From: Keith Busch <kbusch@kernel.org>
To: Heiner Litz <hlitz@ucsc.edu>
Cc: "Jens Axboe" <axboe@kernel.dk>,
"Niklas Cassel" <Niklas.Cassel@wdc.com>,
"Damien Le Moal" <Damien.LeMoal@wdc.com>,
"Ajay Joshi" <Ajay.Joshi@wdc.com>,
"Sagi Grimberg" <sagi@grimberg.me>,
"Keith Busch" <Keith.Busch@wdc.com>,
"Dmitry Fomichev" <Dmitry.Fomichev@wdc.com>,
"Aravind Ramesh" <Aravind.Ramesh@wdc.com>,
"Javier González" <javier@javigon.com>,
"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"Hans Holmberg" <Hans.Holmberg@wdc.com>,
"Matias Bjørling" <mb@lightnvm.io>,
"Judy Brock" <judy.brock@samsung.com>,
"Christoph Hellwig" <hch@lst.de>,
"Matias Bjorling" <Matias.Bjorling@wdc.com>
Subject: Re: [PATCH 5/5] nvme: support for zoned namespaces
Date: Fri, 19 Jun 2020 11:22:12 -0700 [thread overview]
Message-ID: <20200619182212.GA1284056@dhcp-10-100-145-180.wdl.wdc.com> (raw)
In-Reply-To: <CAJbgVnWru+wRRsJ4KB2DiVPRNfMV39uYNSCi2Y=6d+_GOQO8iw@mail.gmail.com>
On Fri, Jun 19, 2020 at 11:17:02AM -0700, Heiner Litz wrote:
> > On Fri, Jun 19, 2020 at 11:08:26AM -0700, Heiner Litz wrote:
> > > Hi Matias,
> > > no, I am rather saying that the Linux kernel has a deficit or at least
> > > is not a good fit for ZNS because it cannot enforce in-order delivery.
> >
> > FYI, the nvme protocol can't even enforce in-order delivery, so calling
> > out linux for this is a moot point.
>
> How does it work in SPDK then? I had understood that SPDK supported
> QD>1 for ZNS devices.
> I am not saying that Linux is the only problem. The fact remains that
> out of order delivery is not a good fit for an interface that requires
> sequential writes.
The nvme protocol is absoltely clear that multiple commands outstanding
simultaneosly can be executed in any order. This is further made
difficult if you're dispatching these commands across multiple queues.
If SPDK is dispatching multiple commands and expecting them to execute
in order, then they're doing it wrong.
Further, you're not even guranteed the first write in a sequence will be
successful. If you've already dispatched a subsequent write, and the
first one fails, the second one may also fail when it's not at the wrong
write pointer.
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next prev parent reply other threads:[~2020-06-19 18:22 UTC|newest]
Thread overview: 96+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-15 23:34 [PATCH 0/5] nvme support for zoned namespace command set Keith Busch
2020-06-15 23:34 ` [PATCH 1/5] block: add capacity field to zone descriptors Keith Busch
2020-06-15 23:49 ` Chaitanya Kulkarni
2020-06-16 10:28 ` Javier González
2020-06-16 13:47 ` Daniel Wagner
2020-06-16 13:54 ` Johannes Thumshirn
2020-06-16 15:41 ` Martin K. Petersen
2020-06-15 23:34 ` [PATCH 2/5] null_blk: introduce zone capacity for zoned device Keith Busch
2020-06-15 23:46 ` Chaitanya Kulkarni
2020-06-16 14:18 ` Daniel Wagner
2020-06-16 15:48 ` Martin K. Petersen
2020-06-15 23:34 ` [PATCH 3/5] nvme: implement I/O Command Sets Command Set support Keith Busch
2020-06-16 10:33 ` Javier González
2020-06-16 17:14 ` Niklas Cassel
