| Message ID | 98cbe74e-91d8-9611-5ac0-b344b4365e79@kernel.dk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [GIT,PULL,v2] Improve iomap async dio performance | expand |
On 7/28/23 7:47 AM, Jens Axboe wrote: > Hi, > > Here's the pull request for improving async dio performance with > iomap. Contains a few generic cleanups as well, but the meat of it > is described in the tagged commit message below. > > Please pull for 6.6! > > > The following changes since commit ccff6d117d8dc8d8d86e8695a75e5f8b01e573bf: > > Merge tag 'perf-tools-fixes-for-v6.5-1-2023-07-18' of git://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools (2023-07-18 14:51:29 -0700) > > are available in the Git repository at: > > git://git.kernel.dk/linux.git tags/xfs-async-dio.6-2023-07-28 Darrick, I collected Dave's reviewed-by on all the patches. Same pull request as this one, only the commit meta data changed: git://git.kernel.dk/linux.git tags/xfs-async-dio.6-2023-08-01 Please pull!
Hi, Here's the pull request for improving async dio performance with iomap. Contains a few generic cleanups as well, but the meat of it is described in the tagged commit message below. Please pull for 6.6! The following changes since commit ccff6d117d8dc8d8d86e8695a75e5f8b01e573bf: Merge tag 'perf-tools-fixes-for-v6.5-1-2023-07-18' of git://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools (2023-07-18 14:51:29 -0700) are available in the Git repository at: git://git.kernel.dk/linux.git tags/xfs-async-dio.6-2023-07-28 for you to fetch changes up to 634aae6c33338308f92eb137b0ea4833457c2ce7: iomap: support IOCB_DIO_CALLER_COMP (2023-07-25 07:47:20 -0600) ---------------------------------------------------------------- Improve iomap/xfs async dio write performance iomap always punts async dio write completions to a workqueue, which has a cost in terms of efficiency (now you need an unrelated worker to process it) and latency (now you're bouncing a completion through an async worker, which is a classic slowdown scenario). io_uring handles IRQ completions via task_work, and for writes that don't need to do extra IO at completion time, we can safely complete them inline from that. This patchset adds IOCB_DIO_CALLER_COMP, which an IO issuer can set to inform the completion side that any extra work that needs doing for that completion can be punted to a safe task context. The iomap dio completion will happen in hard/soft irq context, and we need a saner context to process these completions. IOCB_DIO_CALLER_COMP is added, which can be set in a struct kiocb->ki_flags by the issuer. If the completion side of the iocb handling understands this flag, it can choose to set a kiocb->dio_complete() handler and just call ki_complete from IRQ context. The issuer must then ensure that this callback is processed from a task. io_uring punts IRQ completions to task_work already, so it's trivial wire it up to run more of the completion before posting a CQE. This is good for up to a 37% improvement in throughput/latency for low queue depth IO, patch 5 has the details. If we need to do real work at completion time, iomap will clear the IOMAP_DIO_CALLER_COMP flag. This work came about when Andres tested low queue depth dio writes for postgres and compared it to doing sync dio writes, showing that the async processing slows us down a lot. ---------------------------------------------------------------- Jens Axboe (8): iomap: cleanup up iomap_dio_bio_end_io() iomap: use an unsigned type for IOMAP_DIO_* defines iomap: treat a write through cache the same as FUA iomap: only set iocb->private for polled bio iomap: add IOMAP_DIO_INLINE_COMP fs: add IOCB flags related to passing back dio completions io_uring/rw: add write support for IOCB_DIO_CALLER_COMP iomap: support IOCB_DIO_CALLER_COMP fs/iomap/direct-io.c | 163 ++++++++++++++++++++++++++++++++++++++------------- include/linux/fs.h | 35 ++++++++++- io_uring/rw.c | 27 ++++++++- 3 files changed, 180 insertions(+), 45 deletions(-)