[PATCH blktests 0/3] Add QD=1 and gap zone tests

[PATCH blktests 0/3] Add QD=1 and gap zone tests

[Bart Van Assche]

Hi Omar,

This patch series adds two tests for queue depth one and two tests for SCSI
devices with gap zones. Please consider these patches for inclusion in the
official blktests repository.

Thanks,

Bart.

Bart Van Assche (3):
  Introduce the io_schedulers() function
  Add I/O scheduler tests for queue depth 1
  tests/scsi: Add tests for SCSI devices with gap zones

 common/iosched             | 12 +++++++
 common/multipath-over-rdma | 11 ------
 common/rc                  |  5 +++
 tests/block/005            |  4 +--
 tests/block/014            |  7 ++--
 tests/block/015            |  7 ++--
 tests/block/020            |  7 ++--
 tests/block/021            |  6 ++--
 tests/block/032            | 62 +++++++++++++++++++++++++++++++++
 tests/block/032.out        |  2 ++
 tests/nvmeof-mp/012        |  3 +-
 tests/scsi/008             | 63 ++++++++++++++++++++++++++++++++++
 tests/scsi/008.out         |  2 ++
 tests/scsi/009             | 56 ++++++++++++++++++++++++++++++
 tests/scsi/009.out         |  2 ++
 tests/scsi/010             | 70 ++++++++++++++++++++++++++++++++++++++
 tests/scsi/010.out         |  2 ++
 tests/srp/012              |  3 +-
 18 files changed, 290 insertions(+), 34 deletions(-)
 create mode 100644 common/iosched
 create mode 100755 tests/block/032
 create mode 100644 tests/block/032.out
 create mode 100755 tests/scsi/008
 create mode 100644 tests/scsi/008.out
 create mode 100755 tests/scsi/009
 create mode 100644 tests/scsi/009.out
 create mode 100644 tests/scsi/010
 create mode 100644 tests/scsi/010.out

[PATCH blktests 1/3] Introduce the io_schedulers() function

[Bart Van Assche]

The functionality for retrieving the I/O schedulers supported by a request
queue occurs multiple times. Hence introduce a function for retrieving the
supported I/O schedulers.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 common/iosched             | 12 ++++++++++++
 common/multipath-over-rdma | 11 -----------
 tests/block/005            |  4 ++--
 tests/block/014            |  7 ++-----
 tests/block/015            |  7 ++-----
 tests/block/020            |  7 ++-----
 tests/block/021            |  6 ++----
 tests/nvmeof-mp/012        |  3 ++-
 tests/srp/012              |  3 ++-
 9 files changed, 26 insertions(+), 34 deletions(-)
 create mode 100644 common/iosched

diff --git a/common/iosched b/common/iosched
new file mode 100644
index 000000000000..5dd46216afcb
--- /dev/null
+++ b/common/iosched
@@ -0,0 +1,12 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2022 Google LLC
+
+# Prints a space-separated list with the names of all I/O schedulers supported
+# by block device $1.
+io_schedulers() {
+	local path=/sys/class/block/$1/queue/scheduler
+
+	[ -e "${path}" ] || return 1
+	sed 's/[][]//g' "${path}"
+}
diff --git a/common/multipath-over-rdma b/common/multipath-over-rdma
index cef05ec92d29..75a5c832d6da 100644
--- a/common/multipath-over-rdma
+++ b/common/multipath-over-rdma
@@ -298,17 +298,6 @@ set_scheduler() {
 	fi
 }
 
-# Get block dev scheduler list
-get_scheduler_list() {
-	local b=$1 p
-	p=/sys/block/"$b"/queue/scheduler
-	if [ -e "$p" ]; then
-		sed 's/[][]//g' /sys/block/"$b"/queue/scheduler
-	else
-		return 1
-	fi
-}
-
 # Get a /dev/... path that points at dm device number $1. Set its I/O scheduler
 # to $2 and its timeout to $3. The shell script that includes this file must
 # define a function get_bdev_path() that translates device number $1 into a
diff --git a/tests/block/005 b/tests/block/005
index 77b9e2f57203..383c8f5b7d2b 100755
--- a/tests/block/005
+++ b/tests/block/005
@@ -5,6 +5,7 @@
 # Threads doing IO to a device, while we switch schedulers
 
