Hi, Some workloads benefit from NFSD avoiding the page cache, particularly those with a working set that is significantly larger than available system memory. This patchset introduces _optional_ support to configure the use of O_DIRECT or DONTCACHE for NFSD's READ and WRITE support. The NFSD default to use page cache is left unchanged. The performance win associated with using NFSD DIRECT was previously summarized here: https://lore.kernel.org/linux-nfs/aEslwqa9iMeZjjlV@xxxxxxxxxx/ This picture offers a nice summary of performance gains: https://original.art/NFSD_direct_vs_buffered_IO.jpg Similarly, NFS and LOCALIO in particular also benefit from avoiding the page cache for workloads that have a working set that is significantly larger than available system memory. Enter: NFS DIRECT, which makes it possible to always enable LOCALIO to use O_DIRECT even if the IO is not DIO-aligned. For this v5 I've combined the NFSD and NFSD patchsets because the NFS changes do depend on the the NFSD changes. In addition, I think it makes sense to review/test these changes together. I'm sharing these again now, soon after posting the NFSD and NFS updates, to hopefully make it clear where the code stands. Thanks to Chuck's feedback I have kept the patch "NFSD: issue READs using O_DIRECT even if IO is misaligned" (and will now finish NFSD's misaligned WRITE handling, splitting IO to misaligned head and/or tail and DIO-aligned middle, and will include in the next version of this patchset -- probably mid next week). New changes in this v5: - Combine NFSD DIRECT and NFS DIRECT patches into single patchset. - Fix a "nsfd" typo in a variable of the NFSD io_cache_read patch that was masked because the later " NFSD: issue READs using O_DIRECT even if IO is misaligned" patch fixed it. - Properly include the "NFSD: filecache: only get DIO alignment attrs if NFSD_IO_DIRECT enabled" in the patch series. - Optimize NFS DIRECT's misaligned READ and WRITE support to return early if IO irreparably misaligned or already DIO-aligned. Thanks, Mike Mike Snitzer (13): NFSD: filecache: add STATX_DIOALIGN and STATX_DIO_READ_ALIGN support NFSD: pass nfsd_file to nfsd_iter_read() NFSD: add io_cache_read controls to debugfs interface NFSD: add io_cache_write controls to debugfs interface NFSD: filecache: only get DIO alignment attrs if NFSD_IO_DIRECT enabled NFSD: issue READs using O_DIRECT even if IO is misaligned nfs/localio: avoid bouncing LOCALIO if nfs_client_is_local() nfs/localio: make trace_nfs_local_open_fh more useful nfs/localio: add nfsd_file_dio_alignment nfs/localio: refactor iocb initialization nfs/localio: fallback to NFSD for misaligned O_DIRECT READs nfs/direct: add misaligned READ handling nfs/direct: add misaligned WRITE handling fs/nfs/direct.c | 262 +++++++++++++++++++++++-- fs/nfs/flexfilelayout/flexfilelayout.c | 1 + fs/nfs/internal.h | 17 +- fs/nfs/localio.c | 231 ++++++++++++++-------- fs/nfs/nfstrace.h | 47 ++++- fs/nfs/pagelist.c | 22 ++- fs/nfsd/debugfs.c | 102 ++++++++++ fs/nfsd/filecache.c | 36 ++++ fs/nfsd/filecache.h | 4 + fs/nfsd/localio.c | 11 ++ fs/nfsd/nfs4xdr.c | 8 +- fs/nfsd/nfsd.h | 10 + fs/nfsd/nfsfh.c | 4 + fs/nfsd/trace.h | 37 ++++ fs/nfsd/vfs.c | 200 +++++++++++++++++-- fs/nfsd/vfs.h | 2 +- include/linux/nfs_page.h | 1 + include/linux/nfslocalio.h | 2 + include/linux/sunrpc/svc.h | 5 +- 19 files changed, 875 insertions(+), 127 deletions(-) -- 2.44.0
