From: "Javier González" <javier@javigon.com>
To: Max Gurtovoy <mgurtovoy@nvidia.com>
Cc: Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com>,
SelvaKumar S <selvakuma.s1@samsung.com>,
linux-nvme@lists.infradead.org, axboe@kernel.dk,
Damien Le Moal <damien.lemoal@wdc.com>,
kch@kernel.org, sagi@grimberg.me, snitzer@redhat.com,
selvajove@gmail.com, linux-kernel@vger.kernel.org,
nj.shetty@samsung.com, linux-block@vger.kernel.org,
linux-fsdevel@vger.kernel.org, dm-devel@redhat.com,
joshi.k@samsung.com, kbusch@kernel.org, joshiiitr@gmail.com,
hch@lst.de
Subject: Re: [RFC PATCH v5 0/4] add simple copy support
Date: Sun, 11 Apr 2021 21:26:41 +0200 [thread overview]
Message-ID: <20210411192641.ya6ntxannk3gjyl5@mpHalley.localdomain> (raw)
In-Reply-To: <c7848f1c-c2c1-6955-bf20-f413a44f9969@nvidia.com>
On 11.04.2021 12:10, Max Gurtovoy wrote:
>
>On 4/10/2021 9:32 AM, Javier González wrote:
>>>On 10 Apr 2021, at 02.30, Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com> wrote:
>>>
>>>On 4/9/21 17:22, Max Gurtovoy wrote:
>>>>>On 2/19/2021 2:45 PM, SelvaKumar S wrote:
>>>>>This patchset tries to add support for TP4065a ("Simple Copy Command"),
>>>>>v2020.05.04 ("Ratified")
>>>>>
>>>>>The Specification can be found in following link.
>>>>>https://nvmexpress.org/wp-content/uploads/NVM-Express-1.4-Ratified-TPs-1.zip
>>>>>
>>>>>Simple copy command is a copy offloading operation and is used to copy
>>>>>multiple contiguous ranges (source_ranges) of LBA's to a single destination
>>>>>LBA within the device reducing traffic between host and device.
>>>>>
>>>>>This implementation doesn't add native copy offload support for stacked
>>>>>devices rather copy offload is done through emulation. Possible use
>>>>>cases are F2FS gc and BTRFS relocation/balance.
>>>>>
>>>>>*blkdev_issue_copy* takes source bdev, no of sources, array of source
>>>>>ranges (in sectors), destination bdev and destination offset(in sectors).
>>>>>If both source and destination block devices are same and copy_offload = 1,
>>>>>then copy is done through native copy offloading. Copy emulation is used
>>>>>in other cases.
>>>>>
>>>>>As SCSI XCOPY can take two different block devices and no of source range is
>>>>>equal to 1, this interface can be extended in future to support SCSI XCOPY.
>>>>Any idea why this TP wasn't designed for copy offload between 2
>>>>different namespaces in the same controller ?
>>>Yes, it was the first attempt so to keep it simple.
>>>
>>>Further work is needed to add incremental TP so that we can also do a copy
>>>between the name-spaces of same controller (if we can't already) and to the
>>>namespaces that belongs to the different controller.
>>>
>>>>And a simple copy will be the case where the src_nsid == dst_nsid ?
>>>>
>>>>Also why there are multiple source ranges and only one dst range ? We
>>>>could add a bit to indicate if this range is src or dst..
>>One of the target use cases was ZNS in order to avoid fabric transfers during host GC. You can see how this plays well with several zone ranges and a single zone destination.
>>
>>If we start getting support in Linux through the different past copy offload efforts, I’m sure we can extend this TP in the future.
>
>But the "copy" command IMO is more general than the ZNS GC case, that
>can be a private case of copy, isn't it ?
It applies to any namespace type, so yes. I just wanted to give you the
background for the current "simple" scope through one of the use cases
that was in mind.
>We can get a big benefit of offloading the data copy from one ns to
>another in the same controller and even in different controllers in
>the same subsystem.
Definitely.
>
>Do you think the extension should be to "copy" command or to create a
>new command "x_copy" for copying to different destination ns ?
I believe there is space for extensions to simple copy. But given the
experience with XCOPY, I can imagine that changes will be incremental,
based on very specific use cases.
I think getting support upstream and bringing deployed cases is a very
good start.
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next prev parent reply other threads:[~2021-04-11 19:27 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20210219124555epcas5p1334e7c4d64ada5dc4a2ca0feb48c1d44@epcas5p1.samsung.com>
2021-02-19 12:45 ` [RFC PATCH v5 0/4] add simple copy support SelvaKumar S
[not found] ` <CGME20210219124559epcas5p41da46f1c248e334953d407a154697903@epcas5p4.samsung.com>
2021-02-19 12:45 ` [RFC PATCH v5 1/4] block: make bio_map_kern() non static SelvaKumar S
[not found] ` <CGME20210219124603epcas5p33add0f2c1781b2a4d71bf30c9e1ac647@epcas5p3.samsung.com>
2021-02-19 12:45 ` [RFC PATCH v5 2/4] block: add simple copy support SelvaKumar S
2021-02-20 4:59 ` Damien Le Moal
2021-04-07 11:32 ` Selva Jove
2021-04-12 0:24 ` Damien Le Moal
2021-04-12 14:34 ` Selva Jove
2021-04-13 0:32 ` Damien Le Moal
2021-04-14 6:58 ` Selva Jove
[not found] ` <CGME20210219124608epcas5p2a673f9e00c3e7b5352f115497b0e2d98@epcas5p2.samsung.com>
2021-02-19 12:45 ` [RFC PATCH v5 3/4] nvme: " SelvaKumar S
2021-02-20 3:36 ` Matthew Wilcox
2021-02-22 15:57 ` Selva Jove
[not found] ` <CGME20210219124611epcas5p1c775b63b537e75da161556e375fcf05e@epcas5p1.samsung.com>
2021-02-19 12:45 ` [RFC PATCH v5 4/4] dm kcopyd: add simple copy offload support SelvaKumar S
2021-02-20 18:01 ` [RFC PATCH v5 0/4] add simple copy support David Laight
2021-02-20 19:08 ` Matthew Wilcox
2021-02-20 19:19 ` Keith Busch
2021-02-21 23:52 ` Dave Chinner
2021-02-23 9:14 ` Selva Jove
2021-02-22 1:31 ` Ming Lei
2021-02-22 6:52 ` Su Yue
2021-02-23 9:00 ` Selva Jove
2021-04-10 0:21 ` Max Gurtovoy
2021-04-10 0:29 ` Chaitanya Kulkarni
2021-04-10 6:32 ` Javier González
2021-04-11 9:10 ` Max Gurtovoy
2021-04-11 19:26 ` Javier González [this message]
2021-04-13 15:38 ` Max Gurtovoy
2021-04-13 18:25 ` Javier González
2021-04-13 18:36 ` Chaitanya Kulkarni
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