 . tests/block/rc
+. common/iosched
 
 DESCRIPTION="switch schedulers while doing IO"
 TIMED=1
@@ -17,9 +18,8 @@ requires() {
 test_device() {
 	echo "Running ${TEST_NAME}"
 
-	local scheds
 	# shellcheck disable=SC2207
-	scheds=($(sed 's/[][]//g' "${TEST_DEV_SYSFS}/queue/scheduler"))
+	local scheds=($(io_schedulers "${TEST_DEV_SYSFS}"))
 
 	if _test_dev_is_rotational; then
 		size="32m"
diff --git a/tests/block/014 b/tests/block/014
index 04c34fa12b5c..78e90269389e 100755
--- a/tests/block/014
+++ b/tests/block/014
@@ -6,6 +6,7 @@
 
 . tests/block/rc
 . common/null_blk
+. common/iosched
 
 DESCRIPTION="run null-blk with blk-mq and timeout injection configured"
 
@@ -22,11 +23,7 @@ test() {
 		return 1
 	fi
 
-	local scheds
-	# shellcheck disable=SC2207
-	scheds=($(sed 's/[][]//g' /sys/block/nullb0/queue/scheduler))
-
-	for sched in "${scheds[@]}"; do
+	for sched in $(io_schedulers nullb0); do
 		echo "Testing $sched" >> "$FULL"
 		echo "$sched" > /sys/block/nullb0/queue/scheduler
 		# Do a bunch of I/Os which will timeout and then complete. The
diff --git a/tests/block/015 b/tests/block/015
index 79102a2bea54..5eb954b4906c 100755
--- a/tests/block/015
+++ b/tests/block/015
@@ -7,6 +7,7 @@
 
 . tests/block/rc
 . common/null_blk
+. common/iosched
 
 DESCRIPTION="run null-blk on different schedulers with requeue injection configured"
 QUICK=1
@@ -24,11 +25,7 @@ test() {
 		return 1
 	fi
 
-	local scheds
-	# shellcheck disable=SC2207
-	scheds=($(sed 's/[][]//g' /sys/block/nullb0/queue/scheduler))
-
-	for sched in "${scheds[@]}"; do
+	for sched in $(io_schedulers nullb0); do
 		echo "Testing $sched" >> "$FULL"
 		echo "$sched" > /sys/block/nullb0/queue/scheduler
 		dd if=/dev/nullb0 of=/dev/null bs=4K count=$((512 * 1024)) \
diff --git a/tests/block/020 b/tests/block/020
index b4887a26ff0a..0301129e1c1d 100755
--- a/tests/block/020
+++ b/tests/block/020
@@ -8,6 +8,7 @@
 
 . tests/block/rc
 . common/null_blk
+. common/iosched
 
 DESCRIPTION="run null-blk on different schedulers with only one hardware tag"
 QUICK=1
@@ -25,16 +26,12 @@ test() {
 		return 1
 	fi
 
-	local scheds
-	# shellcheck disable=SC2207
-	scheds=($(sed 's/[][]//g' /sys/block/nullb0/queue/scheduler))
-
 	local max_iodepth=$(($(cat /proc/sys/fs/aio-max-nr) / $(nproc)))
 	local iodepth=1024
 	if (( iodepth > max_iodepth )); then
 		iodepth=$max_iodepth
 	fi
-	for sched in "${scheds[@]}"; do
+	for sched in $(io_schedulers nullb0); do
 		echo "Testing $sched" >> "$FULL"
 		echo "$sched" > /sys/block/nullb0/queue/scheduler
 		_fio_perf --bs=4k --ioengine=libaio --iodepth=$iodepth \
diff --git a/tests/block/021 b/tests/block/021
index a1bbf45a3bc9..7b562de0f99c 100755
--- a/tests/block/021
+++ b/tests/block/021
@@ -8,6 +8,7 @@
 
