From: Keith Busch <kbusch@kernel.org>
To: Tim Walker <tim.t.walker@seagate.com>
Cc: Damien Le Moal <Damien.LeMoal@wdc.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
linux-scsi <linux-scsi@vger.kernel.org>,
"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
Ming Lei <ming.lei@redhat.com>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
Hannes Reinecke <hare@suse.de>
Subject: Re: [LSF/MM/BPF TOPIC] NVMe HDD
Date: Thu, 20 Feb 2020 05:50:52 +0900 [thread overview]
Message-ID: <20200219205052.GB28509@redsun51.ssa.fujisawa.hgst.com> (raw)
In-Reply-To: <CANo=J14GM=Uu7qWirtvgzjEKVCzLV0nZLOOPqD9M+nwOKrv7yQ@mail.gmail.com>
On Wed, Feb 19, 2020 at 11:28:46AM -0500, Tim Walker wrote:
> Hi Ming-
>
> >Will NVMe HDD support multiple NS?
>
> At this point it doesn't seem like an NVMe HDD could benefit from
> multiple namespaces. However, a multiple actuator HDD can present the
> actuators as independent channels that are capable of independent
> media access. It seems that we would want them on separate namespaces,
> or sets. I'd like to discuss the pros and cons of each, and which
> would be better for system integration.
If NVM Sets are not implemented, the host is not aware of resource
separatation for each namespace.
If you implement NVM Sets, two namespaces in different sets tells the host
that the device has a backend resource partition (logical or physical)
such that processing commands for one namespace will not affect the
processing capabilities of the other. Sets define "noisy neighbor"
domains.
Dual actuators sound like you have independent resources appropriate to
report as NVM Sets, but that may depend on other implementation details.
The NVMe specification does not go far enough, though, since IO queues
are always a shared resource. The host may implement a different IO
queue policy such that they're not shared (you'd need at least one IO
queue per set), but we don't currently do that.
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next prev parent reply other threads:[~2020-02-19 20:51 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-10 19:20 [LSF/MM/BPF TOPIC] NVMe HDD Tim Walker
2020-02-10 20:43 ` Keith Busch
2020-02-10 22:25 ` Finn Thain
2020-02-11 12:28 ` Ming Lei
2020-02-11 19:01 ` Tim Walker
2020-02-12 1:47 ` Damien Le Moal
2020-02-12 22:03 ` Ming Lei
2020-02-13 2:40 ` Damien Le Moal
2020-02-13 7:53 ` Ming Lei
2020-02-13 8:24 ` Damien Le Moal
2020-02-13 8:34 ` Ming Lei
2020-02-13 16:30 ` Keith Busch
2020-02-14 0:40 ` Ming Lei
2020-02-13 3:02 ` Martin K. Petersen
2020-02-13 3:12 ` Tim Walker
2020-02-13 4:17 ` Martin K. Petersen
2020-02-14 7:32 ` Hannes Reinecke
2020-02-14 14:40 ` Keith Busch
2020-02-14 16:04 ` Hannes Reinecke
2020-02-14 17:05 ` Keith Busch
2020-02-18 15:54 ` Tim Walker
2020-02-18 17:41 ` Keith Busch
2020-02-18 17:52 ` James Smart
2020-02-19 1:31 ` Ming Lei
2020-02-19 1:53 ` Damien Le Moal
2020-02-19 2:15 ` Ming Lei
2020-02-19 2:32 ` Damien Le Moal
2020-02-19 2:56 ` Tim Walker
2020-02-19 16:28 ` Tim Walker
2020-02-19 20:50 ` Keith Busch [this message]
2020-02-14 0:35 ` Ming Lei
2020-02-12 21:52 ` Ming Lei
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