From: Heiner Litz <hlitz@ucsc.edu>
To: "Matias Bjørling" <mb@lightnvm.io>
Cc: "Keith Busch" <kbusch@kernel.org>,
"Matias Bjorling" <Matias.Bjorling@wdc.com>,
"Damien Le Moal" <Damien.LeMoal@wdc.com>,
"Javier González" <javier@javigon.com>,
"Christoph Hellwig" <hch@lst.de>,
"Keith Busch" <Keith.Busch@wdc.com>,
"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"Sagi Grimberg" <sagi@grimberg.me>,
"Jens Axboe" <axboe@kernel.dk>,
"Hans Holmberg" <Hans.Holmberg@wdc.com>,
"Dmitry Fomichev" <Dmitry.Fomichev@wdc.com>,
"Ajay Joshi" <Ajay.Joshi@wdc.com>,
"Aravind Ramesh" <Aravind.Ramesh@wdc.com>,
"Niklas Cassel" <Niklas.Cassel@wdc.com>,
"Judy Brock" <judy.brock@samsung.com>
Subject: Re: [PATCH 5/5] nvme: support for zoned namespaces
Date: Fri, 19 Jun 2020 11:40:04 -0700 [thread overview]
Message-ID: <CAJbgVnXodOZg_UAe0s5qu_t8rKu9KU=zt4qhfDpnNi0NBvbLKg@mail.gmail.com> (raw)
In-Reply-To: <61101beb-de48-7556-160f-cfd45bf72868@lightnvm.io>
That makes sense. We are generally paying a high price for
implementing in-order interfaces over out-of-order communication
channels (e.g. TCP buffers) and append() seems to be a much more
lightweight solution.
On Fri, Jun 19, 2020 at 11:25 AM Matias Bjørling <mb@lightnvm.io> wrote:
>
> On 19/06/2020 20.17, 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.
> It doesn't. Out of order delivery is not guaranteed in NVMe.
> > 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.
>
> That why zone append was introduced in ZNS. It removes this constraint,
> and makes it such that any process (or host) can write to a specific
> zone. It's neat! That is why the command was introduced.
>
> It is not only Linux specific - it applies to everyone that wants to use
> it. It is solving a fundamental distributed system problem, as it
> removes the need for fine-grained coordinating between process or host.
> It allows the SSD to coordinate data placement, which historically has
> been done by the host. It is awesome!
>
> >
> >>> The requirement of sequential writes basically imposes this
> >>> requirement. Append essentially a Linux specific fix on the ZNS level
> >>> and that enforcing ordering would be a cleaner way to enable QD>1.
>
>
WARNING: multiple messages have this Message-ID (diff)
From: Heiner Litz <hlitz@ucsc.edu>
To: "Matias Bjørling" <mb@lightnvm.io>
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>,
"Keith Busch" <kbusch@kernel.org>,
"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 11:40:04 -0700 [thread overview]
Message-ID: <CAJbgVnXodOZg_UAe0s5qu_t8rKu9KU=zt4qhfDpnNi0NBvbLKg@mail.gmail.com> (raw)
In-Reply-To: <61101beb-de48-7556-160f-cfd45bf72868@lightnvm.io>
That makes sense. We are generally paying a high price for
implementing in-order interfaces over out-of-order communication
channels (e.g. TCP buffers) and append() seems to be a much more
lightweight solution.
On Fri, Jun 19, 2020 at 11:25 AM Matias Bjørling <mb@lightnvm.io> wrote:
>
> On 19/06/2020 20.17, 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.
> It doesn't. Out of order delivery is not guaranteed in NVMe.
> > 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.
>
> That why zone append was introduced in ZNS. It removes this constraint,
> and makes it such that any process (or host) can write to a specific
> zone. It's neat! That is why the command was introduced.
>
> It is not only Linux specific - it applies to everyone that wants to use
> it. It is solving a fundamental distributed system problem, as it
> removes the need for fine-grained coordinating between process or host.
> It allows the SSD to coordinate data placement, which historically has
> been done by the host. It is awesome!
>
> >
> >>> The requirement of sequential writes basically imposes this
> >>> requirement. Append essentially a Linux specific fix on the ZNS level
> >>> and that enforcing ordering would be a cleaner way to enable QD>1.
