Hi Lance, On Wed, 1 May 2024 12:26:57 +0800 Lance Yang <ioworker0@xxxxxxxxx> wrote: > Hi all, > > This series adds support for reclaiming PMD-mapped THP marked as lazyfree > without needing to first split the large folio via split_huge_pmd_address(). > > When the user no longer requires the pages, they would use madvise(MADV_FREE) > to mark the pages as lazy free. Subsequently, they typically would not re-write > to that memory again. > > During memory reclaim, if we detect that the large folio and its PMD are both > still marked as clean and there are no unexpected references(such as GUP), so we > can just discard the memory lazily, improving the efficiency of memory > reclamation in this case. > > Performance Testing > =================== > > On an Intel i5 CPU, reclaiming 1GiB of lazyfree THPs using > mem_cgroup_force_empty() results in the following runtimes in seconds > (shorter is better): > > -------------------------------------------- > | Old | New | Change | > -------------------------------------------- > | 0.683426 | 0.049197 | -92.80% | > -------------------------------------------- > > --- > > Changes since v3 [3] > ==================== > - mm/rmap: integrate PMD-mapped folio splitting into pagewalk loop > - Resolve compilation errors by handling the case where > CONFIG_PGTABLE_HAS_HUGE_LEAVES is undefined (thanks to SeongJae Park) I confirmed that the issue I reported before is disappeared with this version of the patchset. For the fix, Tested-by: SeongJae Park <sj@xxxxxxxxxx> Thanks, SJ [...]
