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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?DY9ZISJznPhGSJ8zBPGpIiSfkgHaV+EnwPpLbYm27VPN8IoPs02jWV+pftlT?= =?us-ascii?Q?4p3hhXPkivQBXsmyUSmUPGe6DYDOzPpY4AMaZAF4ykAh8Vmlb1gxjs2y6uoS?= =?us-ascii?Q?tx0atBgh1RP7YCfbMlr0qPHELK7VT9nQnYWIuHcwORk2be79XxaxwoQIyqYU?= =?us-ascii?Q?sR49bEOkQw0I/JzwU/4xM2he1KsCFMsnd/vA4iFQeWBStJ9QHCkwrdQf+f8B?= =?us-ascii?Q?91F3xmeU+uOWNNQSD5q3wcgXnpRo1Jx0sBOyh9yX3bjSKrWgnoBQvybMtdCS?= =?us-ascii?Q?am/7v1ej01h/GUC0X8Hrhl31TX1mEQMVZh9He4ENm0ZgAO3dH7cESiKrPegW?= =?us-ascii?Q?2cWRmC0RVmSEUn5vZATHeFpow7+YvJjKLm3jEsKU4JUwoGlWV7ODKHyK9Ppi?= =?us-ascii?Q?DBRoCGEnQNDoxlci7+bg3xw1HXyuCfwbsSWMfyFJylh/itJ73w76o/gysf9P?= =?us-ascii?Q?4oQprTy2UBb63t7PvY6CIf3DZLblWvtnblA7zAi2SnSYiovv/qd3gFbJXHL6?= =?us-ascii?Q?K2AVOfFDzatZem/NpuvihAkvyOg+SqcsP6KbhCk2KhgitkPaJfEE2lTQYcM8?= =?us-ascii?Q?OIPmZDoDEv9Lu28cEzLvizPosEc08RoWKHQChBhTa9gErFvFVnGkc5ZM3zqw?= =?us-ascii?Q?mY3H7+hUeczj0R1QHGh/doIAkWEskzCeuI9W8Lk/7qojsRKw0K5NwTtoeroU?= =?us-ascii?Q?KLPLUWXkhbaMnKMl4jFr+ncefImHnhrTxCSj2JyLSI8vcTfl82/1scpOcKp5?= =?us-ascii?Q?Qm+azpnK23AK66LRqPZ7qgN2e0rFiYvxdVJSlHA1+kqFqMGDJtYt00EmXbnj?= =?us-ascii?Q?Rkh2afiAgN9Cp0x5iUvNmv6RSKHdaXbr9nT3TThwkJec8z/lABICEx+GddWt?= =?us-ascii?Q?LL4wPd1flnJ95LD/AQP3SDv/FW+nk4ADTVvQzsWP+uX/c0GW2ViM3BndMGUx?= =?us-ascii?Q?60BbAPam42zzny3QbGKaQHHdivz71rYyQRLn2US/E7TMvhN7PqhubDt0YvN8?= =?us-ascii?Q?Wm96RFb6D8H2LYGE4WbT5vjkoORclaSG+ZVq5Kh1mwoKldlbDeNAG4mZJybm?= =?us-ascii?Q?/GXqGSai+lRD74yQ+ySobcJY3tkZsDnQH0v6/Q51PW2HFYlPNrg+5IhFJ2Y6?= =?us-ascii?Q?pNQ8x6dLMzJR+obUqa2C9aB+8KHiXIddJku1CxSdLZOmeP+3lAMJwt3fr3JA?= =?us-ascii?Q?6k5LD4nFU6lzZfvmHlQh3D/l2wJf6WM9F5Bwjj6mhII/dFBIhl53AnsYOF3h?= =?us-ascii?Q?yomRDBzGdclkLmg53UMSJySBW/DwbPvMIAw3vMEmwH7LtYkvANuDf9Hj5Lp4?= =?us-ascii?Q?D98RDlMk37SaBrx7Juu82QQnHrgjHsD7YREmsovezmR9dDDNQ6G1np3odt5z?= =?us-ascii?Q?R1ImXnlj+aRSvLeW6GlYWXsgMgMOUnmyEAQMBixIiAm9LshF5XCKcgke1vgy?= =?us-ascii?Q?5djzNRI9rBF0m926SOEm3yCIb+Iiu3msnwLGfP9dp8Vde9ce1/JPyG5K0V6X?= =?us-ascii?Q?FNedwK+WUd/CNQmeYXu+HwfL+e4lfnOjUKI33f9N2tBdNvu4gfl95KxBpemi?= =?us-ascii?Q?maqrThTx2TL2ySQmQPcv7TJ53HOahuNf36jQsnPcWaobU/vZo/D/a4IPNON8?= =?us-ascii?Q?1V7QbAttaTj24Nklgbkm7X4ekuVmaBBsBtzdVI6f07gy1lKsXVwkaSMxR90u?= =?us-ascii?Q?48ZSuhcnpBNu6FmjHQTEi3d0tAhtBElqCcamM48Ou7BoB+aC?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: bab25141-e792-4231-7973-08df077090c1 X-MS-Exchange-CrossTenant-AuthSource: IA0PR12MB8374.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 31 Aug 2026 15:00:15.9769 (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: WhIU4C1HGr+1FrP+daVcJZ0HGiGeAw6QgA0woRhsZ5V/tpTOqXSfiBIi0hD58/QF X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS8PR12MB333896 On 31 Aug 2026, at 5:34, Lorenzo Stoakes (ARM) wrote: > On Mon, Aug 31, 2026 at 11:20:30AM +0200, Michal Hocko wrote: >> On Mon 31-08-26 10:56:35, Nimrod Oren wrote: >>> When THP is enabled, set_recommended_min_free_kbytes() may raise >>> min_free_kbytes using a heuristic that scales with pageblock_nr_pages. >>> With MIGRATE_PCPTYPES equal to 3, the formula accounts for 11 >>> pageblocks for every eligible populated zone before capping the result >>> at 5% of low memory. >>> >>> This is reasonable when a pageblock is 2 MiB, as on common 4 KiB page >>> configurations, but scales poorly with larger base page sizes. With >>> the default arm64 pageblock sizes, the contribution per eligible zone >>> before the 5% cap is: >>> >>> 4 KiB pages: 2 MiB pageblock, 22 MiB per zone >>> 16 KiB pages: 32 MiB pageblock, 352 MiB per zone >>> 64 KiB pages: 512 MiB pageblock, 5.5 GiB per zone >>> >>> Consequently, min_free_kbytes can reach excessive and unwanted levels. >>> >>> Add an absolute 1 GiB cap to the recommendation, in addition to the >>> existing percentage cap. This bounds the automatic recommendation to a >>> sane value on systems with large pageblocks while preserving existing >>> behavior for typical systems with 2 MiB pageblocks. >> >> I would argue that the whole model of increasing min_free_kbytes for THP >> is wrong. This will trigger memory reclaim sooner and make the THP >> availability more likely but this was at times where we didn't have >> pro-active compaction and many changes in the compaction. So is this >> actually needed in general resp. only large pageblocks systems? > > Ohh even better :) > > I did find it strange that we increased accordingly. > > I'm more than happy to see this just die altogether if people agree that's > a sensible way forward... It sounds reasonable to me. My first reaction was that THP generation might be hurt due to fewer free pages. But probably the extra min_free_kbytes just moves reclaim earlier, like Michal said. After removing this automatic min_free_kbytes bump, user can retain the old behavior by setting a higher min_free_kbytes at boot time. Best Regards, Yan, Zi