Messages in this thread |  | | From | Ming Lei <> | | Subject | [PATCH V4 00/27] ublk: add UBLK_F_BATCH_IO | | Date | Fri, 21 Nov 2025 09:58:22 +0800 |
| |
Hello,
This patchset adds UBLK_F_BATCH_IO feature for communicating between kernel and ublk server in batching way:
- Per-queue vs Per-I/O: Commands operate on queues rather than individual I/Os
- Batch processing: Multiple I/Os are handled in single operation
- Multishot commands: Use io_uring multishot for reducing submission overhead
- Flexible task assignment: Any task can handle any I/O (no per-I/O daemons)
- Better load balancing: Tasks can adjust their workload dynamically
- help for future optimizations: - blk-mq batch tags free - support io-poll - per-task batch for avoiding per-io lock - fetch command priority
- simplify command cancel process with per-queue lock
selftest are provided.
Performance test result(IOPS) on V3:
- page copy
tools/testing/selftests/ublk//kublk add -t null -q 16 [-b]
- zero copy(--auto_zc) tools/testing/selftests/ublk//kublk add -t null -q 16 --auto_zc [-b]
- IO test taskset -c 0-31 fio/t/io_uring -p0 -n $JOBS -r 30 /dev/ublkb0
1) 16 jobs IO - page copy: 37.77M vs. 42.40M(BATCH_IO), +12% - zero copy(--auto_zc): 42.83M vs. 44.43M(BATCH_IO), +3.7%
2) single job IO - page copy: 2.54M vs. 2.6M(BATCH_IO), +2.3% - zero copy(--auto_zc): 3.13M vs. 3.35M(BATCH_IO), +7%
V4: - fix handling in case of running out of mshot buffer, request has to be un-prepared for zero copy - don't expose unused tag to userspace - replace fixed buffer with plain user buffer for UBLK_U_IO_PREP_IO_CMDS and UBLK_U_IO_COMMIT_IO_CMDS - replace iov iterator with plain copy_from_user() for ublk_walk_cmd_buf(), code is simplified with performance improvement - don't touch sqe->len for UBLK_U_IO_PREP_IO_CMDS and UBLK_U_IO_COMMIT_IO_CMDS(Caleb Sander Mateos) - use READ_ONCE() for access sqe->addr (Caleb Sander Mateos) - all kinds of patch style fix(Caleb Sander Mateos) - inline __kfifo_alloc() (Caleb Sander Mateos)
V3: - rebase on for-6.19/block - use blk_mq_end_request_batch() to free requests in batch, only for page copy - fix one IO hang issue because of memory barrier order, comments on the memory barrier pairing - add NUMA ware kfifo_alloc_node() - fix one build warning reported by 0-DAY CI - selftests improvement & fix
V2: - ublk_config_io_buf() vs. __ublk_fetch() order - code style clean - use READ_ONCE() to cache sqe data because sqe copy becomes conditional recently - don't use sqe->len for UBLK_U_IO_PREP_IO_CMDS & UBLK_U_IO_COMMIT_IO_CMDS - fix one build warning - fix build_user_data() - run performance analysis, and find one bug in io_uring_cmd_buffer_select(), fix is posted already
Ming Lei (27): kfifo: add kfifo_alloc_node() helper for NUMA awareness ublk: add parameter `struct io_uring_cmd *` to ublk_prep_auto_buf_reg() ublk: add `union ublk_io_buf` with improved naming ublk: refactor auto buffer register in ublk_dispatch_req() ublk: pass const pointer to ublk_queue_is_zoned() ublk: add helper of __ublk_fetch() ublk: define ublk_ch_batch_io_fops for the coming feature F_BATCH_IO ublk: prepare for not tracking task context for command batch ublk: add new batch command UBLK_U_IO_PREP_IO_CMDS & UBLK_U_IO_COMMIT_IO_CMDS ublk: handle UBLK_U_IO_PREP_IO_CMDS ublk: handle UBLK_U_IO_COMMIT_IO_CMDS ublk: add io events fifo structure ublk: add batch I/O dispatch infrastructure ublk: add UBLK_U_IO_FETCH_IO_CMDS for batch I/O processing ublk: abort requests filled in event kfifo ublk: add new feature UBLK_F_BATCH_IO ublk: document feature UBLK_F_BATCH_IO ublk: implement batch request completion via blk_mq_end_request_batch() selftests: ublk: fix user_data truncation for tgt_data >= 256 selftests: ublk: replace assert() with ublk_assert() selftests: ublk: add ublk_io_buf_idx() for returning io buffer index selftests: ublk: add batch buffer management infrastructure selftests: ublk: handle UBLK_U_IO_PREP_IO_CMDS selftests: ublk: handle UBLK_U_IO_COMMIT_IO_CMDS selftests: ublk: handle UBLK_U_IO_FETCH_IO_CMDS selftests: ublk: add --batch/-b for enabling F_BATCH_IO selftests: ublk: support arbitrary threads/queues combination
Documentation/block/ublk.rst | 60 +- drivers/block/ublk_drv.c | 1312 +++++++++++++++-- include/linux/kfifo.h | 34 +- include/uapi/linux/ublk_cmd.h | 85 ++ lib/kfifo.c | 8 +- tools/testing/selftests/ublk/Makefile | 7 +- tools/testing/selftests/ublk/batch.c | 604 ++++++++ tools/testing/selftests/ublk/common.c | 2 +- tools/testing/selftests/ublk/file_backed.c | 11 +- tools/testing/selftests/ublk/kublk.c | 143 +- tools/testing/selftests/ublk/kublk.h | 195 ++- tools/testing/selftests/ublk/null.c | 18 +- tools/testing/selftests/ublk/stripe.c | 17 +- .../testing/selftests/ublk/test_generic_14.sh | 32 + .../testing/selftests/ublk/test_generic_15.sh | 30 + .../testing/selftests/ublk/test_generic_16.sh | 30 + .../testing/selftests/ublk/test_stress_06.sh | 45 + .../testing/selftests/ublk/test_stress_07.sh | 44 + tools/testing/selftests/ublk/utils.h | 64 + 19 files changed, 2563 insertions(+), 178 deletions(-) create mode 100644 tools/testing/selftests/ublk/batch.c create mode 100755 tools/testing/selftests/ublk/test_generic_14.sh create mode 100755 tools/testing/selftests/ublk/test_generic_15.sh create mode 100755 tools/testing/selftests/ublk/test_generic_16.sh create mode 100755 tools/testing/selftests/ublk/test_stress_06.sh create mode 100755 tools/testing/selftests/ublk/test_stress_07.sh
-- 2.47.0
|  |