Commit 236918d3 authored by Uday Shankar's avatar Uday Shankar Committed by Jens Axboe
Browse files

selftests: ublk: add functional test for per io daemons 



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: default avatarUday Shankar <ushankar@purestorage.com>
Reviewed-by: default avatarMing Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250529-ublk_task_per_io-v8-7-e9d3b119336a@purestorage.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent abe54c16

tools/testing/selftests/ublk/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ TEST_PROGS += test_generic_08.sh 
TEST_PROGS += test_generic_09.sh

TEST_PROGS += test_generic_10.sh

TEST_PROGS += test_generic_11.sh

TEST_PROGS += test_generic_12.sh



TEST_PROGS += test_null_01.sh

TEST_PROGS += test_null_02.sh

tools/testing/selftests/ublk/test_generic_12.sh

0 → 100755
+55 −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="generic_12"

ERR_CODE=0



if ! _have_program bpftrace; then

	exit "$UBLK_SKIP_CODE"

fi



_prep_test "null" "do imbalanced load, it should be balanced over I/O threads"



NTHREADS=6

dev_id=$(_add_ublk_dev -t null -q 4 -d 16 --nthreads $NTHREADS --per_io_tasks)

_check_add_dev $TID $?



dev_t=$(_get_disk_dev_t "$dev_id")

bpftrace trace/count_ios_per_tid.bt "$dev_t" > "$UBLK_TMP" 2>&1 &

btrace_pid=$!

sleep 2



if ! kill -0 "$btrace_pid" > /dev/null 2>&1; then

	_cleanup_test "null"

	exit "$UBLK_SKIP_CODE"

fi



# do imbalanced I/O on the ublk device

# pin to cpu 0 to prevent migration/only target one queue

fio --name=write_seq \

    --filename=/dev/ublkb"${dev_id}" \

    --ioengine=libaio --iodepth=16 \

    --rw=write \

    --size=512M \

    --direct=1 \

    --bs=4k \

    --cpus_allowed=0 > /dev/null 2>&1

ERR_CODE=$?

kill "$btrace_pid"

wait



# check that every task handles some I/O, even though all I/O was issued

# from a single CPU. when ublk gets support for round-robin tag

# allocation, this check can be strengthened to assert that every thread

# handles the same number of I/Os

NR_THREADS_THAT_HANDLED_IO=$(grep -c '@' ${UBLK_TMP})

if [[ $NR_THREADS_THAT_HANDLED_IO -ne $NTHREADS ]]; then

        echo "only $NR_THREADS_THAT_HANDLED_IO handled I/O! expected $NTHREADS"

        cat "$UBLK_TMP"

        ERR_CODE=255

fi



_cleanup_test "null"

_show_result $TID $ERR_CODE

tools/testing/selftests/ublk/trace/count_ios_per_tid.bt

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+11 −0
Original line number Diff line number Diff line 
/*

 * Tabulates and prints I/O completions per thread for the given device

 *

 * $1: dev_t

*/

tracepoint:block:block_rq_complete

{

	if (args.dev == $1) {

		@[tid] = count();

	}

}