Remove test_generic_01.sh since block layer may reorder I/O, making the test prone to false positives. Apply the improvements to test_generic_02.sh instead, which supposes for covering ublk dispatch io order.
Rework test_generic_02 to verify that ublk dispatch doesn't reorder I/O by comparing request start order with completion order using bpftrace. The bpftrace script now: - Tracks each request's start sequence number in a map keyed by sector - On completion, verifies the request's start order matches expected completion order - Reports any out-of-order completions detected The test script: - Wait bpftrace BEGIN code block is run - Pins fio to CPU 0 for deterministic behavior - Uses block_io_start and block_rq_complete tracepoints - Checks bpftrace output for reordering errors Reported-and-tested-by: Alexander Atanasov <[email protected]> Signed-off-by: Ming Lei <[email protected]> --- tools/testing/selftests/ublk/Makefile | 3 +- .../testing/selftests/ublk/test_generic_01.sh | 47 ------------------- .../testing/selftests/ublk/test_generic_02.sh | 22 ++++++--- tools/testing/selftests/ublk/trace/seq_io.bt | 47 +++++++++++++++---- 4 files changed, 54 insertions(+), 65 deletions(-) delete mode 100755 tools/testing/selftests/ublk/test_generic_01.sh diff --git a/tools/testing/selftests/ublk/Makefile b/tools/testing/selftests/ublk/Makefile index a62a06e13006..8ac2d4a682a1 100644 --- a/tools/testing/selftests/ublk/Makefile +++ b/tools/testing/selftests/ublk/Makefile @@ -7,8 +7,7 @@ endif LDLIBS += -lpthread -lm -luring -TEST_PROGS := test_generic_01.sh -TEST_PROGS += test_generic_02.sh +TEST_PROGS := test_generic_02.sh TEST_PROGS += test_generic_03.sh TEST_PROGS += test_generic_06.sh TEST_PROGS += test_generic_07.sh diff --git a/tools/testing/selftests/ublk/test_generic_01.sh b/tools/testing/selftests/ublk/test_generic_01.sh deleted file mode 100755 index 26cf3c7ceeb5..000000000000 --- a/tools/testing/selftests/ublk/test_generic_01.sh +++ /dev/null @@ -1,47 +0,0 @@ -#!/bin/bash -# SPDX-License-Identifier: GPL-2.0 - -. "$(cd "$(dirname "$0")" && pwd)"/test_common.sh - -ERR_CODE=0 - -if ! _have_program bpftrace; then - exit "$UBLK_SKIP_CODE" -fi - -if ! _have_program fio; then - exit "$UBLK_SKIP_CODE" -fi - -_prep_test "null" "sequential io order" - -dev_id=$(_add_ublk_dev -t null) -_check_add_dev $TID $? - -dev_t=$(_get_disk_dev_t "$dev_id") -bpftrace trace/seq_io.bt "$dev_t" "W" 1 > "$UBLK_TMP" 2>&1 & -btrace_pid=$! -sleep 2 - -if ! kill -0 "$btrace_pid" > /dev/null 2>&1; then - _cleanup_test "null" - exit "$UBLK_SKIP_CODE" -fi - -# run fio over this ublk disk -fio --name=write_seq \ - --filename=/dev/ublkb"${dev_id}" \ - --ioengine=libaio --iodepth=16 \ - --rw=write \ - --size=512M \ - --direct=1 \ - --bs=4k > /dev/null 2>&1 -ERR_CODE=$? -kill "$btrace_pid" -wait -if grep -q "io_out_of_order" "$UBLK_TMP"; then - cat "$UBLK_TMP" - ERR_CODE=255 -fi -_cleanup_test "null" -_show_result $TID $ERR_CODE diff --git a/tools/testing/selftests/ublk/test_generic_02.sh b/tools/testing/selftests/ublk/test_generic_02.sh index 1d4b1d6e059c..46b657143fd6 100755 --- a/tools/testing/selftests/ublk/test_generic_02.sh +++ b/tools/testing/selftests/ublk/test_generic_02.sh @@ -13,7 +13,7 @@ if ! _have_program fio; then exit "$UBLK_SKIP_CODE" fi -_prep_test "null" "sequential io order for MQ" +_prep_test "null" "ublk dispatch won't reorder IO for MQ" dev_id=$(_add_ublk_dev -t null -q 2) _check_add_dev $TID $? @@ -21,15 +21,20 @@ _check_add_dev $TID $? dev_t=$(_get_disk_dev_t "$dev_id") bpftrace trace/seq_io.bt "$dev_t" "W" 1 > "$UBLK_TMP" 2>&1 & btrace_pid=$! -sleep 2 -if ! kill -0 "$btrace_pid" > /dev/null 2>&1; then +# Wait for bpftrace probes to be attached (BEGIN block prints BPFTRACE_READY) +for _ in $(seq 100); do + grep -q "BPFTRACE_READY" "$UBLK_TMP" 2>/dev/null && break + sleep 0.1 +done + +if ! kill -0 "$btrace_pid" 2>/dev/null; then _cleanup_test "null" exit "$UBLK_SKIP_CODE" fi -# run fio over this ublk disk -fio --name=write_seq \ +# run fio over this ublk disk (pinned to CPU 0) +taskset -c 0 fio --name=write_seq \ --filename=/dev/ublkb"${dev_id}" \ --ioengine=libaio --iodepth=16 \ --rw=write \ @@ -39,8 +44,11 @@ fio --name=write_seq \ ERR_CODE=$? kill "$btrace_pid" wait -if grep -q "io_out_of_order" "$UBLK_TMP"; then - cat "$UBLK_TMP" + +# Check for out-of-order completions detected by bpftrace +if grep -q "^out_of_order:" "$UBLK_TMP"; then + echo "I/O reordering detected:" + grep "^out_of_order:" "$UBLK_TMP" ERR_CODE=255 fi _cleanup_test "null" diff --git a/tools/testing/selftests/ublk/trace/seq_io.bt b/tools/testing/selftests/ublk/trace/seq_io.bt index b2f60a92b118..9d36ba35468f 100644 --- a/tools/testing/selftests/ublk/trace/seq_io.bt +++ b/tools/testing/selftests/ublk/trace/seq_io.bt @@ -2,23 +2,52 @@ $1: dev_t $2: RWBS $3: strlen($2) + + Track request order between block_io_start and block_rq_complete. + Sequence starts at 1 so 0 means "never seen". On first valid + completion, sync complete_seq to handle probe attachment races. + block_rq_complete listed first to reduce missed completion window. */ + BEGIN { - @last_rw[$1, str($2)] = (uint64)0; + @start_seq = (uint64)1; + @complete_seq = (uint64)0; + @out_of_order = (uint64)0; + @start_order[0] = (uint64)0; + delete(@start_order[0]); + printf("BPFTRACE_READY\n"); } + tracepoint:block:block_rq_complete +/(int64)args.dev == $1 && !strncmp(args.rwbs, str($2), $3)/ { - $dev = $1; - if ((int64)args.dev == $1 && !strncmp(args.rwbs, str($2), $3)) { - $last = @last_rw[$dev, str($2)]; - if ((uint64)args.sector != $last) { - printf("io_out_of_order: exp %llu actual %llu\n", - args.sector, $last); + $expected = @start_order[args.sector]; + if ($expected > 0) { + if (@complete_seq == 0) { + @complete_seq = $expected; + } + if ($expected != @complete_seq) { + printf("out_of_order: sector %llu started at seq %llu but completed at seq %llu\n", + args.sector, $expected, @complete_seq); + @out_of_order = @out_of_order + 1; } - @last_rw[$dev, str($2)] = (args.sector + args.nr_sector); + delete(@start_order[args.sector]); + @complete_seq = @complete_seq + 1; } } +tracepoint:block:block_io_start +/(int64)args.dev == $1 && !strncmp(args.rwbs, str($2), $3)/ +{ + @start_order[args.sector] = @start_seq; + @start_seq = @start_seq + 1; +} + END { - clear(@last_rw); + printf("total_start: %llu total_complete: %llu out_of_order: %llu\n", + @start_seq - 1, @complete_seq, @out_of_order); + clear(@start_order); + clear(@start_seq); + clear(@complete_seq); + clear(@out_of_order); } -- 2.47.0
