Convert the power of 2 based calculation with zone size to be generic in
null_zone_no with optimization for power of 2 based zone sizes.
The nr_zones calculation in null_init_zoned_dev has been replaced with a
division without special handling for power of 2 based zone sizes as
this function is called only during the initialization and will not
invoked in the hot path.
Performance Measurement:
Device:
zone size = 128M, blocksize=4k
FIO cmd:
fio --name=zbc --filename=/dev/nullb0 --direct=1 --zonemode=zbd --size=23G
--io_size=<iosize> --ioengine=io_uring --iodepth=<iod> --rw=<mode> --bs=4k
--loops=4
The following results are an average of 4 runs on AMD Ryzen 5 5600X with
32GB of RAM:
Sequential Write:
x-----------------x---------------------------------x---------------------------------x
| IOdepth | 8 | 16 |
x-----------------x---------------------------------x---------------------------------x
| | KIOPS |BW(MiB/s) | Lat(usec) | KIOPS |BW(MiB/s) | Lat(usec) |
x-----------------x---------------------------------x---------------------------------x
| Without patch | 578 | 2257 | 12.80 | 576 | 2248 | 25.78 |
x-----------------x---------------------------------x---------------------------------x
| With patch | 581 | 2268 | 12.74 | 576 | 2248 | 25.85 |
x-----------------x---------------------------------x---------------------------------x
Sequential read:
x-----------------x---------------------------------x---------------------------------x
| IOdepth | 8 | 16 |
x-----------------x---------------------------------x---------------------------------x
| | KIOPS |BW(MiB/s) | Lat(usec) | KIOPS |BW(MiB/s) | Lat(usec) |
x-----------------x---------------------------------x---------------------------------x
| Without patch | 667 | 2605 | 11.79 | 675 | 2637 | 23.49 |
x-----------------x---------------------------------x---------------------------------x
| With patch | 667 | 2605 | 11.79 | 675 | 2638 | 23.48 |
x-----------------x---------------------------------x---------------------------------x
Random read:
x-----------------x---------------------------------x---------------------------------x
| IOdepth | 8 | 16 |
x-----------------x---------------------------------x---------------------------------x
| | KIOPS |BW(MiB/s) | Lat(usec) | KIOPS |BW(MiB/s) | Lat(usec) |
x-----------------x---------------------------------x---------------------------------x
| Without patch | 522 | 2038 | 15.05 | 514 | 2006 | 30.87 |
x-----------------x---------------------------------x---------------------------------x
| With patch | 522 | 2039 | 15.04 | 523 | 2042 | 30.33 |
x-----------------x---------------------------------x---------------------------------x
Minor variations are noticed in Sequential write with io depth 8 and
in random read with io depth 16. But overall no noticeable differences
were noticed
Reviewed-by: Luis Chamberlain <mcgrof@xxxxxxxxxx>
Reviewed by: Adam Manzanares <a.manzanares@xxxxxxxxxxx>
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
Signed-off-by: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
---
drivers/block/null_blk/main.c | 5 ++---
drivers/block/null_blk/null_blk.h | 6 ++++++
drivers/block/null_blk/zoned.c | 18 +++++++++++-------
3 files changed, 19 insertions(+), 10 deletions(-)
diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
index c451c477978f..f1e0605dee94 100644
--- a/drivers/block/null_blk/main.c
+++ b/drivers/block/null_blk/main.c
@@ -1976,9 +1976,8 @@ static int null_validate_conf(struct nullb_device *dev)
if (dev->queue_mode == NULL_Q_BIO)
dev->mbps = 0;
- if (dev->zoned &&
- (!dev->zone_size || !is_power_of_2(dev->zone_size))) {
- pr_err("zone_size must be power-of-two\n");
+ if (dev->zoned && !dev->zone_size) {
+ pr_err("Invalid zero zone size\n");
return -EINVAL;
}
diff --git a/drivers/block/null_blk/null_blk.h b/drivers/block/null_blk/null_blk.h
index 94ff68052b1e..ece6dded9508 100644
--- a/drivers/block/null_blk/null_blk.h
+++ b/drivers/block/null_blk/null_blk.h
@@ -83,6 +83,12 @@ struct nullb_device {
unsigned int imp_close_zone_no;
struct nullb_zone *zones;
sector_t zone_size_sects;
+ /*
+ * zone_size_sects_shift is only useful when the zone size is
+ * power of 2. This variable is set to zero when zone size is non
+ * power of 2.
+ */
+ unsigned int zone_size_sects_shift;
bool need_zone_res_mgmt;
spinlock_t zone_res_lock;
diff --git a/drivers/block/null_blk/zoned.c b/drivers/block/null_blk/zoned.c
index 55a69e48ef8b..015f6823706c 100644
--- a/drivers/block/null_blk/zoned.c
+++ b/drivers/block/null_blk/zoned.c
@@ -16,7 +16,10 @@ static inline sector_t mb_to_sects(unsigned long mb)
static inline unsigned int null_zone_no(struct nullb_device *dev, sector_t sect)
{
- return sect >> ilog2(dev->zone_size_sects);
+ if (dev->zone_size_sects_shift)
+ return sect >> dev->zone_size_sects_shift;
+
+ return div64_u64(sect, dev->zone_size_sects);
}
static inline void null_lock_zone_res(struct nullb_device *dev)
@@ -65,10 +68,6 @@ int null_init_zoned_dev(struct nullb_device *dev, struct request_queue *q)
sector_t sector = 0;
unsigned int i;
- if (!is_power_of_2(dev->zone_size)) {
- pr_err("zone_size must be power-of-two\n");
- return -EINVAL;
- }
if (dev->zone_size > dev->size) {
pr_err("Zone size larger than device capacity\n");
return -EINVAL;
@@ -86,9 +85,14 @@ int null_init_zoned_dev(struct nullb_device *dev, struct request_queue *q)
zone_capacity_sects = mb_to_sects(dev->zone_capacity);
dev_capacity_sects = mb_to_sects(dev->size);
dev->zone_size_sects = mb_to_sects(dev->zone_size);
- dev->nr_zones = round_up(dev_capacity_sects, dev->zone_size_sects)
- >> ilog2(dev->zone_size_sects);
+ if (is_power_of_2(dev->zone_size_sects))
+ dev->zone_size_sects_shift = ilog2(dev->zone_size_sects);
+ else
+ dev->zone_size_sects_shift = 0;
+
+ dev->nr_zones = DIV_ROUND_UP_SECTOR_T(dev_capacity_sects,
+ dev->zone_size_sects);
dev->zones = kvmalloc_array(dev->nr_zones, sizeof(struct nullb_zone),
GFP_KERNEL | __GFP_ZERO);
if (!dev->zones)
--
2.25.1
