Re: [PATCH v3 00/12] io-uring/btrfs: support async buffered writes

Filipe Manana
2022-09-13T09:48:07Z

On Mon, Sep 12, 2022 at 8:28 PM Stefan Roesch <shr@fb.com> wrote:
>
> This patch series adds support for async buffered writes when using both
> btrfs and io-uring. Currently io-uring only supports buffered writes (for btrfs)
> in the slow path, by processing them in the io workers. With this patch series
> it is now possible to support buffered writes in the fast path. To be able to use
> the fast path, the required pages must be in the page cache, the required locks
> in btrfs can be granted immediately and no additional blocks need to be read
> form disk.
>
> This patch series makes use of the changes that have been introduced by a
> previous patch series: "io-uring/xfs: support async buffered writes"
>
> Performance results:
>
> The new patch improves throughput by over two times (compared to the exiting
> behavior, where buffered writes are processed by an io-worker process) and also
> the latency is considerably reduced. Detailled results are part of the changelog
> of the first commit.

Not in the first, but in the last commit instead.

Looks fine to me now, thanks.

Reviewed-by: Filipe Manana <fdmanana@suse.com>

>
>
> BTRFS changes:
> -Add option for NOWAIT IOCB's to tell that searches do not wait on locks. This
> adds the nowait option to btrfs_path.
> -For NOWAIT buffered writes on PREALLOC or NOCOW extents tell can_nocow_extent()
> that we don't want to wait on any locks or metadata IO.
> -Support no_flush reservations for nowait buffered writes.
> -Add btrfs_try_lock_ordered_range() function.
> -Add nowait flag to btrfs_check_nocow_lock() to use it in write code path.
> -Add nowait parameter to prepare_pages() function.
> -Plumb nowait through the write code path.
> -Enable nowait buffered writes.
>
>
> Testing:
> This patch has been tested with xfstests, fsx, fio. xfstests shows no new
> diffs compared to running without the patch series.
>
>
> Changes:
>
> V3:
> - Updated changelog of "btrfs: implement a nowait option for tree searches"
> to say -EAGAIN.
> - Use bool return value in signature of btrfs_try_lock_ordered_range
> - Renamed variable tmp to can_nocow in btrfs_buffered_write
> - Fixed coding style in get_prepare_fgp_flags
> - Set pages[i] to NULL in error code path of lock_and_cleanup_extent_if_need()
> - Added const in definition of "bool nowait"
> - Removed unlikely from btrfs_buffered_write
> - Rephrased changelog for "btrfs: add assert to search functions" and used
> asserts instead of warnings
> - Explained why enocded writes are not supported in the changelog
> - Moved performance results to changelog of first commit
>
> V2:
> - Replace EWOULDBLOCK with EAGAIN. In Version 1 it was not used consistently
> - Export function balance_dirty_pages_ratelimited_flags()
> - Add asserts/warnings for search functions when nowait is set, but we don't
> expect that they are invoked with nowait set.
>
>
>
> Josef Bacik (5):
> btrfs: implement a nowait option for tree searches
> btrfs: make can_nocow_extent nowait compatible
> btrfs: add the ability to use NO_FLUSH for data reservations
> btrfs: add btrfs_try_lock_ordered_range
> btrfs: make btrfs_check_nocow_lock nowait compatible
>
> Stefan Roesch (7):
> mm: export balance_dirty_pages_ratelimited_flags()
> btrfs: make prepare_pages nowait compatible
> btrfs: make lock_and_cleanup_extent_if_need nowait compatible
> btrfs: plumb NOWAIT through the write path
> btrfs: make balance_dirty_pages nowait compatible
> btrfs: assert nowait mode is not used for some btree search functions
> btrfs: enable nowait async buffered writes
>
> fs/btrfs/block-group.c | 2 +-
> fs/btrfs/ctree.c | 43 ++++++++++++-
> fs/btrfs/ctree.h | 8 ++-
> fs/btrfs/delalloc-space.c | 13 +++-
> fs/btrfs/delalloc-space.h | 3 +-
> fs/btrfs/extent-tree.c | 5 ++
> fs/btrfs/file-item.c | 4 +-
> fs/btrfs/file.c | 124 ++++++++++++++++++++++++++++----------
> fs/btrfs/inode.c | 22 ++++---
> fs/btrfs/locking.c | 23 +++++++
> fs/btrfs/locking.h | 1 +
> fs/btrfs/ordered-data.c | 28 +++++++++
> fs/btrfs/ordered-data.h | 1 +
> fs/btrfs/relocation.c | 2 +-
> fs/btrfs/scrub.c | 4 +-
> fs/btrfs/space-info.c | 3 +-
> fs/btrfs/tree-log.c | 6 +-
> mm/page-writeback.c | 1 +
> 18 files changed, 234 insertions(+), 59 deletions(-)
>
>
> base-commit: 80e78fcce86de0288793a0ef0f6acf37656ee4cf
> --
> 2.30.2
>