From: Hannes Reinecke <hare@suse.de>
To: Nitesh Shetty <nj.shetty@samsung.com>,
Jens Axboe <axboe@kernel.dk>, Jonathan Corbet <corbet@lwn.net>,
Alasdair Kergon <agk@redhat.com>,
Mike Snitzer <snitzer@kernel.org>,
dm-devel@redhat.com, Keith Busch <kbusch@kernel.org>,
Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>,
Chaitanya Kulkarni <kch@nvidia.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Christian Brauner <brauner@kernel.org>
Cc: martin.petersen@oracle.com, mcgrof@kernel.org,
gost.dev@samsung.com, Vincent Fu <vincent.fu@samsung.com>,
Anuj Gupta <anuj20.g@samsung.com>,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-doc@vger.kernel.org, linux-nvme@lists.infradead.org,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH v15 04/12] block: add emulation for copy
Date: Fri, 8 Sep 2023 08:06:38 +0200 [thread overview]
Message-ID: <e6fc7e65-ad31-4ca2-8b1b-4d97ba32926e@suse.de> (raw)
In-Reply-To: <20230906163844.18754-5-nj.shetty@samsung.com>
On 9/6/23 18:38, Nitesh Shetty wrote:
> For the devices which does not support copy, copy emulation is added.
> It is required for in-kernel users like fabrics, where file descriptor is
> not available and hence they can't use copy_file_range.
> Copy-emulation is implemented by reading from source into memory and
> writing to the corresponding destination.
> Also emulation can be used, if copy offload fails or partially completes.
> At present in kernel user of emulation is NVMe fabrics.
>
Leave out the last sentence; I really would like to see it enabled for
SCSI, too (we do have copy offload commands for SCSI ...).
And it raises all the questions which have bogged us down right from the
start: where is the point in calling copy offload if copy offload is not
implemented or slower than copying it by hand?
And how can the caller differentiate whether copy offload bring a
benefit to him?
IOW: wouldn't it be better to return -EOPNOTSUPP if copy offload is not
available?
Cheers,
Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
hare@suse.de +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Ivo Totev, Andrew
Myers, Andrew McDonald, Martje Boudien Moerman
next prev parent reply other threads:[~2023-09-08 6:06 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20230906164238epcas5p4a511a029fb8ae8bbc36b750712ad64d5@epcas5p4.samsung.com>
2023-09-06 16:38 ` [PATCH v15 00/12] Implement copy offload support Nitesh Shetty
2023-09-06 16:38 ` [PATCH v15 01/12] block: Introduce queue limits and sysfs for copy-offload support Nitesh Shetty
2023-09-07 18:38 ` Luis Chamberlain
2023-09-06 16:38 ` [PATCH v15 02/12] Add infrastructure for copy offload in block and request layer Nitesh Shetty
2023-09-07 5:39 ` Hannes Reinecke
2023-09-07 7:09 ` Nitesh Shetty
2023-09-06 16:38 ` [PATCH v15 03/12] block: add copy offload support Nitesh Shetty
2023-09-07 5:49 ` Hannes Reinecke
2023-09-07 7:16 ` Nitesh Shetty
2023-09-08 5:55 ` Hannes Reinecke
2023-09-06 16:38 ` [PATCH v15 04/12] block: add emulation for copy Nitesh Shetty
2023-09-08 6:06 ` Hannes Reinecke [this message]
2023-09-11 7:09 ` Nitesh Shetty
2023-09-11 7:39 ` Hannes Reinecke
2023-09-11 10:20 ` Nitesh Shetty
2023-09-06 16:38 ` [PATCH v15 05/12] fs/read_write: Enable copy_file_range for block device Nitesh Shetty
2023-09-08 6:07 ` Hannes Reinecke
2023-09-06 16:38 ` [PATCH v15 06/12] fs, block: copy_file_range for def_blk_ops for direct " Nitesh Shetty
2023-09-08 6:08 ` Hannes Reinecke
2023-09-06 16:38 ` [PATCH v15 07/12] nvme: add copy offload support Nitesh Shetty
2023-09-08 6:09 ` Hannes Reinecke
2023-09-06 16:38 ` [PATCH v15 08/12] nvmet: add copy command support for bdev and file ns Nitesh Shetty
2023-09-08 6:11 ` Hannes Reinecke
2023-09-06 16:38 ` [PATCH v15 09/12] dm: Add support for copy offload Nitesh Shetty
2023-09-08 6:13 ` Hannes Reinecke
2023-09-11 7:07 ` Nitesh Shetty
2023-09-11 7:45 ` Hannes Reinecke
2023-09-06 16:38 ` [PATCH v15 10/12] dm: Enable copy offload for dm-linear target Nitesh Shetty
2023-09-08 6:14 ` Hannes Reinecke
2023-09-06 16:38 ` [PATCH v15 11/12] null: Enable trace capability for null block Nitesh Shetty
2023-09-08 6:14 ` Hannes Reinecke
2023-09-06 16:38 ` [PATCH v15 12/12] null_blk: add support for copy offload Nitesh Shetty
2023-09-06 22:01 ` kernel test robot
2023-09-06 22:58 ` kernel test robot
2023-09-08 6:16 ` Hannes Reinecke
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