Re: [PATCH 13/16] null_blk: allow non power of 2 zoned devices

Hannes Reinecke
2022-05-04T17:48:42Z

On 4/27/22 09:02, Pankaj Raghav wrote:
> 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>
> Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
> ---
> drivers/block/null_blk/main.c | 4 ++--
> drivers/block/null_blk/zoned.c | 14 +++++++-------
> 2 files changed, 9 insertions(+), 9 deletions(-)
>
Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
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