From: Hannes Reinecke <hare@suse.de>
To: Christoph Hellwig <hch@lst.de>, SelvaKumar S <selvakuma.s1@samsung.com>
Cc: linux-nvme@lists.infradead.org, kbusch@kernel.org,
axboe@kernel.dk, damien.lemoal@wdc.com, sagi@grimberg.me,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
dm-devel@redhat.com, snitzer@redhat.com, selvajove@gmail.com,
nj.shetty@samsung.com, joshi.k@samsung.com,
javier.gonz@samsung.com,
"Martin K. Petersen" <martin.petersen@oracle.com>,
Bart Van Assche <bvanassche@acm.org>,
Mikulas Patocka <mpatocka@redhat.com>,
linux-scsi@vger.kernel.org
Subject: Re: [RFC PATCH v2 0/2] add simple copy support
Date: Mon, 7 Dec 2020 15:56:15 +0100 [thread overview]
Message-ID: <01fe46ac-16a5-d4db-f23d-07a03d3935f3@suse.de> (raw)
In-Reply-To: <20201207141123.GC31159@lst.de>
On 12/7/20 3:11 PM, Christoph Hellwig wrote:
> So, I'm really worried about:
>
> a) a good use case. GC in f2fs or btrfs seem like good use cases, as
> does accelating dm-kcopyd. I agree with Damien that lifting dm-kcopyd
> to common code would also be really nice. I'm not 100% sure it should
> be a requirement, but it sure would be nice to have
> I don't think just adding an ioctl is enough of a use case for complex
> kernel infrastructure.
> b) We had a bunch of different attempts at SCSI XCOPY support form IIRC
> Martin, Bart and Mikulas. I think we need to pull them into this
> discussion, and make sure whatever we do covers the SCSI needs.
>
And we shouldn't forget that the main issue which killed all previous
implementations was a missing QoS guarantee.
It's nice to have simply copy, but if the implementation is _slower_
than doing it by hand from the OS there is very little point in even
attempting to do so.
I can't see any provisions for that in the TPAR, leading me to the
assumption that NVMe simple copy will suffer from the same issue.
So if we can't address this I guess this attempt will fail, too.
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: Felix Imendörffer
next prev parent reply other threads:[~2020-12-07 14:57 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20201204094719epcas5p23b3c41223897de3840f92ae3c229cda5@epcas5p2.samsung.com>
[not found] ` <20201204094659.12732-1-selvakuma.s1@samsung.com>
2020-12-07 14:11 ` [RFC PATCH v2 0/2] add simple copy support Christoph Hellwig
2020-12-07 14:56 ` Hannes Reinecke [this message]
2020-12-07 19:24 ` Javier González
2020-12-08 8:40 ` Johannes Thumshirn
2020-12-08 12:22 ` Javier González
2020-12-08 12:37 ` Johannes Thumshirn
2020-12-08 13:13 ` Javier González
2020-12-08 13:24 ` Johannes Thumshirn
2020-12-09 9:17 ` Javier González
2020-12-15 23:45 ` Pavel Machek
2020-12-07 22:12 ` Douglas Gilbert
2020-12-08 6:44 ` Hannes Reinecke
2020-12-08 12:21 ` Javier González
2020-12-09 3:02 ` Martin K. Petersen
2020-12-07 19:14 ` Javier González
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=01fe46ac-16a5-d4db-f23d-07a03d3935f3@suse.de \
--to=hare@suse.de \
--cc=axboe@kernel.dk \
--cc=bvanassche@acm.org \
--cc=damien.lemoal@wdc.com \
--cc=dm-devel@redhat.com \
--cc=hch@lst.de \
--cc=javier.gonz@samsung.com \
--cc=joshi.k@samsung.com \
--cc=kbusch@kernel.org \
--cc=linux-block@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-nvme@lists.infradead.org \
--cc=linux-scsi@vger.kernel.org \
--cc=martin.petersen@oracle.com \
--cc=mpatocka@redhat.com \
--cc=nj.shetty@samsung.com \
--cc=sagi@grimberg.me \
--cc=selvajove@gmail.com \
--cc=selvakuma.s1@samsung.com \
--cc=snitzer@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).