From: Kanchan Joshi <[email protected]>
To: Jens Axboe <[email protected]>
Cc: Sagi Grimberg <[email protected]>,
[email protected], [email protected], [email protected],
[email protected], [email protected],
[email protected], [email protected],
[email protected], [email protected]
Subject: Re: [PATCH for-next 3/4] io_uring: grow a field in struct io_uring_cmd
Date: Tue, 12 Jul 2022 17:10:34 +0530 [thread overview]
Message-ID: <20220712114034.GB4465@test-zns> (raw)
In-Reply-To: <[email protected]>
[-- Attachment #1: Type: text/plain, Size: 1815 bytes --]
On Mon, Jul 11, 2022 at 12:24:42PM -0600, Jens Axboe wrote:
>On 7/11/22 12:22 PM, Sagi Grimberg wrote:
>>
>>>>> Use the leftover space to carve 'next' field that enables linking of
>>>>> io_uring_cmd structs. Also introduce a list head and few helpers.
>>>>>
>>>>> This is in preparation to support nvme-mulitpath, allowing multiple
>>>>> uring passthrough commands to be queued.
>>>>
>>>> It's not clear to me why we need linking at that level?
>>>
>>> I think the attempt is to allow something like blk_steal_bios that
>>> nvme leverages for io_uring_cmd(s).
>>
>> I'll rephrase because now that I read it, I think my phrasing is
>> confusing.
>>
>> I think the attempt is to allow something like blk_steal_bios that
>> nvme leverages, but for io_uring_cmd(s). Essentially allow io_uring_cmd
>> to be linked in a requeue_list.
>
>I see. I wonder if there's some other way we can accomplish that, so we
>don't have to shrink the current space. io_kiocb already support
>linking, so seems like that should be workable.
>
>>> nvme failover steals all the bios from requests that fail (and should
>>> failover) and puts them on a requeue list, and then schedules
>>> a work that takes these bios one-by-one and submits them on a different
>>> bottom namespace (see nvme_failover_req/nvme_requeue_work).
>>
>> Maybe if io_kiocb could exposed to nvme, and it had some generic space
>> that nvme could use, that would work as well...
>
>It will be more exposed in 5.20, but passthrough is already using the
>per-op allotted space in the io_kiocb. But as mentioned above, there's
>already linking support between io_kiocbs, and that is likely what
>should be used here too.
>
io_kiocb linking is used if user-space wants to link SQEs for any
ordering. If we go this route, we give up that feature for
uring-command SQEs.
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next prev parent reply other threads:[~2022-07-12 11:46 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20220711110753epcas5p4169b9e288d15ca35740dbb66a6f6983a@epcas5p4.samsung.com>
2022-07-11 11:01 ` [PATCH for-next 0/4] nvme-multipathing for uring-passthrough Kanchan Joshi
[not found] ` <CGME20220711110800epcas5p3d338dd486fd778c5ba5bfe93a91ec8bd@epcas5p3.samsung.com>
2022-07-11 11:01 ` [PATCH for-next 1/4] io_uring, nvme: rename a function Kanchan Joshi
2022-07-14 13:55 ` Ming Lei
[not found] ` <CGME20220711110812epcas5p33aa90b23aa62fb11722aa8195754becf@epcas5p3.samsung.com>
2022-07-11 11:01 ` [PATCH for-next 2/4] nvme: compact nvme_uring_cmd_pdu struct Kanchan Joshi
2022-07-12 6:32 ` Christoph Hellwig
[not found] ` <CGME20220711110824epcas5p22c8e945cb8c3c3ac46c8c2b5ab55db9b@epcas5p2.samsung.com>
2022-07-11 11:01 ` [PATCH for-next 3/4] io_uring: grow a field in struct io_uring_cmd Kanchan Joshi
2022-07-11 17:00 ` Sagi Grimberg
2022-07-11 17:19 ` Jens Axboe
2022-07-11 17:18 ` Jens Axboe
2022-07-11 17:55 ` Sagi Grimberg
2022-07-11 18:22 ` Sagi Grimberg
2022-07-11 18:24 ` Jens Axboe
2022-07-11 18:58 ` Sagi Grimberg
2022-07-12 11:40 ` Kanchan Joshi [this message]
2022-07-14 3:40 ` Ming Lei
2022-07-14 8:19 ` Kanchan Joshi
2022-07-14 15:30 ` Daniel Wagner
2022-07-15 11:07 ` Kanchan Joshi
2022-07-18 9:03 ` Daniel Wagner
[not found] ` <CGME20220711110827epcas5p3fd81f142f55ca3048abc38a9ef0d0089@epcas5p3.samsung.com>
2022-07-11 11:01 ` [PATCH for-next 4/4] nvme-multipath: add multipathing for uring-passthrough commands Kanchan Joshi
2022-07-11 13:51 ` Sagi Grimberg
2022-07-11 15:12 ` Stefan Metzmacher
2022-07-11 16:58 ` Sagi Grimberg
2022-07-11 18:54 ` Kanchan Joshi
2022-07-11 18:37 ` Kanchan Joshi
2022-07-11 19:56 ` Sagi Grimberg
2022-07-12 4:23 ` Kanchan Joshi
2022-07-12 21:26 ` Sagi Grimberg
2022-07-13 5:37 ` Kanchan Joshi
2022-07-13 9:03 ` Sagi Grimberg
2022-07-13 11:28 ` Kanchan Joshi
2022-07-13 12:17 ` Sagi Grimberg
2022-07-14 15:14 ` Ming Lei
2022-07-14 23:05 ` Kanchan Joshi
2022-07-15 1:35 ` Ming Lei
2022-07-15 1:46 ` Ming Lei
2022-07-15 4:24 ` Kanchan Joshi
2022-07-12 6:52 ` Christoph Hellwig
2022-07-12 11:33 ` Kanchan Joshi
2022-07-12 20:13 ` Sagi Grimberg
2022-07-13 5:36 ` Christoph Hellwig
2022-07-13 8:04 ` Sagi Grimberg
2022-07-13 10:12 ` Christoph Hellwig
2022-07-13 11:00 ` Sagi Grimberg
2022-07-13 11:28 ` Christoph Hellwig
2022-07-13 12:16 ` Sagi Grimberg
2022-07-13 11:49 ` Hannes Reinecke
2022-07-13 12:43 ` Sagi Grimberg
2022-07-13 13:30 ` Hannes Reinecke
2022-07-13 13:41 ` Sagi Grimberg
2022-07-13 14:07 ` Hannes Reinecke
2022-07-13 15:59 ` Sagi Grimberg
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