From: "Javier González" <javier@javigon.com>
To: Hannes Reinecke <hare@suse.de>
Cc: axboe@kernel.dk, damien.lemoal@wdc.com,
SelvaKumar S <selvakuma.s1@samsung.com>,
sagi@grimberg.me, snitzer@redhat.com, selvajove@gmail.com,
linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org,
nj.shetty@samsung.com, linux-block@vger.kernel.org,
dm-devel@redhat.com, Mikulas Patocka <mpatocka@redhat.com>,
joshi.k@samsung.com,
"Martin K. Petersen" <martin.petersen@oracle.com>,
kbusch@kernel.org, linux-scsi@vger.kernel.org,
Christoph Hellwig <hch@lst.de>,
Bart Van Assche <bvanassche@acm.org>
Subject: Re: [RFC PATCH v2 0/2] add simple copy support
Date: Mon, 7 Dec 2020 20:24:53 +0100 [thread overview]
Message-ID: <20201207192453.vc6clbdhz73hzs7l@mpHalley> (raw)
In-Reply-To: <01fe46ac-16a5-d4db-f23d-07a03d3935f3@suse.de>
On 07.12.2020 15:56, Hannes Reinecke wrote:
>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.
Good point. We can share some performance data on how Simple Copy scales
in terms of bw / latency and the CPU usage. Do you have anything else in
mind?
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next prev parent reply other threads:[~2020-12-07 19:25 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20201204094719epcas5p23b3c41223897de3840f92ae3c229cda5@epcas5p2.samsung.com>
2020-12-04 9:46 ` [RFC PATCH v2 0/2] add simple copy support SelvaKumar S
[not found] ` <CGME20201204094731epcas5p307fe5a0b9360c5057cd48e42c9300053@epcas5p3.samsung.com>
2020-12-04 9:46 ` [RFC PATCH v2 1/2] block: " SelvaKumar S
2020-12-09 4:19 ` [dm-devel] " Martin K. Petersen
2020-12-09 5:17 ` Damien Le Moal
[not found] ` <CGME20201204094747epcas5p121b6eccf78a29ed4cba7c22d6b42d160@epcas5p1.samsung.com>
2020-12-04 9:46 ` [RFC PATCH v2 2/2] nvme: " SelvaKumar S
2020-12-04 11:25 ` [RFC PATCH v2 0/2] " Damien Le Moal
2020-12-04 14:40 ` Keith Busch
2020-12-07 7:46 ` javier.gonz@samsung.com
2020-12-07 8:06 ` Damien Le Moal
2020-12-07 8:16 ` javier.gonz@samsung.com
2020-12-07 9:01 ` Damien Le Moal
2020-12-07 14:11 ` Christoph Hellwig
2020-12-07 14:56 ` Hannes Reinecke
2020-12-07 19:24 ` Javier González [this message]
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
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