Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <681ca5e1-d318-765a-af91-6d5d377ae958@suse.de>
Date:   Wed, 4 May 2022 10:10:25 -0700
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Thunderbird/91.4.0
Subject: Re: [PATCH 13/16] null_blk: allow non power of 2 zoned devices
Content-Language: en-US
References: <20220427160255.300418-1-p.raghav@samsung.com>
 <CGME20220427160310eucas1p28cd3c5ff4fb7a04bc77c4c0b9d96bb74@eucas1p2.samsung.com>
 <20220427160255.300418-14-p.raghav@samsung.com>
From:   Hannes Reinecke <hare@suse.de>
To:     undisclosed-recipients:;
In-Reply-To: <20220427160255.300418-14-p.raghav@samsung.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
Precedence: bulk

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
hare@suse.de                              +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer