Commit 8cb9b971 authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

selftests: ublk: enable zero copy for null target 



Enable zero copy for null target so that we can evaluate performance
from zero copy or not.

Also this should be the simplest ublk zero copy implementation, which
can be served as zc example.

Add test for covering 'add -t null -z'.

Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250322093218.431419-7-ming.lei@redhat.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 8842b72a

tools/testing/selftests/ublk/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ LDLIBS += -lpthread -lm -luring 
TEST_PROGS := test_generic_01.sh



TEST_PROGS += test_null_01.sh

TEST_PROGS += test_null_02.sh

TEST_PROGS += test_loop_01.sh

TEST_PROGS += test_loop_02.sh

TEST_PROGS += test_loop_03.sh

tools/testing/selftests/ublk/kublk.h

+5 −0
Original line number Diff line number Diff line
@@ -198,6 +198,11 @@ static inline unsigned int user_data_to_tgt_data(__u64 user_data) 
	return (user_data >> 24) & 0xffff;

}



static inline unsigned short ublk_cmd_op_nr(unsigned int op)

{

	return _IOC_NR(op);

}



static inline void ublk_err(const char *fmt, ...)

{

	va_list ap;

tools/testing/selftests/ublk/null.c

+69 −1
Original line number Diff line number Diff line
@@ -2,6 +2,14 @@ 


#include "kublk.h"



#ifndef IORING_NOP_INJECT_RESULT

#define IORING_NOP_INJECT_RESULT        (1U << 0)

#endif



#ifndef IORING_NOP_FIXED_BUFFER

#define IORING_NOP_FIXED_BUFFER         (1U << 3)

#endif



static int ublk_null_tgt_init(const struct dev_ctx *ctx, struct ublk_dev *dev)

{

	const struct ublksrv_ctrl_dev_info *info = &dev->dev_info;
@@ -20,19 +28,79 @@ static int ublk_null_tgt_init(const struct dev_ctx *ctx, struct ublk_dev *dev) 
		},

	};



	if (info->flags & UBLK_F_SUPPORT_ZERO_COPY)

		dev->tgt.sq_depth = dev->tgt.cq_depth = 2 * info->queue_depth;

	return 0;

}



static int null_queue_zc_io(struct ublk_queue *q, int tag)

{

	const struct ublksrv_io_desc *iod = ublk_get_iod(q, tag);

	unsigned ublk_op = ublksrv_get_op(iod);

	struct io_uring_sqe *sqe[3];



	ublk_queue_alloc_sqes(q, sqe, 3);



	io_uring_prep_buf_register(sqe[0], 0, tag, q->q_id, tag);

	sqe[0]->user_data = build_user_data(tag,

			ublk_cmd_op_nr(sqe[0]->cmd_op), 0, 1);

	sqe[0]->flags |= IOSQE_CQE_SKIP_SUCCESS | IOSQE_IO_HARDLINK;



	io_uring_prep_nop(sqe[1]);

	sqe[1]->buf_index = tag;

	sqe[1]->flags |= IOSQE_FIXED_FILE | IOSQE_IO_HARDLINK;

	sqe[1]->rw_flags = IORING_NOP_FIXED_BUFFER | IORING_NOP_INJECT_RESULT;

	sqe[1]->len = iod->nr_sectors << 9; 	/* injected result */

	sqe[1]->user_data = build_user_data(tag, ublk_op, 0, 1);



	io_uring_prep_buf_unregister(sqe[2], 0, tag, q->q_id, tag);

	sqe[2]->user_data = build_user_data(tag, ublk_cmd_op_nr(sqe[2]->cmd_op), 0, 1);



	// buf register is marked as IOSQE_CQE_SKIP_SUCCESS

	return 2;

}



static void ublk_null_io_done(struct ublk_queue *q, int tag,

		const struct io_uring_cqe *cqe)

{

	unsigned op = user_data_to_op(cqe->user_data);

	struct ublk_io *io = ublk_get_io(q, tag);



	if (cqe->res < 0 || op != ublk_cmd_op_nr(UBLK_U_IO_UNREGISTER_IO_BUF)) {

		if (!io->result)

			io->result = cqe->res;

		if (cqe->res < 0)

			ublk_err("%s: io failed op %x user_data %lx\n",

					__func__, op, cqe->user_data);

	}



	/* buffer register op is IOSQE_CQE_SKIP_SUCCESS */

	if (op == ublk_cmd_op_nr(UBLK_U_IO_REGISTER_IO_BUF))

		io->tgt_ios += 1;



	if (ublk_completed_tgt_io(q, tag))

		ublk_complete_io(q, tag, io->result);

}



static int ublk_null_queue_io(struct ublk_queue *q, int tag)

{

	const struct ublksrv_io_desc *iod = ublk_get_iod(q, tag);

	int zc = ublk_queue_use_zc(q);

	int queued;



	if (!zc) {

		ublk_complete_io(q, tag, iod->nr_sectors << 9);

		return 0;

	}



	queued = null_queue_zc_io(q, tag);

	ublk_queued_tgt_io(q, tag, queued);

	return 0;

}



const struct ublk_tgt_ops null_tgt_ops = {

	.name = "null",

	.init_tgt = ublk_null_tgt_init,

	.queue_io = ublk_null_queue_io,

	.tgt_io_done = ublk_null_io_done,

};

tools/testing/selftests/ublk/test_null_02.sh

0 → 100755
+20 −0
Original line number Diff line number Diff line 
#!/bin/bash

# SPDX-License-Identifier: GPL-2.0



. "$(cd "$(dirname "$0")" && pwd)"/test_common.sh



TID="null_02"

ERR_CODE=0



_prep_test "null" "basic IO test with zero copy"



dev_id=$(_add_ublk_dev -t null -z)

_check_add_dev $TID $?



# run fio over the two disks

fio --name=job1 --filename=/dev/ublkb"${dev_id}" --ioengine=libaio --rw=readwrite --iodepth=32 --size=256M > /dev/null 2>&1

ERR_CODE=$?



_cleanup_test "null"



_show_result $TID $ERR_CODE