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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?9zXwe+s3C5JYmrI4FEYJLBE/aJM9JRx05TGSu0+2S2RDJPnT1GP1OsKzAjMq?= =?us-ascii?Q?CWWXE13K1eXOovJepKb538uGa4xa89cUa1jZ1nFtJvgW/CHz+bzaWyzjpE57?= =?us-ascii?Q?L0bYdKANyC8j3hug5M5tE8JAii45k4Fm5KJBShwoNdxTXfqaBBKqrlH5wQ+d?= =?us-ascii?Q?Tc6Oz6kA2ZUJK9WT3M62MKfRZ3anlWOyyftTQjv0r1lmfeeHYH43tLcB+hFj?= =?us-ascii?Q?aF9vJPXNuCga8KCo7nw6J60b3Bkr0Hay+fFFz0SH0qElxq5cOiLZ8Z4fMMhG?= =?us-ascii?Q?CtGw/6680gjBeMxJ86Vr2003RC+0QelLMrQ57IPqvYNGJSQ2T0DcBT5GDXgN?= =?us-ascii?Q?schlzDHQptt4yZnGyfmOOpJsh2cOeg7PH/So4tizpWXdxcQEon28sSHFXGAV?= =?us-ascii?Q?sZRjOh1zAHUQwEU/PxrrD1u1lw7NEhNUQRjZnSUlrtsTCpm3wVXjfRmz221j?= =?us-ascii?Q?57zDUUkD89JnauBMRx5X91p2QUvLSjqNiKFBW5gm2IdLVW63hfrk6XR8MVpJ?= =?us-ascii?Q?X8V8WXobvYkg8SpkOdrwEgFoquxHFnc2jUn9alhORtSyF+elv79H3ubY28cu?= =?us-ascii?Q?TM1RvJSUag80GI4FUjhtzsevQ7eL3VOCIsgAGvoUko1f6WbuA7lZuqSHGyaH?= =?us-ascii?Q?2N9n1+3C21ZEcnoLsZ4EGpANQTGMQ/jLgQDUJZLI0q6TH5UbcBZ7CyCMiQ9G?= =?us-ascii?Q?1QC9zBIIAGYBbGKOv9xV2d4FMXfxeiZAiK7ZpFSg54maOdH/eZzKuePbRT4I?= =?us-ascii?Q?zLgTgWpjd0DLSorRAJxf5xudeMPyqUwfLC+YEpQ/bZiGMmgHFu+WYQD0aSaF?= =?us-ascii?Q?+oPUcDne/s/dKw5sy40apmhDKBmVywFbarWnOeGP/A0q3B0MZKaJQ3JiKrml?= =?us-ascii?Q?Uso+/atkOa/AKegrruq1XCVtmFVOYmTX0gZT9TXg9RBlN7TYB9uG0jL1IPij?= =?us-ascii?Q?Jmsu4XM8KxQEm0K9XRYKeh1czwsFfHZSG2IywgqoGc5F9ovPVH3Ky8h2C4Ja?= =?us-ascii?Q?gCZmVJNg+jloQnpJltNTKfOCxIjywJJMLGXlp4kcLDrETlaJY+Q5qB9C9WXk?= =?us-ascii?Q?m5K6AAudNGxYlynin7H8jbJKq6HVHxSUOL1raOlaES5o2RJzI1flqmUcAq5o?= =?us-ascii?Q?I+QM84wj8k80J5sv3XPqt72OxwXxsZ7Fp7q676ZF8cSgGooShxYwp3lOVW13?= =?us-ascii?Q?DMloc/rv/tAUD86JnDugF6oNlnhkggnETakrjiKqM0vMvYFp2KnSuX8/fBVv?= =?us-ascii?Q?GTP4QTH9bctqlPICiG2wrktGSqbf6zLHNBwgmKI0cHDFh/GcTYsTtR81RQ8p?= =?us-ascii?Q?cE3xu/bQ8Yc9tA9Tmq5hnRYY6gVZhC392fFp+42Zh010bM6FQJZHEgKPPifb?= =?us-ascii?Q?PafiiYKhB21kI7PsjroWiObAu/L/A4A6Teg+vErIQJddLn0viYkqUNvTMnU3?= =?us-ascii?Q?2JC7fKnNLlx6xPsoRttKX2z5KNcqMOKDpb+lVGne9JXwzBv/MpWYXK1pd801?= =?us-ascii?Q?Ojc0K/tQ7gUL6LCfoXMcOWe+kmnGMQInDwq+eoR6sNfGwIQ9uwlNRt2L/FdI?= =?us-ascii?Q?3JaE/ANgIhf4CQ+reNfLyWYTDc0p4svGnkkJGzsMvRPqmwrpmdVxtFBmOIsO?= =?us-ascii?Q?SgT+T6NacRNlbKAg9l/8Oi07kRDmqlcyhvwUZG1mEfbzTLYNRo9NiI68wdgF?= =?us-ascii?Q?hqf3LR+i4HfLQJmQd7gA5M6rwGNCmbpiOHct4f8ywuSGlEMava3h5FE44ksB?= =?us-ascii?Q?R945NE425Q=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: efcbcb53-1e3c-42e6-6543-08dee2753b60 X-MS-Exchange-CrossTenant-AuthSource: IA0PR12MB8374.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 Jul 2026 13:30:26.9943 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 9Ajz59PDcbHX1M7n0ZcEYT2cc8Ev9Q9Dt3M3klfPli2Zt6j9ocI4kWXin2U2/Avj X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS0PR12MB8562 On 15 Jul 2026, at 8:40, David Hildenbrand (Arm) wrote: > On 7/15/26 02:59, Zi Yan wrote: >> On Tue Jul 14, 2026 at 1:30 AM EDT, Alistair Popple wrote: >>> On 2026-07-14 at 10:10 +1000, Balbir Singh wrote... >>>> >>>> I had a patch to add tracepoints to the code and some of that instrumentation >>>> included this data. A combination of the trace points + hmm_tests will help us >>>> get some data to start with. >>> >>> But hmm-test already has a nice bandwidth benchmark :) We just need to force >>> the slow path. That used to be easier before I simplified the trylock handling >>> but with the below patch applied I get quite a lot better perf from the >>> optimisation. Note the patch isn't entirely correct as it assumes any locked >>> page was locked by migrate_vma_collect_pmd but it's good enough for the purposes >>> here. >> >> Thanks for the numbers. If I read them correctly, the optimization >> has about 3x throughput of unoptimzied version. The optimization has to >> stay. >> >> I will try to come up with a fix that resets collected PFNs, reverts >> established migration entry along with putting folio ref, and restarts >> from the beginning. > > IIUC, with the page table gone there are no entries to revert. We only have to > take care of folio lock+ref. You are right. > > Which raises a question: how can the page table be gone when it contained > migration entries? Probably MADV_DONTNEED could clear them, followed by > reclaiming the page table, maybe. Yes, that is the case pointed out by Codex. Best Regards, Yan, Zi