2020-06-16 15:58 ` Martin K. Petersen
2020-06-16 17:01 ` Keith Busch
2020-06-17 9:50 ` Niklas Cassel
2020-06-16 17:06 ` Niklas Cassel
2020-06-17 2:01 ` Martin K. Petersen
2020-06-15 23:34 ` [PATCH 4/5] nvme: support for multi-command set effects Keith Busch
2020-06-16 10:34 ` Javier González
2020-06-16 16:03 ` Martin K. Petersen
2020-06-15 23:34 ` [PATCH 5/5] nvme: support for zoned namespaces Keith Busch
2020-06-16 10:41 ` Javier González
2020-06-16 11:18 ` Matias Bjørling
2020-06-16 12:00 ` Javier González
2020-06-16 12:06 ` Matias Bjørling
2020-06-16 12:24 ` Javier González
2020-06-16 12:27 ` Matias Bjørling
2020-06-16 12:35 ` Damien Le Moal
[not found] ` <CGME20200616130815uscas1p1be34e5fceaa548eac31fb30790a689d4@uscas1p1.samsung.com>
2020-06-16 13:08 ` Judy Brock
2020-06-16 13:32 ` Matias Bjørling
2020-06-16 13:34 ` Damien Le Moal
2020-06-16 14:16 ` Javier González
2020-06-16 14:42 ` Damien Le Moal
2020-06-16 15:02 ` Javier González
2020-06-16 15:20 ` Matias Bjørling
2020-06-16 16:03 ` Javier González
2020-06-16 16:07 ` Matias Bjorling
2020-06-16 16:21 ` Javier González
2020-06-16 16:25 ` Matias Bjørling
2020-06-16 15:48 ` Keith Busch
2020-06-16 15:55 ` Javier González
2020-06-16 16:04 ` Matias Bjorling
2020-06-16 16:07 ` Keith Busch
2020-06-16 16:13 ` Javier González
2020-06-17 0:38 ` Damien Le Moal
2020-06-17 6:18 ` Javier González
2020-06-17 6:54 ` Damien Le Moal
2020-06-17 7:11 ` Javier González
2020-06-17 7:29 ` Damien Le Moal
2020-06-17 7:34 ` Javier González
2020-06-17 0:14 ` Damien Le Moal
2020-06-17 6:09 ` Javier González
2020-06-17 6:47 ` Damien Le Moal
2020-06-17 7:02 ` Javier González
2020-06-17 7:24 ` Damien Le Moal
2020-06-17 7:29 ` Javier González
[not found] ` <CGME20200616123503uscas1p22ce22054a1b4152a20437b5abdd55119@uscas1p2.samsung.com>
2020-06-16 12:35 ` Judy Brock
2020-06-16 12:37 ` Damien Le Moal
2020-06-16 12:37 ` Matias Bjørling
2020-06-16 13:12 ` Judy Brock
2020-06-16 13:18 ` Judy Brock
2020-06-16 13:32 ` Judy Brock
2020-06-16 13:39 ` Damien Le Moal
2020-06-17 7:43 ` Christoph Hellwig
2020-06-17 12:01 ` Martin K. Petersen
2020-06-17 15:00 ` Javier González
2020-06-17 14:42 ` Javier González
2020-06-17 17:57 ` Matias Bjørling
2020-06-17 18:28 ` Javier González
2020-06-17 18:55 ` Matias Bjorling
2020-06-17 19:09 ` Javier González
2020-06-17 19:23 ` Matias Bjørling
2020-06-17 19:40 ` Javier González
2020-06-17 23:44 ` Heiner Litz
2020-06-18 1:55 ` Keith Busch
2020-06-18 4:24 ` Heiner Litz
2020-06-18 5:15 ` Damien Le Moal
2020-06-18 20:47 ` Heiner Litz
2020-06-18 21:04 ` Matias Bjorling
2020-06-18 21:19 ` Keith Busch
2020-06-18 22:05 ` Heiner Litz
2020-06-19 0:57 ` Damien Le Moal
2020-06-19 10:29 ` Matias Bjorling
2020-06-19 18:08 ` Heiner Litz
2020-06-19 18:10 ` Keith Busch
2020-06-19 18:17 ` Heiner Litz
2020-06-19 18:22 ` Keith Busch [this message]
2020-06-19 18:25 ` Matias Bjørling
2020-06-19 18:40 ` Heiner Litz
2020-06-19 18:18 ` Matias Bjørling
2020-06-20 6:33 ` Christoph Hellwig
2020-06-20 17:52 ` Heiner Litz
2022-03-02 21:11 ` Luis Chamberlain
2020-06-17 2:08 ` Martin K. Petersen
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