>
>
_______________________________________________
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linux-nvme@lists.infradead.org
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next prev parent reply other threads:[~2020-06-19 18:40 UTC|newest]
Thread overview: 192+ 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 ` Keith Busch
2020-06-15 23:34 ` [PATCH 1/5] block: add capacity field to zone descriptors Keith Busch
2020-06-15 23:34 ` Keith Busch
2020-06-15 23:49 ` Chaitanya Kulkarni
2020-06-15 23:49 ` Chaitanya Kulkarni
2020-06-16 10:28 ` Javier González
2020-06-16 10:28 ` Javier González
2020-06-16 13:47 ` Daniel Wagner
2020-06-16 13:47 ` Daniel Wagner
2020-06-16 13:54 ` Johannes Thumshirn
2020-06-16 13:54 ` Johannes Thumshirn
2020-06-16 15:41 ` Martin K. Petersen
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 23:34 ` Keith Busch
2020-06-15 23:46 ` Chaitanya Kulkarni
2020-06-15 23:46 ` Chaitanya Kulkarni
2020-06-16 14:18 ` Daniel Wagner
2020-06-16 14:18 ` Daniel Wagner
2020-06-16 15:48 ` Martin K. Petersen
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
2020-06-15 23:34 ` Keith Busch
2020-06-16 10:33 ` Javier González
2020-06-16 10:33 ` Javier González
2020-06-16 17:14 ` Niklas Cassel
2020-06-16 17:14 ` Niklas Cassel
2020-06-16 15:58 ` Martin K. Petersen
2020-06-16 15:58 ` Martin K. Petersen
2020-06-16 17:01 ` Keith Busch
2020-06-16 17:01 ` Keith Busch
2020-06-17 9:50 ` Niklas Cassel
2020-06-17 9:50 ` Niklas Cassel
2020-06-16 17:06 ` Niklas Cassel
2020-06-16 17:06 ` Niklas Cassel
2020-06-17 2:01 ` Martin K. Petersen
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
2020-06-15 23:34 ` Keith Busch
2020-06-16 10:34 ` Javier González
2020-06-16 10:34 ` Javier González
2020-06-16 16:03 ` Martin K. Petersen
2020-06-16 16:03 ` Martin K. Petersen
2020-06-15 23:34 ` [PATCH 5/5] nvme: support for zoned namespaces Keith Busch
2020-06-15 23:34 ` Keith Busch
2020-06-16 10:41 ` Javier González
2020-06-16 10:41 ` Javier González
2020-06-16 11:18 ` Matias Bjørling
2020-06-16 11:18 ` Matias Bjørling
2020-06-16 12:00 ` Javier González
2020-06-16 12:00 ` Javier González
2020-06-16 12:06 ` Matias Bjørling
2020-06-16 12:06 ` Matias Bjørling
2020-06-16 12:24 ` Javier González
2020-06-16 12:24 ` Javier González
2020-06-16 12:27 ` Matias Bjørling
2020-06-16 12:27 ` Matias Bjørling
2020-06-16 12:35 ` Damien Le Moal
2020-06-16 12:35 ` Damien Le Moal
[not found] ` <CGME20200616130815uscas1p1be34e5fceaa548eac31fb30790a689d4@uscas1p1.samsung.com>
2020-06-16 13:08 ` Judy Brock
2020-06-16 13:08 ` Judy Brock
2020-06-16 13:32 ` Matias Bjørling
2020-06-16 13:32 ` Matias Bjørling
2020-06-16 13:34 ` Damien Le Moal
2020-06-16 13:34 ` Damien Le Moal
2020-06-16 14:16 ` Javier González
2020-06-16 14:16 ` Javier González
2020-06-16 14:42 ` Damien Le Moal
2020-06-16 14:42 ` Damien Le Moal
2020-06-16 15:02 ` Javier González
2020-06-16 15:02 ` Javier González
2020-06-16 15:20 ` Matias Bjørling
2020-06-16 15:20 ` Matias Bjørling
2020-06-16 16:03 ` Javier González
2020-06-16 16:03 ` Javier González
2020-06-16 16:07 ` Matias Bjorling
2020-06-16 16:07 ` Matias Bjorling
2020-06-16 16:21 ` Javier González
2020-06-16 16:21 ` Javier González
2020-06-16 16:25 ` Matias Bjørling
2020-06-16 16:25 ` Matias Bjørling
2020-06-16 15:48 ` Keith Busch
2020-06-16 15:48 ` Keith Busch
2020-06-16 15:55 ` Javier González
2020-06-16 15:55 ` Javier González
2020-06-16 16:04 ` Matias Bjorling
2020-06-16 16:04 ` Matias Bjorling
2020-06-16 16:07 ` Keith Busch
2020-06-16 16:07 ` Keith Busch
2020-06-16 16:13 ` Javier González
