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From: Bart Van Assche <>
To: "" <>,
	"" <>,
	"" <>
Cc: "" <>,
	"" <>,
	Damien Le Moal <>
Subject: Re: [PATCH 0/2] null_blk: zone support
Date: Tue, 10 Jul 2018 16:47:32 +0000	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Tue, 2018-07-10 at 08:46 -0600, Jens Axboe wrote:
> On 7/9/18 6:05 PM, Bart Van Assche wrote:
> > On Mon, 2018-07-09 at 10:34 -0600, Jens Axboe wrote:
> > > In the spirit of making some progress on this, I just don't like how
> > > it's done. For example, it should not be necessary to adjust what
> > > comes out of the block generator, instead the block generator should
> > > be told to do what we need on zbc. This is a key concept. The workload
> > > should be defined as such that it works for zoned devices.
> > 
> > How would you like to see block generation work? I don't see an
> > alternative for random I/O other starting from the output of a random
> > generator and translating that output into something that is
> > appropriate for a zoned block device. Random reads must happen below
> > the zone pointer if fio is configured to read below the zone pointer.
> > Random writes must happen at the write pointer. The only way I see to
> > implement such an I/O pattern is to start from the output of a random
> > generator and to adjust the output of that random generator. However,
> > I don't have a strong opinion whether adjusting the output of a random
> > generator should happen by the caller of get_next_buflen() or inside
> > get_next_buflen(). Or is your concern perhaps that the current
> > approach interferes with fio job options like bs_unaligned?
> The main issue I have with that approach is that the core of fio is
> generating the IO patterns, and then you are just changing them as you
> see fit. This means that the workload definition and the resulting IO
> operations are no longer matched up, since they now also depend on what
> you are running on. If I take one workload and run it on a zoned drive,
> and then run it on a non-zoned drive, I can't compare the results at
> all. This is a showstopper.
> There should be no adjusting of the output, rather it should be possible
> to write zoned friendly job definitions. It should be possible to run
> the same job on a non-zoned drive, and vice versa, and the resulting IO
> patterns must be the same.
> Fio already has some notion of zones. Maybe that could be extended to
> hard zones, and some control of open zones, and patterns within those
> zones?

Hello Jens,

How about adding a job option that makes it possible to use the zoned
block device (ZBD) I/O pattern on non-ZBD devices, requiring that the
zone size is set explicitly for non-ZBD devices and maintaining a write
pointer not only when performing I/O to a ZBD device but also if a
ZBD-style I/O pattern is applied to a non-ZBD disk? This should allow to
apply exactly the same workload to a non-ZBD disk as to a ZBD disk.

What I derived from the fio source code is as follows (please correct me
if I got anything wrong):
* The purpose of the zonesize, zonerange and zoneskip job options is to
  limit the I/O range to a single zone with size "zonesize". The I/O
  pattern for zoned block devices is different: I/O happens in multiple
  zones simultaneously. The number of zones to which I/O happens is
  called the number of open zones.
* The purpose of the random_distribution=zoned{_abs} job option is to
  allow the user to skew a uniform random distribution. This is another
  workload pattern than the typical pattern for ZBD drives.



  reply	other threads:[~2018-07-10 16:47 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 [this message]
2018-07-10 18:45             ` Jens Axboe
2018-07-10 18:49               ` Bart Van Assche
2018-07-10 18:51                 ` Jens Axboe
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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