Add a new configfs attribute for enabling pipelining of zoned writes. If
that attribute has been set, retry zoned writes that are not aligned with
the write pointer. The test script below reports 244 K IOPS with no I/O
scheduler, 5.79 K IOPS with mq-deadline and pipelining disabled and 79.6 K
IOPS with mq-deadline and pipelining enabled. This shows that pipelining
results in about 14 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 pipelining <<<"$mode"
modprobe null_blk nr_devices=0
(
cd /sys/kernel/config/nullb
mkdir nullb0
cd nullb0
params=(
completion_nsec=100000
hw_queue_depth=64
irqmode=2 # NULL_IRQ_TIMER
max_sectors=$((4096/512))
memory_backed=1
pipeline_zoned_writes="${pipelining}"
size=1
submit_queues=1
zone_size=1
zoned=1
power=1
)
for p in "${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: Damien Le Moal <damien.lemoal@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
---
drivers/block/null_blk/main.c | 9 +++++++++
drivers/block/null_blk/null_blk.h | 3 +++
drivers/block/null_blk/zoned.c | 13 ++++++++++++-
3 files changed, 24 insertions(+), 1 deletion(-)
diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
index fd68e6f4637f..de9ed9a4ca10 100644
--- a/drivers/block/null_blk/main.c
+++ b/drivers/block/null_blk/main.c
@@ -408,6 +408,7 @@ 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(pipeline_zoned_writes, bool, NULL);
NULLB_DEVICE_ATTR(virt_boundary, bool, NULL);
static ssize_t nullb_device_power_show(struct config_item *item, char *page)
@@ -531,6 +532,7 @@ static struct configfs_attribute *nullb_device_attrs[] = {
&nullb_device_attr_zone_nr_conv,
&nullb_device_attr_zone_max_open,
&nullb_device_attr_zone_max_active,
+ &nullb_device_attr_pipeline_zoned_writes,
&nullb_device_attr_virt_boundary,
NULL,
};
@@ -1626,6 +1628,11 @@ static blk_status_t null_queue_rq(struct blk_mq_hw_ctx *hctx,
cmd->error = BLK_STS_OK;
cmd->nq = nq;
cmd->fake_timeout = should_timeout_request(rq);
+ if (!(rq->rq_flags & RQF_DONTPREP)) {
+ rq->rq_flags |= RQF_DONTPREP;
+ cmd->retries = 0;
+ cmd->max_attempts = rq->q->nr_requests;
+ }
blk_mq_start_request(rq);
@@ -2042,6 +2049,8 @@ static int null_add_dev(struct nullb_device *dev)
nullb->q->queuedata = nullb;
blk_queue_flag_set(QUEUE_FLAG_NONROT, nullb->q);
blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, nullb->q);
+ if (dev->pipeline_zoned_writes)
+ blk_queue_flag_set(QUEUE_FLAG_PIPELINE_ZONED_WRITES, nullb->q);
mutex_lock(&lock);
nullb->index = ida_simple_get(&nullb_indexes, 0, 0, GFP_KERNEL);
diff --git a/drivers/block/null_blk/null_blk.h b/drivers/block/null_blk/null_blk.h
index 8359b43842f2..bbe2cb17bdbd 100644
--- a/drivers/block/null_blk/null_blk.h
+++ b/drivers/block/null_blk/null_blk.h
@@ -23,6 +23,8 @@ struct nullb_cmd {
unsigned int tag;
blk_status_t error;
bool fake_timeout;
+ u16 retries;
+ u16 max_attempts;
struct nullb_queue *nq;
struct hrtimer timer;
};
@@ -112,6 +114,7 @@ struct nullb_device {
bool memory_backed; /* if data is stored in memory */
bool discard; /* if support discard */
bool zoned; /* if device is zoned */
+ bool pipeline_zoned_writes;
bool virt_boundary; /* virtual boundary on/off for the device */
};
diff --git a/drivers/block/null_blk/zoned.c b/drivers/block/null_blk/zoned.c
index 2fdd7b20c224..7138954dc01c 100644
--- a/drivers/block/null_blk/zoned.c
+++ b/drivers/block/null_blk/zoned.c
@@ -403,7 +403,18 @@ static blk_status_t null_zone_write(struct nullb_cmd *cmd, sector_t sector,
else
cmd->bio->bi_iter.bi_sector = sector;
} else if (sector != zone->wp) {
- ret = BLK_STS_IOERR;
+ /*
+ * In case of a misaligned write and if pipelining of zoned
+ * writes has been enabled, request the block layer to retry
+ * until the maximum number of attempts has been reached. If
+ * the maximum number of attempts has been reached, fail the
+ * misaligned write.
+ */
+ if (dev->pipeline_zoned_writes &&
+ ++cmd->retries < cmd->max_attempts)
+ ret = BLK_STS_DEV_RESOURCE;
+ else
+ ret = BLK_STS_IOERR;
goto unlock;
}
