Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
selftests: ublk: handle UBLK_U_IO_COMMIT_IO_CMDS
Implement UBLK_U_IO_COMMIT_IO_CMDS to enable efficient batched
completion of I/O operations in the batch I/O framework.
This completes the batch I/O infrastructure by adding the commit
phase that notifies the kernel about completed I/O operations:
Key features:
- Batch multiple I/O completions into single UBLK_U_IO_COMMIT_IO_CMDS
- Dynamic commit buffer allocation and management per thread
- Automatic commit buffer preparation before processing events
- Commit buffer submission after processing completed I/Os
- Integration with existing completion workflows
Implementation details:
- ublk_batch_prep_commit() allocates and initializes commit buffers
- ublk_batch_complete_io() adds completed I/Os to current batch
- ublk_batch_commit_io_cmds() submits batched completions to kernel
- Modified ublk_process_io() to handle batch commit lifecycle
- Enhanced ublk_complete_io() to route to batch or legacy completion
The commit buffer stores completion information (tag, result, buffer
details) for multiple I/Os, then submits them all at once, significantly
reducing syscall overhead compared to individual I/O completions.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
authored by
Ming Lei
and committed by
Jens Axboe
dee7024f
d468930a
+122
-29
+70
-4
tools/testing/selftests/ublk/batch.c
+70
-4
tools/testing/selftests/ublk/batch.c
···
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cmd->elem_bytes = elem_bytes;
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cmd->nr_elem = nr_elem;
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-
user_data = build_user_data(buf_idx, _IOC_NR(op), 0, q_id, 0);
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user_data = build_user_data(buf_idx, _IOC_NR(op), nr_elem, q_id, 0);
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io_uring_sqe_set_data64(sqe, user_data);
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t->cmd_inflight += 1;
···
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if (op == _IOC_NR(UBLK_U_IO_PREP_IO_CMDS))
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ublk_assert(cqe->res == 0);
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-
else if (op == _IOC_NR(UBLK_U_IO_COMMIT_IO_CMDS))
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-
;//assert(cqe->res == t->commit_buf_size);
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-
else
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else if (op == _IOC_NR(UBLK_U_IO_COMMIT_IO_CMDS)) {
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int nr_elem = user_data_to_tgt_data(cqe->user_data);
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+
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ublk_assert(cqe->res == t->commit_buf_elem_size * nr_elem);
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} else
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ublk_assert(0);
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ublk_free_commit_buf(t, buf_idx);
···
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ublk_batch_compl_commit_cmd(t, cqe, op);
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return;
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}
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}
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+
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void ublk_batch_commit_io_cmds(struct ublk_thread *t)
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{
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struct io_uring_sqe *sqe;
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unsigned short buf_idx;
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unsigned short nr_elem = t->commit.done;
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+
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/* nothing to commit */
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if (!nr_elem) {
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ublk_free_commit_buf(t, t->commit.buf_idx);
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return;
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}
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ublk_io_alloc_sqes(t, &sqe, 1);
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buf_idx = t->commit.buf_idx;
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sqe->addr = (__u64)t->commit.elem;
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sqe->len = nr_elem * t->commit_buf_elem_size;
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+
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/* commit isn't per-queue command */
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ublk_init_batch_cmd(t, t->commit.q_id, sqe, UBLK_U_IO_COMMIT_IO_CMDS,
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t->commit_buf_elem_size, nr_elem, buf_idx);
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ublk_setup_commit_sqe(t, sqe, buf_idx);
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}
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+
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static void ublk_batch_init_commit(struct ublk_thread *t,
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unsigned short buf_idx)
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{
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/* so far only support 1:1 queue/thread mapping */
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t->commit.q_id = t->idx;
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t->commit.buf_idx = buf_idx;
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t->commit.elem = ublk_get_commit_buf(t, buf_idx);
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t->commit.done = 0;
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t->commit.count = t->commit_buf_size /
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t->commit_buf_elem_size;
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}
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void ublk_batch_prep_commit(struct ublk_thread *t)
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{
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unsigned short buf_idx = ublk_alloc_commit_buf(t);
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ublk_assert(buf_idx != UBLKS_T_COMMIT_BUF_INV_IDX);
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ublk_batch_init_commit(t, buf_idx);
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}
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+
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void ublk_batch_complete_io(struct ublk_thread *t, struct ublk_queue *q,
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unsigned tag, int res)
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{
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struct batch_commit_buf *cb = &t->commit;
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struct ublk_batch_elem *elem = (struct ublk_batch_elem *)(cb->elem +
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cb->done * t->commit_buf_elem_size);
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struct ublk_io *io = &q->ios[tag];
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ublk_assert(q->q_id == t->commit.q_id);
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elem->tag = tag;
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elem->buf_index = ublk_batch_io_buf_idx(t, q, tag);
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elem->result = res;
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if (!ublk_queue_no_buf(q))
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elem->buf_addr = (__u64) (uintptr_t) io->buf_addr;
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cb->done += 1;
