmdsMnVZaHB0ekdxMXRTUWFaUjdNRysrRlhUY010?= =?utf-8?B?K3VORS9JZUVBUmFCTnViYWdpaE9GRHpSdjJJanZXajUzekV6YjI3RDQxeEJM?= =?utf-8?B?QVgrTTAwRVllQTNZdWkzendzeWdRNWRtUTV6MFZrZ245MEloelByQXk0enM2?= =?utf-8?B?ek41QmRVNHF1Z1A5Z2FxRmdSbnJqU01JSEJDT3E5NURxUnVvbjhGWk82K3gv?= =?utf-8?B?d0x3cjZKMXNjS21vOVRFM09lWXdsSml0TS9pSi9SSTlEY2ZCSTR1UTV6N3RL?= =?utf-8?B?UjZIcHNPQmxYQjlWRU1LbjRwYXJzYmVBK21TNGUvbXBCcVlpRWw5L2loMVRV?= =?utf-8?B?V3hxYXlMbjRsemQyaGdLT21iV2hvbTZMR01oZVdMbm8wM2lmbVZkVWNEM0Z0?= =?utf-8?B?NHNkZDZ1VzlScUdWQ3dtT0R3L0h1MUluMUxqOUhTenlDdU15a3JDZzdZam9l?= =?utf-8?B?ZU4vSnEvUEtsVjZJVmZBd3RCdXc0eG9ITDFtQVBBcm5aeEE2WFRXencvNjlE?= =?utf-8?B?cEM5MGpyWmJkaDl0VDVKT2JkQlZ6dlprZ3BHS3pvV0t4R0w2M1k2QzI4R3pS?= =?utf-8?B?OWpNZzUzQ3FPV1dUamRCVjBFZ3gyMUI4aW9CWkx0TzkvSlpnemh5YlRSL3Vr?= =?utf-8?B?WSswbDNhRitiUm95b3pOY3U1eEZQZEthNVB4V2FCa0dWcDBRWEVVejM4QnBp?= =?utf-8?B?UGNtK0llMlR5QytERC9hdE4ydHlBRS9kUGZnSVVqTlhQRitOUURLb1UrK1Vz?= =?utf-8?B?UERhSUw5dkVaRCtUU2NvcnNpSzZKRlRYZlh4bER4bWdYYmVSRWNSM3ZPblgr?= =?utf-8?B?MzRESzY2WkxUY2hjYzhFYmdIQjFvS1VxazZCR1RmQXNQYVpmcXk0c0ErUVpo?= =?utf-8?B?V3dMelZUSXlYOC8rNGplQmV3U09mSHBmZEtMUHhoRGQxS3VyRUpKaUdOWjQz?= =?utf-8?B?UnNDSHVoc29YODJqbTNVTWJ4QzVqYkpCR0dTSVp2UTVZalMvZHM1SEQrWWFQ?= =?utf-8?B?cU9YK1VQblRvNU5pVEQyQkFvZ2hwaXhYenJNNlVqNTZMZDFRSERUcTRGbzcx?= =?utf-8?B?NmNWV3NQUGxoYlRrU21Bc1Z4S1R0Z3hSVWlqWHRDU2UwR1dQUjhpQnpwdk9E?= =?utf-8?B?K3dReWlOUmdMbkVwWEJnTjVZYU5yN0Q4MTllMjI3NUJReElaRDkycSt4SkdB?= =?utf-8?B?NWFReVdNempCOVIzSFRmdDRWSFlkaEI0TkV5Mkluek1LZUpOYzJCWlg5MS84?= =?utf-8?B?TW5ROTR1YldoMmY5aE1nUEQwOTh3VENQMFFGWDhoZkJvK3Z1WWVLRUlvaU1R?= =?utf-8?B?bnFmaW03YktLTmsrYmZYamlZQ0Y1ZDU2a0RRanRWYUp1dTRlbThOdCsyZktM?= =?utf-8?B?WTErS2lxcW82T1hxc2crdnBoWVQ1N1JzTURTTW83R0N5d2lValJqaDAyNDR6?= =?utf-8?B?NWlhcUxWdHVGZnlVTVFUSUhlNXM2TkgzaFNTenFOR1BFYWU3TUpBeXJuZ1BR?= =?utf-8?B?Zmh4eDViL2NYT2NIUVFHWXh1LzhMWUhibXhua0ZUU2ttMWZ1Y1hPdEhyOU1z?= =?utf-8?Q?wKPOPV9u5xPNefxJ1ITg4ehACtyxL5DS6JyKL6w?= X-MS-Exchange-CrossTenant-Network-Message-Id: 3fecc8be-3fcb-42ff-86c1-08d97913071b X-MS-Exchange-CrossTenant-AuthSource: DS7PR03MB5608.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 16 Sep 2021 13:08:08.2370 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 335836de-42ef-43a2-b145-348c2ee9ca5b X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 7gJSgvcInAPwws0oYCJ+al1VIw5sz5OlLGaCh4m8Ny61bl6GfagTBhgdshexZP/VSbq8Ewvjyk53QOTqlSXvpA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR03MB5289 X-OriginatorOrg: citrix.com On Thu, Sep 16, 2021 at 02:30:39PM +0200, Jan Beulich wrote: > On 16.09.2021 13:10, Dmitry Isaikin wrote: > > From: Dmitry Isaykin > > > > This significantly speeds up concurrent destruction of multiple domains on x86. > > This effectively is a simplistic revert of 228ab9992ffb ("domctl: > improve locking during domain destruction"). There it was found to > actually improve things; now you're claiming the opposite. It'll > take more justification, clearly identifying that you actually > revert an earlier change, and an explanation why then you don't > revert that change altogether. You will want to specifically also > consider the cleaning up of huge VMs, where use of the (global) > domctl lock may hamper progress of other (parallel) operations on > the system. > > > I identify the place taking the most time: > > > > do_domctl(case XEN_DOMCTL_destroydomain) > > -> domain_kill() > > -> domain_relinquish_resources() > > -> relinquish_memory(d, &d->page_list, PGT_l4_page_table) > > > > My reference setup: Intel(R) Xeon(R) CPU E5-2680 v4 @ 2.40GHz, Xen 4.14. > > > > I use this command for test: > > > > for i in $(seq 1 5) ; do xl destroy test-vm-${i} & done > > > > Without holding the lock all calls of `relinquish_memory(d, &d->page_list, PGT_l4_page_table)` > > took on my setup (for HVM with 2GB of memory) about 3 seconds for each destroying domain. > > > > With holding the lock it took only 100 ms. > > I'm further afraid I can't make the connection. Do you have an > explanation for why there would be such a massive difference? > What would prevent progress of relinquish_memory() with the > domctl lock not held? I would recommend to Dmitry to use lock profiling with and without this change applied and try to spot which lock is causing the contention as a starting point. That should be fairly easy and could share some light. Regards, Roger.