'nr_requests' can be a bit different for 'none' scheduler, and especially current blk-mq can only decrease this value for 'none.'
The patch of 'blk-mq: fix read/write 'nr_requests' in case of 'none' scheduler' has been sent out for fixing this issue. Cc: Marco Patalano <[email protected]> Cc: "Ewan D. Milne" <[email protected]> Signed-off-by: Ming Lei <[email protected]> --- tests/block/021 | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++ tests/block/021.out | 2 ++ 2 files changed, 53 insertions(+) create mode 100755 tests/block/021 create mode 100755 tests/block/021.out diff --git a/tests/block/021 b/tests/block/021 new file mode 100755 index 000000000000..b72d9bd8b41d --- /dev/null +++ b/tests/block/021 @@ -0,0 +1,51 @@ +#!/bin/bash +# +# Test blk-mq request allocation when hardware tags are limited. Regression +# test for commit e6fc46498784 ("blk-mq: avoid starving tag allocation after +# allocating process migrates"). +# +# Copyright (C) 2018 Ming Lei <[email protected]> +# +# This program is free software: you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation, either version 3 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see <http://www.gnu.org/licenses/>. + +DESCRIPTION="read/write nr_requests on null-blk with different scheduler" +QUICK=1 + +requires() { + _have_module null_blk +} + +test() { + echo "Running ${TEST_NAME}" + + modprobe -r null_blk + modprobe null_blk + + local scheds + # shellcheck disable=SC2207 + scheds=($(sed 's/[][]//g' /sys/block/nullb0/queue/scheduler)) + + for sched in "${scheds[@]}"; do + echo "Testing $sched" >> "$FULL" + echo "$sched" > /sys/block/nullb0/queue/scheduler + max_nr=`cat /sys/block/nullb0/queue/nr_requests` + for nr in `seq 4 $max_nr`; do + echo $nr > /sys/block/nullb0/queue/nr_requests + done + done + + modprobe -r null_blk + + echo "Test complete" +} diff --git a/tests/block/021.out b/tests/block/021.out new file mode 100755 index 000000000000..3a397c5c8ff5 --- /dev/null +++ b/tests/block/021.out @@ -0,0 +1,2 @@ +Running block/021 +Test complete -- 2.9.5