 . tests/block/rc
 . common/null_blk
+. common/iosched
 
 DESCRIPTION="read/write nr_requests on null-blk with different schedulers"
 QUICK=1
@@ -26,11 +27,8 @@ test() {
 
 	local max_nr
 	local nr
-	local scheds
-	# shellcheck disable=SC2207
-	scheds=($(sed 's/[][]//g' /sys/block/nullb0/queue/scheduler))
 
-	for sched in "${scheds[@]}"; do
+	for sched in $(io_schedulers nullb0); do
 		echo "Testing $sched" >> "$FULL"
 		echo "$sched" > /sys/block/nullb0/queue/scheduler
 		max_nr="$(cat /sys/block/nullb0/queue/nr_requests)"
diff --git a/tests/nvmeof-mp/012 b/tests/nvmeof-mp/012
index 8b2e918773e5..0b56dfb46d1e 100755
--- a/tests/nvmeof-mp/012
+++ b/tests/nvmeof-mp/012
@@ -3,6 +3,7 @@
 # Copyright (c) 2018 Western Digital Corporation or its affiliates
 
 . tests/nvmeof-mp/rc
+. common/iosched
 
 DESCRIPTION="dm-mpath on top of multiple I/O schedulers"
 QUICK=1
@@ -18,7 +19,7 @@ test_io_schedulers() {
 		use_blk_mq ${mq} || return $?
 		dev=$(get_bdev 0) || return $?
 		dm=$(basename "$(readlink -f "${dev}")") || return $?
-		scheds="$(get_scheduler_list "$dm")" || return $?
+		scheds="$(io_schedulers "$dm")" || return $?
 		for sched in $scheds; do
 			set_scheduler "$dm" "$sched" \
 				      >>"$FULL" 2>&1 || continue
diff --git a/tests/srp/012 b/tests/srp/012
index 1a2fc6d2dc2f..7c72288b773b 100755
--- a/tests/srp/012
+++ b/tests/srp/012
@@ -3,6 +3,7 @@
 # Copyright (c) 2018 Western Digital Corporation or its affiliates
 
 . tests/srp/rc
+. common/iosched
 
 DESCRIPTION="dm-mpath on top of multiple I/O schedulers"
 QUICK=1
@@ -22,7 +23,7 @@ test_io_schedulers() {
 		use_blk_mq ${mq} ${mq} || return $?
 		dev=$(get_bdev 0) || return $?
 		dm=$(basename "$(readlink -f "${dev}")") || return $?
-		scheds="$(get_scheduler_list "$dm")" || return $?
+		scheds="$(io_schedulers "$dm")" || return $?
 		for sched in $scheds; do
 			set_scheduler "$dm" "$sched" \
 				      >>"$FULL" 2>&1 || continue

[PATCH blktests 2/3] Add I/O scheduler tests for queue depth 1

[Bart Van Assche]

Some block devices, e.g. USB sticks, only support queue depth 1. The
QD=1 code paths do not get tested routinely. Hence add tests for the
QD=1 use case.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 common/rc           |  5 ++++
 tests/block/032     | 62 ++++++++++++++++++++++++++++++++++++++++++++
 tests/block/032.out |  2 ++
 tests/scsi/008      | 63 +++++++++++++++++++++++++++++++++++++++++++++
 tests/scsi/008.out  |  2 ++
 5 files changed, 134 insertions(+)
 create mode 100755 tests/block/032
 create mode 100644 tests/block/032.out
 create mode 100755 tests/scsi/008
 create mode 100644 tests/scsi/008.out

diff --git a/common/rc b/common/rc
index 0528ce808256..2377e223aea7 100644
--- a/common/rc
+++ b/common/rc
@@ -321,6 +321,11 @@ _uptime_s() {
 	awk '{ print int($1) }' /proc/uptime
 }
 
