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null_blk: allow non power of 2 zoned devices
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@kernel.org>
Reviewed by: Adam Manzanares <a.manzanares@samsung.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
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Panky-codes authored and intel-lab-lkp committed May 23, 2022
1 parent aec2f3d commit 3d3c81d
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Showing 2 changed files with 9 additions and 10 deletions.
5 changes: 2 additions & 3 deletions drivers/block/null_blk/main.c
Expand Up @@ -1935,9 +1935,8 @@ 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;
}

Expand Down
14 changes: 7 additions & 7 deletions drivers/block/null_blk/zoned.c
Expand Up @@ -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 (is_power_of_2(dev->zone_size_sects))
return sect >> ilog2(dev->zone_size_sects);

return div64_u64(sect, dev->zone_size_sects);
}

static inline void null_lock_zone_res(struct nullb_device *dev)
Expand Down Expand Up @@ -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;
Expand All @@ -86,8 +85,9 @@ 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);
dev->nr_zones =
div64_u64(roundup(dev_capacity_sects, dev->zone_size_sects),
dev->zone_size_sects);

dev->zones = kvmalloc_array(dev->nr_zones, sizeof(struct nullb_zone),
GFP_KERNEL | __GFP_ZERO);
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