From: Ming Lei <ming.lei@redhat.com>
To: Tim Walker <tim.t.walker@seagate.com>
Cc: linux-block@vger.kernel.org,
linux-scsi <linux-scsi@vger.kernel.org>,
linux-nvme@lists.infradead.org
Subject: Re: [LSF/MM/BPF TOPIC] NVMe HDD
Date: Tue, 11 Feb 2020 20:28:21 +0800 [thread overview]
Message-ID: <20200211122821.GA29811@ming.t460p> (raw)
In-Reply-To: <CANo=J14resJ4U1nufoiDq+ULd0k-orRCsYah8Dve-y8uCjA62Q@mail.gmail.com>
On Mon, Feb 10, 2020 at 02:20:10PM -0500, Tim Walker wrote:
> Background:
>
> NVMe specification has hardened over the decade and now NVMe devices
> are well integrated into our customers’ systems. As we look forward,
> moving HDDs to the NVMe command set eliminates the SAS IOC and driver
> stack, consolidating on a single access method for rotational and
> static storage technologies. PCIe-NVMe offers near-SATA interface
> costs, features and performance suitable for high-cap HDDs, and
> optimal interoperability for storage automation, tiering, and
> management. We will share some early conceptual results and proposed
> salient design goals and challenges surrounding an NVMe HDD.
HDD. performance is very sensitive to IO order. Could you provide some
background info about NVMe HDD? Such as:
- number of hw queues
- hw queue depth
- will NVMe sort/merge IO among all SQs or not?
>
>
> Discussion Proposal:
>
> We’d like to share our views and solicit input on:
>
> -What Linux storage stack assumptions do we need to be aware of as we
> develop these devices with drastically different performance
> characteristics than traditional NAND? For example, what schedular or
> device driver level changes will be needed to integrate NVMe HDDs?
IO merge is often important for HDD. IO merge is usually triggered when
.queue_rq() returns STS_RESOURCE, so far this condition won't be
triggered for NVMe SSD.
Also blk-mq kills BDI queue congestion and ioc batching, and causes
writeback performance regression[1][2].
What I am thinking is that if we need to switch to use independent IO
path for handling SSD and HDD. IO, given the two mediums are so
different from performance viewpoint.
[1] https://lore.kernel.org/linux-scsi/Pine.LNX.4.44L0.1909181213141.1507-100000@iolanthe.rowland.org/
[2] https://lore.kernel.org/linux-scsi/20191226083706.GA17974@ming.t460p/
Thanks,
Ming
WARNING: multiple messages have this Message-ID (diff)
From: Ming Lei <ming.lei@redhat.com>
To: Tim Walker <tim.t.walker@seagate.com>
Cc: linux-block@vger.kernel.org, linux-nvme@lists.infradead.org,
linux-scsi <linux-scsi@vger.kernel.org>
Subject: Re: [LSF/MM/BPF TOPIC] NVMe HDD
Date: Tue, 11 Feb 2020 20:28:21 +0800 [thread overview]
Message-ID: <20200211122821.GA29811@ming.t460p> (raw)
In-Reply-To: <CANo=J14resJ4U1nufoiDq+ULd0k-orRCsYah8Dve-y8uCjA62Q@mail.gmail.com>
On Mon, Feb 10, 2020 at 02:20:10PM -0500, Tim Walker wrote:
> Background:
>
> NVMe specification has hardened over the decade and now NVMe devices
> are well integrated into our customers’ systems. As we look forward,
> moving HDDs to the NVMe command set eliminates the SAS IOC and driver
> stack, consolidating on a single access method for rotational and
> static storage technologies. PCIe-NVMe offers near-SATA interface
> costs, features and performance suitable for high-cap HDDs, and
> optimal interoperability for storage automation, tiering, and
> management. We will share some early conceptual results and proposed
> salient design goals and challenges surrounding an NVMe HDD.
HDD. performance is very sensitive to IO order. Could you provide some
background info about NVMe HDD? Such as:
- number of hw queues
- hw queue depth
- will NVMe sort/merge IO among all SQs or not?
>
>
> Discussion Proposal:
>
> We’d like to share our views and solicit input on:
>
> -What Linux storage stack assumptions do we need to be aware of as we
> develop these devices with drastically different performance
> characteristics than traditional NAND? For example, what schedular or
> device driver level changes will be needed to integrate NVMe HDDs?
