Add a new configfs attribute for disabling zone write locking. The test
script below reports 250 K IOPS with no I/O scheduler, 6 K IOPS with
mq-deadline and write locking enabled and 123 K IOPS with mq-deadline
and write locking disabled. This shows that disabling write locking
results in about 20 times more IOPS for this particular test case.
#!/bin/bash
for mode in "none 0" "mq-deadline 0" "mq-deadline 1"; do
set +e
for d in /sys/kernel/config/nullb/*; do
[ -d "$d" ] && rmdir "$d"
done
modprobe -r null_blk
set -e
read -r iosched no_write_locking <<<"$mode"
modprobe null_blk nr_devices=0
(
cd /sys/kernel/config/nullb
mkdir nullb0
cd nullb0
params=(
completion_nsec=100000
hw_queue_depth=64
irqmode=2 # NULL_IRQ_TIMER
max_sectors=$((4096/512))
memory_backed=1
no_zone_write_lock="${no_write_locking}"
size=1
submit_queues=1
zone_size=1
zoned=1
power=1
)
for p in "${params[@]}"; do
echo "${p//*=}" > "${p//=*}"
done
)
udevadm settle
dev=/dev/nullb0
[ -b "${dev}" ]
params=(
--direct=1
--filename="${dev}"
--iodepth=64
--iodepth_batch=16
--ioengine=io_uring
--ioscheduler="${iosched}"
--gtod_reduce=1
--hipri=0
--name=nullb0
--runtime=30
--rw=write
--time_based=1
--zonemode=zbd
)
fio "${params[@]}"
done
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Damien Le Moal <damien.lemoal@xxxxxxxxxxxxxxxxxx>
Cc: Ming Lei <ming.lei@xxxxxxxxxx>
Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
---
drivers/block/null_blk/main.c | 2 ++
drivers/block/null_blk/null_blk.h | 1 +
drivers/block/null_blk/zoned.c | 3 +++
3 files changed, 6 insertions(+)
diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
index 864013019d6b..5c0578137f51 100644
--- a/drivers/block/null_blk/main.c
+++ b/drivers/block/null_blk/main.c
@@ -424,6 +424,7 @@ NULLB_DEVICE_ATTR(zone_capacity, ulong, NULL);
NULLB_DEVICE_ATTR(zone_nr_conv, uint, NULL);
NULLB_DEVICE_ATTR(zone_max_open, uint, NULL);
NULLB_DEVICE_ATTR(zone_max_active, uint, NULL);
+NULLB_DEVICE_ATTR(no_zone_write_lock, bool, NULL);
NULLB_DEVICE_ATTR(virt_boundary, bool, NULL);
NULLB_DEVICE_ATTR(no_sched, bool, NULL);
NULLB_DEVICE_ATTR(shared_tag_bitmap, bool, NULL);
@@ -569,6 +570,7 @@ static struct configfs_attribute *nullb_device_attrs[] = {
&nullb_device_attr_zone_max_active,
&nullb_device_attr_zone_readonly,
&nullb_device_attr_zone_offline,
+ &nullb_device_attr_no_zone_write_lock,
&nullb_device_attr_virt_boundary,
&nullb_device_attr_no_sched,
&nullb_device_attr_shared_tag_bitmap,
diff --git a/drivers/block/null_blk/null_blk.h b/drivers/block/null_blk/null_blk.h
index 929f659dd255..b521096bcc3f 100644
--- a/drivers/block/null_blk/null_blk.h
+++ b/drivers/block/null_blk/null_blk.h
@@ -117,6 +117,7 @@ struct nullb_device {
bool memory_backed; /* if data is stored in memory */
bool discard; /* if support discard */
bool zoned; /* if device is zoned */
+ bool no_zone_write_lock;
bool virt_boundary; /* virtual boundary on/off for the device */
bool no_sched; /* no IO scheduler for the device */
bool shared_tag_bitmap; /* use hostwide shared tags */
diff --git a/drivers/block/null_blk/zoned.c b/drivers/block/null_blk/zoned.c
index 55c5b48bc276..31c8364a63e9 100644
--- a/drivers/block/null_blk/zoned.c
+++ b/drivers/block/null_blk/zoned.c
@@ -96,6 +96,9 @@ int null_init_zoned_dev(struct nullb_device *dev, struct request_queue *q)
spin_lock_init(&dev->zone_res_lock);
+ if (dev->no_zone_write_lock)
+ blk_queue_flag_set(QUEUE_FLAG_NO_ZONE_WRITE_LOCK, q);
+
if (dev->zone_nr_conv >= dev->nr_zones) {
dev->zone_nr_conv = dev->nr_zones - 1;
pr_info("changed the number of conventional zones to %u",