+# System uptime in centiseconds.
+_uptime_cs() {
+	sed 's/\.//;s/ .*//' /proc/uptime
+}
+
 # Arguments: module to unload ($1) and retry count ($2).
 unload_module() {
 	local i m=$1 rc=${2:-1}
diff --git a/tests/block/032 b/tests/block/032
new file mode 100755
index 000000000000..8b4d30282988
--- /dev/null
+++ b/tests/block/032
@@ -0,0 +1,62 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2022 Google LLC
+
+. tests/block/rc
+. common/null_blk
+. common/iosched
+
+DESCRIPTION="test I/O scheduler performance of null_blk with queue_depth 1"
+QUICK=1
+
+requires() {
+	_have_null_blk
+}
+
+# Measure the time required to perform I/O on dev $1 with I/O scheduler $2.
+sched_time() {
+	local dev=$1 sched=$2
+	echo "$sched" > "/sys/block/$dev/queue/scheduler"
+	local start
+	start=$(_uptime_cs)
+	dd if="/dev/$dev" of=/dev/null bs=4K count=$((512 * 1024)) \
+	   iflag=direct status=none &
+	dd of="/dev/$dev" if=/dev/zero bs=4K count=$((512 * 1024)) \
+	   oflag=direct status=none &
+	wait
+	echo $(($(_uptime_cs) - start))
+}
+
+test() {
+	echo "Running ${TEST_NAME}"
+
+	local params=(
+		hw_queue_depth=1
+		queue_mode=2
+	)
+	_init_null_blk "${params[@]}" || return 1
+
+	local dev=nullb0 fail status
+
+	none_time_cs=$(sched_time "$dev" none)
+	for sched in $(io_schedulers "$dev"); do
+		[ "$sched" = none ] && continue
+		time_cs=$(sched_time "$dev" "$sched")
+		if [ "$time_cs" -lt $(("$none_time_cs" * 110 / 100)) ]; then
+			status=pass
+		else
+			status=fail
+			fail=true
+		fi
+		TEST_RUN[$sched]="$time_cs vs $none_time_cs: $status"
+	done
+
+	_exit_null_blk
+
+	if [ -z "$fail" ]; then
+		echo "Test complete"
+	else
+		echo "Test failed"
+		return 1
+	fi
+}
diff --git a/tests/block/032.out b/tests/block/032.out
new file mode 100644
index 000000000000..3604e9e1e751
--- /dev/null
+++ b/tests/block/032.out
@@ -0,0 +1,2 @@
+Running block/032
+Test complete
diff --git a/tests/scsi/008 b/tests/scsi/008
new file mode 100755
index 000000000000..dec304fd29a2
--- /dev/null
+++ b/tests/scsi/008
@@ -0,0 +1,63 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2022 Google LLC
+
+. tests/scsi/rc
+. common/iosched
+. common/scsi_debug
+
+DESCRIPTION="test I/O scheduler performance of scsi_debug with queue_depth 1"
+QUICK=1
+
+requires() {
+	_have_scsi_debug
+}
+
+# Measure the time required to perform I/O on dev $1 with I/O scheduler $2.
+sched_time() {
+	local dev=$1 sched=$2
+	echo "$sched" > "/sys/block/$dev/queue/scheduler"
+	local start
+	start=$(_uptime_cs)
+	dd if="/dev/$dev" of=/dev/null bs=4K count=$((512 * 1024)) \
+	   iflag=direct status=none &
+	dd of="/dev/$dev" if=/dev/zero bs=4K count=$((512 * 1024)) \
+	   oflag=direct status=none &
+	wait
+	echo $(($(_uptime_cs) - start))
+}
+
+test() {
+	echo "Running ${TEST_NAME}"
+
+	local params=(
+		delay=0
+		dev_size_mb=2048
+		host_max_queue=1
+	)
+	_init_scsi_debug "${params[@]}" || return 1
+
+	local dev="${SCSI_DEBUG_DEVICES[0]}" fail
+
+	none_time_cs=$(sched_time "$dev" none)
+	for sched in $(io_schedulers "$dev"); do
+		[ "$sched" = none ] && continue
+		time_cs=$(sched_time "$dev" "$sched")
+		if [ "$time_cs" -lt $(("$none_time_cs" * 110 / 100)) ]; then
+			status=pass
+		else
+			status=fail
+			fail=true
+		fi
+		TEST_RUN[$sched]="$time_cs vs $none_time_cs: $status"
+	done
+
+	_exit_scsi_debug
+
+	if [ -z "$fail" ]; then
+		echo "Test complete"
+	else
+		echo "Test failed"
+		return 1
+	fi
+}
diff --git a/tests/scsi/008.out b/tests/scsi/008.out
new file mode 100644
index 000000000000..135bd5ae4b2d
--- /dev/null
+++ b/tests/scsi/008.out
@@ -0,0 +1,2 @@
+Running scsi/008
+Test complete

