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 <[email protected]> >> Fixes: 9651fcedf7b9 ("mm: add MAP_DROPPABLE for designating always lazily >> freeable mappings") >> Signed-off-by: David Hildenbrand (Arm) <[email protected]> >> --- > > 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 ... -- Cheers, David
