From: Pavel Begunkov <asml.silence@gmail.com>
To: Bijan Mottahedeh <bijan.mottahedeh@oracle.com>,
axboe@kernel.dk, io-uring@vger.kernel.org
Subject: Re: [PATCH v3 08/13] io_uring: implement fixed buffers registration similar to fixed files
Date: Wed, 6 Jan 2021 22:22:57 +0000 [thread overview]
Message-ID: <2be9eefb-4353-9951-f6b6-fbd1d9735ae8@gmail.com> (raw)
In-Reply-To: <c982a4ea-e39f-d8e0-1fc7-27086395ea9a@oracle.com>
On 06/01/2021 19:46, Bijan Mottahedeh wrote:
> On 1/4/2021 6:43 PM, Pavel Begunkov wrote:
>> On 18/12/2020 18:07, Bijan Mottahedeh wrote:
>>> Apply fixed_rsrc functionality for fixed buffers support.
>>
>> git generated a pretty messy diff...
>
> I had tried to break this up a few ways but it didn't work well because I think most of the code changes depend on the io_uring structure changes. I can look again or if you some idea of how you want to split it, I can do that.
Nah, that's fine, I just may have missed something
without applying it.
>
>> Because it's do quiesce, fixed read/write access buffers from asynchronous
>> contexts without synchronisation. That won't work anymore, so
>>
>> 1. either we save it in advance, that would require extra req_async
>> allocation for linked fixed rw
>>
>> 2. or synchronise whenever async. But that would mean that a request
>> may get and do IO on two different buffers, that's rotten.
>>
>> 3. do mixed -- lazy, but if do IO then alloc.
>>
>> 3.5 also "synchronise" there would mean uring_lock, that's not welcome,
>> but we can probably do rcu.
>
> Are you referring to a case where a fixed buffer request can be submitted from async context while those buffers are being unregistered, or something like that?
Yes, io_import_fixed() called from io-wq, and in parallel with
unregister/etc. That may happen in many cases, e.g. linked reqs
or IOSQE_ASYNC.
--
Pavel Begunkov
next prev parent reply other threads:[~2021-01-06 22:27 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-18 18:07 [PATCH v3 00/13] io_uring: buffer registration enhancements Bijan Mottahedeh
2020-12-18 18:07 ` [PATCH v3 01/13] io_uring: modularize io_sqe_buffer_register Bijan Mottahedeh
2021-01-04 21:54 ` Pavel Begunkov
2021-01-06 19:46 ` Bijan Mottahedeh
2020-12-18 18:07 ` [PATCH v3 02/13] io_uring: modularize io_sqe_buffers_register Bijan Mottahedeh
2021-01-04 21:48 ` Pavel Begunkov
2020-12-18 18:07 ` [PATCH v3 03/13] io_uring: rename file related variables to rsrc Bijan Mottahedeh
2021-01-05 1:53 ` Pavel Begunkov
2021-01-06 19:46 ` Bijan Mottahedeh
2020-12-18 18:07 ` [PATCH v3 04/13] io_uring: generalize io_queue_rsrc_removal Bijan Mottahedeh
2020-12-18 18:07 ` [PATCH v3 05/13] io_uring: separate ref_list from fixed_rsrc_data Bijan Mottahedeh
2020-12-18 18:07 ` [PATCH v3 06/13] io_uring: generalize fixed_file_ref_node functionality Bijan Mottahedeh
2020-12-18 18:07 ` [PATCH v3 07/13] io_uring: add rsrc_ref locking routines Bijan Mottahedeh
2020-12-18 18:07 ` [PATCH v3 08/13] io_uring: implement fixed buffers registration similar to fixed files Bijan Mottahedeh
2021-01-05 2:43 ` Pavel Begunkov
2021-01-06 19:46 ` Bijan Mottahedeh
2021-01-06 22:22 ` Pavel Begunkov [this message]
2021-01-07 2:37 ` Pavel Begunkov
2021-01-07 21:21 ` Bijan Mottahedeh
2021-01-07 21:37 ` Pavel Begunkov
2021-01-07 22:14 ` Bijan Mottahedeh
2021-01-07 22:33 ` Pavel Begunkov
2021-01-07 23:10 ` Pavel Begunkov
2021-01-08 1:53 ` Bijan Mottahedeh
2021-01-11 5:12 ` Pavel Begunkov
2021-01-08 0:17 ` Bijan Mottahedeh
2020-12-18 18:07 ` [PATCH v3 09/13] io_uring: create common fixed_rsrc_ref_node handling routines Bijan Mottahedeh
2020-12-18 18:07 ` [PATCH v3 10/13] io_uring: generalize files_update functionlity to rsrc_update Bijan Mottahedeh
2020-12-18 18:07 ` [PATCH v3 11/13] io_uring: support buffer registration updates Bijan Mottahedeh
2020-12-18 18:07 ` [PATCH v3 12/13] io_uring: create common fixed_rsrc_data allocation routines Bijan Mottahedeh
2020-12-18 18:07 ` [PATCH v3 13/13] io_uring: support buffer registration sharing Bijan Mottahedeh
2021-01-04 17:09 ` [PATCH v3 00/13] io_uring: buffer registration enhancements Bijan Mottahedeh
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