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From: Pavel Begunkov <[email protected]>
To: Jens Axboe <[email protected]>, Ming Lei <[email protected]>
Cc: [email protected], [email protected],
	Uday Shankar <[email protected]>,
	Akilesh Kailash <[email protected]>
Subject: Re: [PATCH V8 0/8] io_uring: support sqe group and leased group kbuf
Date: Thu, 31 Oct 2024 13:25:24 +0000	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

On 10/30/24 02:43, Jens Axboe wrote:
> On 10/29/24 8:03 PM, Ming Lei wrote:
>> On Tue, Oct 29, 2024 at 03:26:37PM -0600, Jens Axboe wrote:
>>> On 10/29/24 2:06 PM, Jens Axboe wrote:
>>>> On 10/29/24 1:18 PM, Jens Axboe wrote:
...
>>> +	node->buf = imu;
>>> +	node->kbuf_fn = kbuf_fn;
>>> +	return node;
>>
>> Also this function needs to register the buffer to table with one
>> pre-defined buf index, then the following request can use it by
>> the way of io_prep_rw_fixed().
> 
> It should not register it with the table, the whole point is to keep
> this node only per-submission discoverable. If you're grabbing random
> request pages, then it very much is a bit finicky 

Registering it into the table has enough of design and flexibility
merits: error handling, allowing any type of dependencies of requests
by handling it in the user space, etc.

> and needs to be of
> limited scope.

And I don't think we can force it, neither with limiting exposure to
submission only nor with the Ming's group based approach. The user can
always queue a request that will never complete and/or by using
DEFER_TASKRUN and just not letting it run. In this sense it might be
dangerous to block requests of an average system shared block device,
but if it's fine with ublk it sounds like it should be fine for any of
the aforementioned approaches.

> Each request type would need to support it. For normal read/write, I'd
> suggest just adding IORING_OP_READ_LOCAL and WRITE_LOCAL to do that.

-- 
Pavel Begunkov

  parent reply	other threads:[~2024-10-31 13:25 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-10-25 12:22 [PATCH V8 0/8] io_uring: support sqe group and leased group kbuf Ming Lei
2024-10-25 12:22 ` [PATCH V8 1/7] io_uring: add io_link_req() helper Ming Lei
2024-10-25 12:22 ` [PATCH V8 2/7] io_uring: add io_submit_fail_link() helper Ming Lei
2024-10-25 12:22 ` [PATCH V8 3/7] io_uring: add helper of io_req_commit_cqe() Ming Lei
2024-10-25 12:22 ` [PATCH V8 4/7] io_uring: support SQE group Ming Lei
2024-10-29  0:12   ` Jens Axboe
2024-10-29  1:50     ` Ming Lei
2024-10-29 16:38       ` Pavel Begunkov
2024-10-25 12:22 ` [PATCH V8 5/7] io_uring: support leased group buffer with REQ_F_GROUP_KBUF Ming Lei
2024-10-29 16:47   ` Pavel Begunkov
2024-10-30  0:45     ` Ming Lei
2024-10-30  1:25       ` Pavel Begunkov
2024-10-30  2:04         ` Ming Lei
2024-10-31 13:16           ` Pavel Begunkov
2024-10-25 12:22 ` [PATCH V8 6/7] io_uring/uring_cmd: support leasing device kernel buffer to io_uring Ming Lei
2024-10-25 12:22 ` [PATCH V8 7/7] ublk: support leasing io " Ming Lei
2024-10-29 17:01 ` [PATCH V8 0/8] io_uring: support sqe group and leased group kbuf Pavel Begunkov
2024-10-29 17:04   ` Jens Axboe
2024-10-29 19:18     ` Jens Axboe
2024-10-29 20:06       ` Jens Axboe
2024-10-29 21:26         ` Jens Axboe
2024-10-30  2:03           ` Ming Lei
2024-10-30  2:43             ` Jens Axboe
2024-10-30  3:08               ` Ming Lei
2024-10-30  4:11                 ` Ming Lei
2024-10-30 13:20                   ` Jens Axboe
2024-10-31  2:53                     ` Ming Lei
2024-10-31 13:35                       ` Jens Axboe
2024-10-31 15:07                         ` Jens Axboe
2024-10-31 13:42                       ` Pavel Begunkov
2024-10-30 13:18                 ` Jens Axboe
2024-10-31 13:25               ` Pavel Begunkov [this message]
2024-10-31 14:29                 ` Jens Axboe
2024-10-31 15:25                   ` Pavel Begunkov
2024-10-31 15:42                     ` Jens Axboe
2024-10-31 16:29                       ` Pavel Begunkov

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