[PATCH blktests 3/3] tests/scsi: Add tests for SCSI devices with gap zones

[Bart Van Assche]

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 tests/scsi/009     | 56 +++++++++++++++++++++++++++++++++++++
 tests/scsi/009.out |  2 ++
 tests/scsi/010     | 70 ++++++++++++++++++++++++++++++++++++++++++++++
 tests/scsi/010.out |  2 ++
 4 files changed, 130 insertions(+)
 create mode 100755 tests/scsi/009
 create mode 100644 tests/scsi/009.out
 create mode 100644 tests/scsi/010
 create mode 100644 tests/scsi/010.out

diff --git a/tests/scsi/009 b/tests/scsi/009
new file mode 100755
index 000000000000..38f771f14e02
--- /dev/null
+++ b/tests/scsi/009
@@ -0,0 +1,56 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2022 Google LLC
+
+. tests/scsi/rc
+. common/scsi_debug
+
+DESCRIPTION="test gap zone support with BTRFS"
+QUICK=1
+
+requires() {
+	_have_fio &&
+	_have_module_param scsi_debug zone_cap_mb &&
+	_have_program mkfs.btrfs
+}
+
+test() {
+	echo "Running ${TEST_NAME}"
+
+	local params=(
+		delay=0
+		dev_size_mb=1024
+		sector_size=4096
+		zbc=host-managed
+		zone_cap_mb=3
+		zone_nr_conv=16
+		zone_size_mb=4
+	)
+	_init_scsi_debug "${params[@]}" || return 1
+
+	local dev="/dev/${SCSI_DEBUG_DEVICES[0]}" fail
+
+	mkfs.btrfs "${dev}" >>"${FULL}" 2>&1 &&
+	local mount_dir="$TMPDIR/mnt" &&
+	mkdir -p "${mount_dir}" &&
+	mount -t btrfs "${dev}" "${mount_dir}" &&
+	local fio_args=(
+		--size=1M
+		--directory="${mount_dir}"
+		--time_based
+		--runtime=10
+	) &&
+	_run_fio_verify_io "${fio_args[@]}" >>"${FULL}" 2>&1 ||
+	fail=true
+
+	umount "${mount_dir}" >>"${FULL}" 2>&1
+
+	_exit_scsi_debug
+
+	if [ -z "$fail" ]; then
+		echo "Test complete"
+	else
+		echo "Test failed"
+		return 1
+	fi
+}
diff --git a/tests/scsi/009.out b/tests/scsi/009.out
new file mode 100644
index 000000000000..f6db2a371d9e
--- /dev/null
+++ b/tests/scsi/009.out
@@ -0,0 +1,2 @@
+Running scsi/009
+Test complete
diff --git a/tests/scsi/010 b/tests/scsi/010
new file mode 100644
index 000000000000..4fdc6f82e732
--- /dev/null
+++ b/tests/scsi/010
@@ -0,0 +1,70 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2022 Google LLC
+
+. tests/scsi/rc
+. common/null_blk
+. common/scsi_debug
+
+DESCRIPTION="test gap zone support with F2FS"
+QUICK=1
+
+requires() {
+	_have_fio &&
+	_have_modules null_blk &&
+	_have_module_param scsi_debug zone_cap_mb &&
+	_have_program mkfs.f2fs