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ublk_assert(cb->done <= cb->count);
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}
+7
-1
tools/testing/selftests/ublk/kublk.c
+7
-1
tools/testing/selftests/ublk/kublk.c
···
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return -ENODEV;
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ret = io_uring_submit_and_wait(&t->ring, 1);
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-
reapped = ublk_reap_events_uring(t);
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if (ublk_thread_batch_io(t)) {
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ublk_batch_prep_commit(t);
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reapped = ublk_reap_events_uring(t);
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ublk_batch_commit_io_cmds(t);
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} else {
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reapped = ublk_reap_events_uring(t);
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}
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ublk_dbg(UBLK_DBG_THREAD, "submit result %d, reapped %d stop %d idle %d\n",
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ret, reapped, (t->state & UBLKS_T_STOPPING),
+45
-24
tools/testing/selftests/ublk/kublk.h
+45
-24
tools/testing/selftests/ublk/kublk.h
···
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__u64 buf_addr;
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};
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struct batch_commit_buf {
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unsigned short q_id;
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unsigned short buf_idx;
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void *elem;
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unsigned short done;
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unsigned short count;
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};
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struct ublk_thread {
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struct ublk_dev *dev;
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unsigned idx;
···
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void *commit_buf;
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#define UBLKS_T_COMMIT_BUF_INV_IDX ((unsigned short)-1)
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struct allocator commit_buf_alloc;
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struct batch_commit_buf commit;
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struct io_uring ring;
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};
···
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return &q->ios[tag];
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}
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-
static inline int ublk_complete_io(struct ublk_thread *t, struct ublk_queue *q,
471
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unsigned tag, int res)
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{
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struct ublk_io *io = &q->ios[tag];
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-
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ublk_mark_io_done(io, res);
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-
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return ublk_queue_io_cmd(t, io);
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}
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static inline void ublk_queued_tgt_io(struct ublk_thread *t, struct ublk_queue *q,
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unsigned tag, int queued)
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{
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if (queued < 0)
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ublk_complete_io(t, q, tag, queued);
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else {
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struct ublk_io *io = ublk_get_io(q, tag);
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t->io_inflight += queued;
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io->tgt_ios = queued;
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io->result = 0;
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}
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}
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-
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static inline int ublk_completed_tgt_io(struct ublk_thread *t,
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struct ublk_queue *q, unsigned tag)
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{
···
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539
int ublk_batch_alloc_buf(struct ublk_thread *t);
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/* Free commit buffers and cleanup batch allocator */
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void ublk_batch_free_buf(struct ublk_thread *t);
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/* Prepare a new commit buffer for batching completed I/O operations */
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void ublk_batch_prep_commit(struct ublk_thread *t);
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/* Submit UBLK_U_IO_COMMIT_IO_CMDS with batched completed I/O operations */
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void ublk_batch_commit_io_cmds(struct ublk_thread *t);
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/* Add a completed I/O operation to the current batch commit buffer */
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void ublk_batch_complete_io(struct ublk_thread *t, struct ublk_queue *q,
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unsigned tag, int res);
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+
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static inline int ublk_complete_io(struct ublk_thread *t, struct ublk_queue *q,
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unsigned tag, int res)
553
+
{
554
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if (ublk_queue_batch_io(q)) {
555
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ublk_batch_complete_io(t, q, tag, res);
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return 0;
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} else {
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struct ublk_io *io = &q->ios[tag];
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ublk_mark_io_done(io, res);
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return ublk_queue_io_cmd(t, io);
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}
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}
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static inline void ublk_queued_tgt_io(struct ublk_thread *t, struct ublk_queue *q,
566
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unsigned tag, int queued)
567
+
{
568
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if (queued < 0)
569
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ublk_complete_io(t, q, tag, queued);
570
+
else {
571
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struct ublk_io *io = ublk_get_io(q, tag);
572
+
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t->io_inflight += queued;
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io->tgt_ios = queued;
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io->result = 0;
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}
577
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}
527
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579
extern const struct ublk_tgt_ops null_tgt_ops;
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extern const struct ublk_tgt_ops loop_tgt_ops;