On Fri, Jun 05, 2026 at 10:14:15AM -0600, Nico Pache wrote: >Add three new mTHP statistics to track collapse failures for different >orders when encountering swap PTEs, excessive none PTEs, and shared PTEs: > >- collapse_exceed_swap_pte: Increment when mTHP collapse fails due to > encountering a swap PTE. > >- collapse_exceed_none_pte: Counts when mTHP collapse fails due to > exceeding the none PTE threshold for the given order > >- collapse_exceed_shared_pte: Counts when mTHP collapse fails due to > encountering a shared PTE. > >These statistics complement the existing THP_SCAN_EXCEED_* events by >providing per-order granularity for mTHP collapse attempts. The stats are >exposed via sysfs under >`/sys/kernel/mm/transparent_hugepage/hugepages-*/stats/` for each >supported hugepage size. > >As we currently do not support collapsing mTHPs that contain a swap or >shared entry, those statistics keep track of how often we are >encountering failed mTHP collapses due to these restrictions. > >We will add support for mTHP collapse for anonymous pages next; lets also >track when this happens at the PMD level within the per-mTHP stats. > >Reviewed-by: Lorenzo Stoakes <[email protected]> >Acked-by: David Hildenbrand (Arm) <[email protected]> >Signed-off-by: Nico Pache <[email protected]> >---
Reviewed-by: Lance Yang <[email protected]>
