Hi, > Commit ebb7fb1557b1 limited the length of ioend chains to 4096 entries > to improve worst-case latency. Unfortunately, this had the effect of > limiting the performance of: > > fio -name write-bandwidth -rw=write -bs=1024Ki -size=32Gi -runtime=30 \ > -iodepth 1 -ioengine sync -zero_buffers=1 -direct=0 -end_fsync=1 \ > -numjobs=4 -directory=/mnt/test > > The problem ends up being lock contention on the i_pages spinlock as we > clear the writeback bit on each folio (and propagate that up through > the tree). By using larger folios, we decrease the number of folios > to be processed by a factor of 256 for this benchmark, eliminating the > lock contention. > > It's also the right thing to do. This is a project that has been on > the back burner for years, it just hasn't been important enough to do > before now. > > I think it's probably best if this goes through the iomap tree since > the changes outside iomap are either to the page cache or they're > trivial. > > v3: > - Fix the handling of compound highmem pages in copy_page_from_iter_atomic() > - Rename fgp_t to fgf_t > - Clarify some wording in the documentation This v3 patches broken linux 6.4-rc7. fstests(btrfs/007 and more) will fail with the v3 patches . but it works well without the v3 patches. Best Regards Wang Yugui (wangyugui@xxxxxxxxxxxx) 2023/06/21 > v2: > - Fix misplaced semicolon > - Rename fgp_order to fgp_set_order > - Rename FGP_ORDER to FGP_GET_ORDER > - Add fgp_t > - Update the documentation for ->release_folio > - Fix iomap_invalidate_folio() > - Update iomap_release_folio() > > Matthew Wilcox (Oracle) (8): > iov_iter: Handle compound highmem pages in > copy_page_from_iter_atomic() > iomap: Remove large folio handling in iomap_invalidate_folio() > doc: Correct the description of ->release_folio > iomap: Remove unnecessary test from iomap_release_folio() > filemap: Add fgf_t typedef > filemap: Allow __filemap_get_folio to allocate large folios > iomap: Create large folios in the buffered write path > iomap: Copy larger chunks from userspace > > Documentation/filesystems/locking.rst | 15 ++++-- > fs/btrfs/file.c | 6 +-- > fs/f2fs/compress.c | 2 +- > fs/f2fs/f2fs.h | 2 +- > fs/gfs2/bmap.c | 2 +- > fs/iomap/buffered-io.c | 43 ++++++++-------- > include/linux/iomap.h | 2 +- > include/linux/pagemap.h | 71 ++++++++++++++++++++++----- > lib/iov_iter.c | 43 ++++++++++------ > mm/filemap.c | 61 ++++++++++++----------- > mm/folio-compat.c | 2 +- > mm/readahead.c | 13 ----- > 12 files changed, 159 insertions(+), 103 deletions(-) > > -- > 2.39.2
