Re: [PATCH V6 00/24] ublk: add UBLK_F_BATCH_IO

[Ming Lei <ming.lei@redhat.com>]

On Fri, Jan 16, 2026 at 10:18:33PM +0800, Ming Lei wrote:
> 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%
> 
> 
> Links: https://lore.kernel.org/linux-block/20251202121917.1412280-1-ming.lei@redhat.com/
> Links: https://lore.kernel.org/linux-block/20251121015851.3672073-1-ming.lei@redhat.com/
> Links: https://lore.kernel.org/linux-block/20251112093808.2134129-1-ming.lei@redhat.com/
> Links: https://lore.kernel.org/linux-block/20251023153234.2548062-1-ming.lei@redhat.com/
> Links: https://lore.kernel.org/linux-block/20250901100242.3231000-1-ming.lei@redhat.com/
> 
> 
> This patchset is based on for-7.0/block with the following two patches:
> 
> 	[PATCH v4] ublk: fix ublksrv pid handling for pid namespaces ( https://lore.kernel.org/linux-block/20260115025952.2321238-1-sconnor@purestorage.com/ )
> 
> 	[PATCH 0/3] selftests/ublk: three bug fixes ( https://lore.kernel.org/linux-block/20260113085805.233214-1-ming.lei@redhat.com/ ) 
> 
> 
> V6:
> 	- rebase on for-7.0/block
> 	- fix ublk_handle_non_batch_cmd() (Caleb Sander Mateos)
> 	- add `ublk: refactor ublk_queue_rq() and add ublk_batch_queue_rq()` (Caleb Sander Mateos)
> 	- add `ublk: fix batch I/O recovery -ENODEV error`
> 	- increase selftest timeout for running more things in some generic tests
> 	- fix kublk utility wrt. ->cmd_inflight accounting for BATCH_IO
> 	- pass all selftest after applying the io_uring cancel fix

Hi Jens,

Any chance to queue it for-7.0/block? And it is applied cleanly.



Thanks,
Ming