IO merge is often important for HDD. IO merge is usually triggered when
.queue_rq() returns STS_RESOURCE, so far this condition won't be
triggered for NVMe SSD.
Also blk-mq kills BDI queue congestion and ioc batching, and causes
writeback performance regression[1][2].
What I am thinking is that if we need to switch to use independent IO
path for handling SSD and HDD. IO, given the two mediums are so
different from performance viewpoint.
[1] https://lore.kernel.org/linux-scsi/Pine.LNX.4.44L0.1909181213141.1507-100000@iolanthe.rowland.org/
[2] https://lore.kernel.org/linux-scsi/20191226083706.GA17974@ming.t460p/
Thanks,
Ming
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next prev parent reply other threads:[~2020-02-11 12:28 UTC|newest]
Thread overview: 64+ 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 19:20 ` Tim Walker
2020-02-10 20:43 ` Keith Busch
2020-02-10 20:43 ` Keith Busch
2020-02-10 22:25 ` Finn Thain
2020-02-10 22:25 ` Finn Thain
2020-02-11 12:28 ` Ming Lei [this message]
2020-02-11 12:28 ` Ming Lei
2020-02-11 19:01 ` Tim Walker
2020-02-11 19:01 ` Tim Walker
2020-02-12 1:47 ` Damien Le Moal
2020-02-12 1:47 ` Damien Le Moal
2020-02-12 22:03 ` Ming Lei
2020-02-12 22:03 ` Ming Lei
2020-02-13 2:40 ` Damien Le Moal
2020-02-13 2:40 ` Damien Le Moal
2020-02-13 7:53 ` Ming Lei
2020-02-13 7:53 ` Ming Lei
2020-02-13 8:24 ` Damien Le Moal
2020-02-13 8:24 ` Damien Le Moal
2020-02-13 8:34 ` Ming Lei
2020-02-13 8:34 ` Ming Lei
2020-02-13 16:30 ` Keith Busch
2020-02-13 16:30 ` Keith Busch
2020-02-14 0:40 ` Ming Lei
2020-02-14 0:40 ` Ming Lei
2020-02-13 3:02 ` Martin K. Petersen
2020-02-13 3:02 ` Martin K. Petersen
2020-02-13 3:12 ` Tim Walker
2020-02-13 3:12 ` Tim Walker
2020-02-13 4:17 ` Martin K. Petersen
2020-02-13 4:17 ` Martin K. Petersen
2020-02-14 7:32 ` Hannes Reinecke
2020-02-14 7:32 ` Hannes Reinecke
2020-02-14 14:40 ` Keith Busch
2020-02-14 14:40 ` Keith Busch
2020-02-14 16:04 ` Hannes Reinecke
2020-02-14 16:04 ` Hannes Reinecke
2020-02-14 17:05 ` Keith Busch
2020-02-14 17:05 ` Keith Busch
2020-02-18 15:54 ` Tim Walker
2020-02-18 15:54 ` Tim Walker
2020-02-18 17:41 ` Keith Busch
2020-02-18 17:41 ` Keith Busch
2020-02-18 17:52 ` James Smart
2020-02-18 17:52 ` James Smart
2020-02-19 1:31 ` Ming Lei
2020-02-19 1:31 ` Ming Lei
2020-02-19 1:53 ` Damien Le Moal
2020-02-19 1:53 ` Damien Le Moal
2020-02-19 2:15 ` Ming Lei
2020-02-19 2:15 ` Ming Lei
2020-02-19 2:32 ` Damien Le Moal
2020-02-19 2:32 ` Damien Le Moal
2020-02-19 2:56 ` Tim Walker
2020-02-19 2:56 ` Tim Walker
2020-02-19 16:28 ` Tim Walker
2020-02-19 16:28 ` Tim Walker
2020-02-19 20:50 ` Keith Busch
2020-02-19 20:50 ` Keith Busch
2020-02-14 0:35 ` Ming Lei
2020-02-14 0:35 ` Ming Lei
2020-02-12 21:52 ` Ming Lei
2020-02-12 21:52 ` Ming Lei
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