Add a new test test_generic_12 which:
- sets up a ublk server with per_io_tasks and a different number of ublk
server threads and ublk_queues. This is possible now that these
objects are decoupled
- runs some I/O load from a single CPU
- verifies that all the ublk server threads handle some I/O
Before this changeset, this test fails, since I/O issued from one CPU is
always handled by the one ublk server thread. After this changeset, the
test passes.
In the future, the last check above may be strengthened to "verify that
all ublk server threads handle the same amount of I/O." However, this
requires some adjustments/bugfixes to tag allocation, so this work is
postponed to a followup.
Signed-off-by: Uday Shankar <ushankar@purestorage.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250529-ublk_task_per_io-v8-7-e9d3b119336a@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
block layer, ublk and io_uring might re-order IO in the past
- plug
- queue ublk io command via task work
Add one test for verifying if sequential WRITE IO is dispatched in order.
- null target is taken, so we can just observe io order from
`tracepoint:block:block_rq_complete` which represents the dispatch order
- WRITE IO is taken because READ may come from system-wide utility
Cc: Uday Shankar <ushankar@purestorage.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250322093218.431419-2-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
