'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 <mpatalan@xxxxxxxxxx>
Cc: "Ewan D. Milne" <emilne@xxxxxxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
---
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 <ming.lei@xxxxxxxxxx>
+#
+# 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