+}
+
+test() {
+	echo "Running ${TEST_NAME}"
+
+	local mount_dir="$TMPDIR/mnt"
+
+	local null_blk_params=(
+		blocksize=4096
+		completion_nsec=0
+		memory_backed=1
+		size=1024 # MB
+		submit_queues=1
+		power=1
+	)
+	_init_null_blk nr_devices=0 queue_mode=2 &&
+	_configure_null_blk nullb0 "${null_blk_params[@]}" || return $?
+	local cdev=/dev/nullb0
+
+	local scsi_debug_params=(
+		delay=0
+		dev_size_mb=1024
+		sector_size=4096
+		zbc=host-managed
+		zone_cap_mb=3
+		zone_nr_conv=0
+		zone_size_mb=4
+	)
+	_init_scsi_debug "${scsi_debug_params[@]}" &&
+	local zdev="/dev/${SCSI_DEBUG_DEVICES[0]}" fail &&
+	ls -ld "${cdev}" "${zdev}" >>"${FULL}" &&
+	mkfs.f2fs -m "${cdev}" -c "${zdev}" >>"${FULL}" 2>&1 &&
+	mkdir -p "${mount_dir}" &&
+	mount -t f2fs "${cdev}" "${mount_dir}" &&
+	local fio_args=(
+		--size=1M
+		--directory="${mount_dir}"
+		--time_based
+		--runtime=10
+	) &&
+	_run_fio_verify_io "${fio_args[@]}" >>"${FULL}" 2>&1 ||
+	fail=true
+
+	umount "${mount_dir}" >>"${FULL}" 2>&1
+	_exit_scsi_debug
+	_exit_null_blk
+
+	if [ -z "$fail" ]; then
+		echo "Test complete"
+	else
+		echo "Test failed"
+		return 1
+	fi
+}
diff --git a/tests/scsi/010.out b/tests/scsi/010.out
new file mode 100644
index 000000000000..6581d5eb2c5a
--- /dev/null
+++ b/tests/scsi/010.out
@@ -0,0 +1,2 @@
+Running scsi/010
+Test complete

Re: [PATCH blktests 3/3] tests/scsi: Add tests for SCSI devices with gap zones

[Shinichiro Kawasaki]

On Apr 27, 2022 / 14:31, Bart Van Assche wrote:
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>

Hi Bart, the desciption is missing, so I expect you will add it later.

I think the added test cases fit better with zbd group rather than scsi group
since the gap between zone capacity and zone size exists for non-scsi ZNS
devices also. What do you think?

-- 
Best Regards,
Shin'ichiro Kawasaki

Re: [PATCH blktests 3/3] tests/scsi: Add tests for SCSI devices with gap zones

[Bart Van Assche]

On 4/27/22 17:39, Shinichiro Kawasaki wrote:
> On Apr 27, 2022 / 14:31, Bart Van Assche wrote:
>> Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> 
> Hi Bart, the desciption is missing, so I expect you will add it later.
> 
> I think the added test cases fit better with zbd group rather than scsi group
> since the gap between zone capacity and zone size exists for non-scsi ZNS
> devices also. What do you think?

