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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: YvvhR1mleMaQitKxzHE7hB2/f/q/hg/pk5XivJdcCpBF42dc+MH/3nsM1yBC8741Kzj/Jdj1L3U3/fgaZGnv6IqOkw9ObZgqRPQEIhTmMcUHZxUj1N7NsY0PZECD0VDDyHazdv36yqHnHoVAxyOJcYIKsIg/dtDU3QvSt9s0eI6QC6K97Q78ST5ROOe3p8aFJ+JtaV23Qn7mSJM9jl4sGOVKtA81IHjhy1IvlRX+UbzhwQi4h9oTXAoz/c0zkr1CJm9BYQl7xiPbYR37ZKuqsNfX3ufEvxGhuulS16sQ8oQd+NVOAyfc9vGOP/X1R4BD36GTSLPF1YmBzp9phdSrq9fbkQ9qvOeNzHnTSRyLHgnl/nGO4QHmGxUiQD1UzMC2zlDvpigVoD6DF0Oxy5QZQ/ts/s1spcJG0NERlvLG0ZuT/J3+Eo3Tk72IxH8U+xQo X-OriginatorOrg: arm.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 11 Jun 2026 12:13:41.3067 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 7cd5ee09-4d50-4481-661a-08dec7b2e046 X-MS-Exchange-CrossTenant-Id: f34e5979-57d9-4aaa-ad4d-b122a662184d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=f34e5979-57d9-4aaa-ad4d-b122a662184d;Ip=[4.158.2.129];Helo=[outbound-uk1.az.dlp.m.darktrace.com] X-MS-Exchange-CrossTenant-AuthSource: AM4PEPF00025F9A.EURPRD83.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI0PR08MB10992 On 6/11/26 4:56 PM, David Hildenbrand (Arm) wrote: > On 6/11/26 13:07, Sarthak Sharma wrote: >> >> >> On 6/11/26 3:31 PM, David Hildenbrand (Arm) wrote: >>> The droppable test currently relies on creating memory pressure in a >>> child process to trigger dropping the droppable pages. >>> >>> That not only takes a long time on some machines (allocating and filling >>> all that memory), on large machines this will not work as we hardcode the >>> area size to 134217728 bytes. >>> >>> ... further, we rely on timeouts to detect that memory was not dropped, >>> which is really suboptimal. >>> >>> Instead, let's just use MADV_PAGEOUT on a 2 MiB region. MADV_PAGEOUT works >>> with droppable memory even without swap. >>> >>> There is the low chance of MADV_PAGEOUT failing to drop a page because >>> of speculative references. We'll wait 1s and retry 10 times to >>> rule that unlikely case out as best as we can. >>> >>> On a machine without swap: >>> >>> $ ./droppable >>> TAP version 13 >>> 1..1 >>> ok 1 madvise(MADV_PAGEOUT) behavior >>> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0 >>> >>> Reported-by: Aishwarya TCV >>> Fixes: 9651fcedf7b9 ("mm: add MAP_DROPPABLE for designating always lazily freeable mappings") >>> Signed-off-by: David Hildenbrand (Arm) >>> --- >> >> I ran this test before and after applying the patch and recorded the >> execution time over 5 runs on an Orion O6 board. >> > > Thanks! > >> Before the patch, average execution time = 3.87 s > > Out of interest, how much memory did your machine have? > > I ran into this myself on a 200gig machine, and there was essentially no > progress ... > My board has about 15 GiB of RAM.