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Howlett" , Vlastimil Babka , Harry Yoo , Xu Xin , Chengming Zhou , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Zi Yan , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Alistair Popple , "Matthew Wilcox (Oracle)" , Christian Brauner , Usama Arif , Yu Zhao , Baolin Wang , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20250724084441.380404-1-link@vivo.com> <764c48ad-8869-4f69-898e-0a1c58684f7d@lucifer.local> <40cb7d64-0b90-4561-8e10-06a808a2766a@vivo.com> <87bjp93vb6.fsf@DESKTOP-5N7EMDA> From: Huan Yang In-Reply-To: <87bjp93vb6.fsf@DESKTOP-5N7EMDA> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: TY4P286CA0091.JPNP286.PROD.OUTLOOK.COM (2603:1096:405:369::10) To PUZPR06MB5676.apcprd06.prod.outlook.com (2603:1096:301:f8::10) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: PUZPR06MB5676:EE_|PUZPR06MB5537:EE_ X-MS-Office365-Filtering-Correlation-Id: 6ff11499-329d-4dec-1edb-08ddcb1d3386 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|7416014|52116014|366016|1800799024|38350700014; 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Additionally, the flame graph shows that the proportion of >>>> remove_migration_ptes can be reduced from 80%+ to 60%+. >>> This sounds completely contrived. I don't even know if you have a use case >>> here. >> The test case I provided does have an amplified effect, but the >> optimization it demonstrates is real. It's just that when scaled up to >> the system level, the effect becomes difficult to observe. >> > It's more important to sell your problems than selling your code :-) I'll remember it. Thanks. :) > > If you cannot prove that the optimization has some practical effect, > it's hard to persuade others for increased complexity. To be honest, this patch stems from an issue I noticed during code review. When this patchset was completed, I did put in some effort to find its benefits, and it was only under such an exaggeratedly constructed test scenario that the effect could be demonstrated. :( The actual problem I'm facing has been described in other replies. It's actually about some anonymous pages and fully COW-ed pages, but their avcs haven't been removed from the anon_vma's RB tree, resulting in inefficient traversal. Lorenzo has mentioned that he has some bold ideas regarding this, let's look forward it. :) Thanks. > > --- > Best Regards, > Huang, Ying