From: Jens Axboe <axboe@kernel.dk>
To: Bart Van Assche <Bart.VanAssche@wdc.com>,
"mb@lightnvm.io" <mb@lightnvm.io>,
"loberman@redhat.com" <loberman@redhat.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
Damien Le Moal <Damien.LeMoal@wdc.com>
Subject: Re: [PATCH 0/2] null_blk: zone support
Date: Tue, 10 Jul 2018 12:51:55 -0600 [thread overview]
Message-ID: <be88923a-b960-0786-bd21-a4107cccd834@kernel.dk> (raw)
In-Reply-To: <ba99bc66928277b73cdbeb8579d739db0cf58639.camel@wdc.com>
On 7/10/18 12:49 PM, Bart Van Assche wrote:
> On Tue, 2018-07-10 at 12:45 -0600, Jens Axboe wrote:
>> The difference between the job file and the
>> workload run can be huge. Consider something really basic:
>>
>> [randwrites]
>> bs=4k
>> rw=randwrite
>>
>> which would be 100% random 4k writes. If I run this on a zoned device,
>> then that'd turn into 100% sequential writes.
>
> That's not correct. The ZBD code in the github pull request serializes writes
> per zone, not globally.
That's a totally minor detail. If all my random writes fall within a single
zone, then they'd be 100% sequential. For N open zones, you'd be 100%
sequential within the zone. The point is that the workload as defined and
the workload as run are two totally different things, and THAT is the
problem.
--
Jens Axboe
next prev parent reply other threads:[~2018-07-10 18:52 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-06 17:38 [PATCH 0/2] null_blk: zone support Matias Bjørling
2018-07-06 17:38 ` [PATCH 1/2] null_blk: move shared definitions to header file Matias Bjørling
2018-07-06 17:38 ` [PATCH 2/2] null_blk: add zone support Matias Bjørling
2018-07-06 17:45 ` [PATCH 0/2] null_blk: " Laurence Oberman
2018-07-09 7:54 ` Matias Bjørling
2018-07-09 16:34 ` Jens Axboe
2018-07-10 0:05 ` Bart Van Assche
2018-07-10 14:46 ` Jens Axboe
2018-07-10 16:47 ` Bart Van Assche
2018-07-10 18:45 ` Jens Axboe
2018-07-10 18:49 ` Bart Van Assche
2018-07-10 18:51 ` Jens Axboe [this message]
2018-08-09 20:51 ` Zoned block device support for fio (was: [PATCH 0/2] null_blk: zone support) Bart Van Assche
2018-08-09 21:03 ` Zoned block device support for fio Jens Axboe
2018-08-15 18:07 ` Bart Van Assche
2018-07-07 2:54 ` [PATCH 0/2] null_blk: zone support Jens Axboe
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