Hi Shinichiro,

Thanks for having taken a look. I will add a description and move these 
tests to the zbd group.

Bart.

Re: [PATCH blktests 1/3] Introduce the io_schedulers() function

[Shinichiro Kawasaki]

On Apr 27, 2022 / 14:31, Bart Van Assche wrote:
> The functionality for retrieving the I/O schedulers supported by a request
> queue occurs multiple times. Hence introduce a function for retrieving the
> supported I/O schedulers.
> 
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>

[...]

> diff --git a/tests/block/005 b/tests/block/005
> index 77b9e2f57203..383c8f5b7d2b 100755
> --- a/tests/block/005
> +++ b/tests/block/005
> @@ -5,6 +5,7 @@
>  # Threads doing IO to a device, while we switch schedulers
>  
>  . tests/block/rc
> +. common/iosched
>  
>  DESCRIPTION="switch schedulers while doing IO"
>  TIMED=1
> @@ -17,9 +18,8 @@ requires() {
>  test_device() {
>  	echo "Running ${TEST_NAME}"
>  
> -	local scheds
>  	# shellcheck disable=SC2207
> -	scheds=($(sed 's/[][]//g' "${TEST_DEV_SYSFS}/queue/scheduler"))
> +	local scheds=($(io_schedulers "${TEST_DEV_SYSFS}"))

I ran block/005 with this patch and observed it fails without failure message.
To fix it, the line above should be:
        local scheds=($(io_schedulers "$(basename "${TEST_DEV}")"))

-- 
Best Regards,
Shin'ichiro Kawasaki

Re: [PATCH blktests 2/3] Add I/O scheduler tests for queue depth 1

[Shinichiro Kawasaki]

On Apr 27, 2022 / 14:31, Bart Van Assche wrote:
> Some block devices, e.g. USB sticks, only support queue depth 1. The
> QD=1 code paths do not get tested routinely. Hence add tests for the
> QD=1 use case.
> 
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>

I tried this new test case on recent Fedora kernel 5.16.20-200.fc35.x86_64 and
Intel Core i9 machine, then observed failure:

$ sudo ./check block/032
block/032 (test I/O scheduler performance of null_blk with queue_depth 1) [failed]
    bfq          679 vs 243: fail  ...  679 vs 252: fail
    kyber        542 vs 243: fail  ...  551 vs 252: fail
    mq-deadline  577 vs 243: fail  ...  572 vs 252: fail
    runtime      20.514s           ...  20.660s
    --- tests/block/032.out     2022-04-27 22:02:46.602861565 -0700
    +++ /home/shin/kts/kernel-test-suite/src/blktests/results/nodev/block/032.out.bad2022-04-27 23:18:48.470170788 -0700
    @@ -1,2 +1,2 @@
     Running block/032
    -Test complete
    +Test failed

I tried v5.18-rcX kernel versions and machines (QEMU or VMware) but the test
case failed on all of the trials. Do I miss anything to make the test case pass?

-- 
Best Regards,
Shin'ichiro Kawasaki

Re: [PATCH blktests 2/3] Add I/O scheduler tests for queue depth 1

[Bart Van Assche]

On 4/27/22 23:27, Shinichiro Kawasaki wrote:
> On Apr 27, 2022 / 14:31, Bart Van Assche wrote:
>> Some block devices, e.g. USB sticks, only support queue depth 1. The
>> QD=1 code paths do not get tested routinely. Hence add tests for the
>> QD=1 use case.
>>
>> Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> 
> I tried this new test case on recent Fedora kernel 5.16.20-200.fc35.x86_64 and
> Intel Core i9 machine, then observed failure:
> 
> $ sudo ./check block/032
> block/032 (test I/O scheduler performance of null_blk with queue_depth 1) [failed]
>      bfq          679 vs 243: fail  ...  679 vs 252: fail
>      kyber        542 vs 243: fail  ...  551 vs 252: fail
>      mq-deadline  577 vs 243: fail  ...  572 vs 252: fail
>      runtime      20.514s           ...  20.660s
>      --- tests/block/032.out     2022-04-27 22:02:46.602861565 -0700
>      +++ /home/shin/kts/kernel-test-suite/src/blktests/results/nodev/block/032.out.bad2022-04-27 23:18:48.470170788 -0700
>      @@ -1,2 +1,2 @@
>       Running block/032
>      -Test complete
>      +Test failed
> 
> I tried v5.18-rcX kernel versions and machines (QEMU or VMware) but the test
> case failed on all of the trials. Do I miss anything to make the test case pass?

Hi Shinichiro,

The two tests added by this patch pass when using the legacy block layer 
(kernel v4.19) but not when using blk-mq. I see this as a (performance) 
bug in blk-mq. With blk-mq an excessive number of queue runs is 
triggered for QD=1 if multiple processes try to submit I/O concurrently.

Thanks,

Bart.

Re: [PATCH blktests 1/3] Introduce the io_schedulers() function

[Bart Van Assche]

On 4/27/22 20:50, Shinichiro Kawasaki wrote:
> On Apr 27, 2022 / 14:31, Bart Van Assche wrote:
>> -	local scheds
>>   	# shellcheck disable=SC2207
>> -	scheds=($(sed 's/[][]//g' "${TEST_DEV_SYSFS}/queue/scheduler"))
>> +	local scheds=($(io_schedulers "${TEST_DEV_SYSFS}"))
> 
> I ran block/005 with this patch and observed it fails without failure message.
> To fix it, the line above should be:
>          local scheds=($(io_schedulers "$(basename "${TEST_DEV}")"))
> 

This is something I should have noticed myself. I will fix this.

Thanks,

Bart.

Re: [PATCH blktests 2/3] Add I/O scheduler tests for queue depth 1

[Shinichiro Kawasaki]

On Apr 28, 2022 / 12:52, Bart Van Assche wrote:
> On 4/27/22 23:27, Shinichiro Kawasaki wrote:
> > On Apr 27, 2022 / 14:31, Bart Van Assche wrote:
> > > Some block devices, e.g. USB sticks, only support queue depth 1. The
> > > QD=1 code paths do not get tested routinely. Hence add tests for the
> > > QD=1 use case.
> > > 
> > > Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> > 
> > I tried this new test case on recent Fedora kernel 5.16.20-200.fc35.x86_64 and
> > Intel Core i9 machine, then observed failure:
> > 
> > $ sudo ./check block/032
> > block/032 (test I/O scheduler performance of null_blk with queue_depth 1) [failed]
> >      bfq          679 vs 243: fail  ...  679 vs 252: fail
> >      kyber        542 vs 243: fail  ...  551 vs 252: fail
> >      mq-deadline  577 vs 243: fail  ...  572 vs 252: fail
> >      runtime      20.514s           ...  20.660s
> >      --- tests/block/032.out     2022-04-27 22:02:46.602861565 -0700
> >      +++ /home/shin/kts/kernel-test-suite/src/blktests/results/nodev/block/032.out.bad2022-04-27 23:18:48.470170788 -0700
> >      @@ -1,2 +1,2 @@
> >       Running block/032
> >      -Test complete
> >      +Test failed
> > 
> > I tried v5.18-rcX kernel versions and machines (QEMU or VMware) but the test
> > case failed on all of the trials. Do I miss anything to make the test case pass?
> 
> Hi Shinichiro,
> 
> The two tests added by this patch pass when using the legacy block layer
> (kernel v4.19) but not when using blk-mq. I see this as a (performance) bug
> in blk-mq. With blk-mq an excessive number of queue runs is triggered for
> QD=1 if multiple processes try to submit I/O concurrently.

Thanks. So we need the fix in blk-mq before we merge this test case to blktests.

-- 
Best Regards,
Shin'ichiro Kawasaki