2020-06-16 16:13 ` Javier González
2020-06-17 0:38 ` Damien Le Moal
2020-06-17 0:38 ` Damien Le Moal
2020-06-17 6:18 ` Javier González
2020-06-17 6:18 ` Javier González
2020-06-17 6:54 ` Damien Le Moal
2020-06-17 6:54 ` Damien Le Moal
2020-06-17 7:11 ` Javier González
2020-06-17 7:11 ` Javier González
2020-06-17 7:29 ` Damien Le Moal
2020-06-17 7:29 ` Damien Le Moal
2020-06-17 7:34 ` Javier González
2020-06-17 7:34 ` Javier González
2020-06-17 0:14 ` Damien Le Moal
2020-06-17 0:14 ` Damien Le Moal
2020-06-17 6:09 ` Javier González
2020-06-17 6:09 ` Javier González
2020-06-17 6:47 ` Damien Le Moal
2020-06-17 6:47 ` Damien Le Moal
2020-06-17 7:02 ` Javier González
2020-06-17 7:02 ` Javier González
2020-06-17 7:24 ` Damien Le Moal
2020-06-17 7:24 ` Damien Le Moal
2020-06-17 7:29 ` Javier González
2020-06-17 7:29 ` Javier González
[not found] ` <CGME20200616123503uscas1p22ce22054a1b4152a20437b5abdd55119@uscas1p2.samsung.com>
2020-06-16 12:35 ` Judy Brock
2020-06-16 12:35 ` Judy Brock
2020-06-16 12:37 ` Damien Le Moal
2020-06-16 12:37 ` Damien Le Moal
2020-06-16 12:37 ` Matias Bjørling
2020-06-16 12:37 ` Matias Bjørling
2020-06-16 13:12 ` Judy Brock
2020-06-16 13:12 ` Judy Brock
2020-06-16 13:18 ` Judy Brock
2020-06-16 13:18 ` Judy Brock
2020-06-16 13:32 ` Judy Brock
2020-06-16 13:32 ` Judy Brock
2020-06-16 13:39 ` Damien Le Moal
2020-06-16 13:39 ` Damien Le Moal
2020-06-17 7:43 ` Christoph Hellwig
2020-06-17 7:43 ` Christoph Hellwig
2020-06-17 12:01 ` Martin K. Petersen
2020-06-17 12:01 ` Martin K. Petersen
2020-06-17 15:00 ` Javier González
2020-06-17 15:00 ` Javier González
2020-06-17 14:42 ` Javier González
2020-06-17 14:42 ` Javier González
2020-06-17 17:57 ` Matias Bjørling
2020-06-17 17:57 ` Matias Bjørling
2020-06-17 18:28 ` Javier González
2020-06-17 18:28 ` Javier González
2020-06-17 18:55 ` Matias Bjorling
2020-06-17 18:55 ` Matias Bjorling
2020-06-17 19:09 ` Javier González
2020-06-17 19:09 ` Javier González
2020-06-17 19:23 ` Matias Bjørling
2020-06-17 19:23 ` Matias Bjørling
2020-06-17 19:40 ` Javier González
2020-06-17 19:40 ` Javier González
2020-06-17 23:44 ` Heiner Litz
2020-06-17 23:44 ` Heiner Litz
2020-06-18 1:55 ` Keith Busch
2020-06-18 1:55 ` Keith Busch
2020-06-18 4:24 ` Heiner Litz
2020-06-18 4:24 ` Heiner Litz
2020-06-18 5:15 ` Damien Le Moal
2020-06-18 5:15 ` Damien Le Moal
2020-06-18 20:47 ` Heiner Litz
2020-06-18 20:47 ` Heiner Litz
2020-06-18 21:04 ` Matias Bjorling
2020-06-18 21:04 ` Matias Bjorling
2020-06-18 21:19 ` Keith Busch
2020-06-18 21:19 ` Keith Busch
2020-06-18 22:05 ` Heiner Litz
2020-06-18 22:05 ` Heiner Litz
2020-06-19 0:57 ` Damien Le Moal
2020-06-19 0:57 ` Damien Le Moal
2020-06-19 10:29 ` Matias Bjorling
2020-06-19 10:29 ` Matias Bjorling
2020-06-19 18:08 ` Heiner Litz
2020-06-19 18:08 ` Heiner Litz
2020-06-19 18:10 ` Keith Busch
2020-06-19 18:10 ` Keith Busch
2020-06-19 18:17 ` Heiner Litz
2020-06-19 18:17 ` Heiner Litz
2020-06-19 18:22 ` Keith Busch
2020-06-19 18:22 ` Keith Busch
2020-06-19 18:25 ` Matias Bjørling
2020-06-19 18:25 ` Matias Bjørling
2020-06-19 18:40 ` Heiner Litz [this message]
2020-06-19 18:40 ` Heiner Litz
2020-06-19 18:18 ` Matias Bjørling
2020-06-19 18:18 ` Matias Bjørling
2020-06-20 6:33 ` Christoph Hellwig
2020-06-20 6:33 ` Christoph Hellwig
2020-06-20 17:52 ` Heiner Litz
2020-06-20 17:52 ` Heiner Litz
2020-06-22 14:01 ` Christoph Hellwig
2022-03-02 21:11 ` Luis Chamberlain
2020-06-17 2:08 ` Martin K. Petersen
2020-06-17 2:08 ` Martin K. Petersen
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