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From: Jens Axboe <axboe@kernel.dk>
To: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: linux-fsdevel@vger.kernel.org, linux-aio@kvack.org,
	linux-block@vger.kernel.org, linux-arch@vger.kernel.org,
	hch@lst.de, jmoyer@redhat.com, avi@scylladb.com
Subject: Re: [PATCH 05/15] Add io_uring IO interface
Date: Sun, 13 Jan 2019 09:22:16 -0700
Message-ID: <54976aac-bef2-880f-dc10-e3030189a08a@kernel.dk> (raw)
In-Reply-To: <f97a5b9f-68f3-c4af-649d-7dffbc35e37f@kernel.dk>

On 1/11/19 11:34 AM, Jens Axboe wrote:
> On 1/11/19 11:19 AM, Martin K. Petersen wrote:
>>
>> Jens,
>>
>>> +struct io_uring_sqe {
>>> +	__u8	opcode;
>>> +	__u8	flags;
>>> +	__u16	ioprio;
>>> +	__s32	fd;
>>> +	__u64	off;
>>> +	union {
>>> +		void	*addr;
>>> +		__u64	__pad;
>>> +	};
>>> +	__u32	len;
>>> +	union {
>>> +		__kernel_rwf_t	rw_flags;
>>> +		__u32		__resv;
>>> +	};
>>> +};
>>
>> A bit tongue in cheek and yet somewhat serious: While I'm super excited
>> about the 4 x 64 bitness of the sqe, where does the integrity buffer go?
>> Or the 128-bit KV store key. How do we extend this interface beyond the
>> flags?
> 
> For integrity buffers, how about we stash them on the side? The newer
> series has an extra system call, io_uring_register(), which is currently
> used for registering files and buffers for IO on the side. You could
> trivially tie an integrity buffer to an sqe through that.
> 
> For KV, I thint that's an actually interesting use case (sorry,
> integrity), and we might just want to bite the bullet and extend the sqe
> to full 64 bytes.  We're currently at 48 bytes, which leaves us with 16
> bytes of space for KV, and other use cases.

I bit the bullet and bumped the size. 64 bytes is a nicer size in terms
of cachelines anyway, and I really doubt that 48 vs 64 bytes makes a
size consumption problem for anyone.

The buf_index is only used for the fixed buffers, which means that we have
16 bytes / 128 bits that we can grab for things like KV.

-- 
Jens Axboe


  reply index

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-10  2:43 [PATCHSET v2] " Jens Axboe
2019-01-10  2:43 ` [PATCH 01/15] fs: add an iopoll method to struct file_operations Jens Axboe
2019-01-10  2:43 ` [PATCH 02/15] block: wire up block device iopoll method Jens Axboe
2019-01-10  2:43 ` [PATCH 03/15] block: add bio_set_polled() helper Jens Axboe
2019-01-10  2:43 ` [PATCH 04/15] iomap: wire up the iopoll method Jens Axboe
2019-01-10  2:43 ` [PATCH 05/15] Add io_uring IO interface Jens Axboe
2019-01-11 18:19   ` Martin K. Petersen
2019-01-11 18:34     ` Jens Axboe
2019-01-13 16:22       ` Jens Axboe [this message]
2019-01-15 17:31         ` Martin K. Petersen
2019-01-10  2:43 ` [PATCH 06/15] io_uring: support for IO polling Jens Axboe
2019-01-10  2:43 ` [PATCH 07/15] io_uring: add submission side request cache Jens Axboe
2019-01-10  2:43 ` [PATCH 08/15] fs: add fget_many() and fput_many() Jens Axboe
2019-01-10  2:43 ` [PATCH 09/15] io_uring: use fget/fput_many() for file references Jens Axboe
2019-01-10  2:43 ` [PATCH 10/15] io_uring: batch io_kiocb allocation Jens Axboe
2019-01-10  2:44 ` [PATCH 11/15] block: implement bio helper to add iter bvec pages to bio Jens Axboe
2019-01-10  2:44 ` [PATCH 12/15] io_uring: add support for pre-mapped user IO buffers Jens Axboe
2019-01-10  2:44 ` [PATCH 13/15] io_uring: support kernel side submission Jens Axboe
2019-01-10  2:44 ` [PATCH 14/15] io_uring: add submission polling Jens Axboe
2019-01-10  2:44 ` [PATCH 15/15] io_uring: add io_uring_event cache hit information Jens Axboe
2019-01-10 23:12   ` Jeff Moyer
2019-01-10 23:47     ` Jens Axboe
2019-01-11  9:46 ` [PATCHSET v2] io_uring IO interface Roman Penyaev
2019-01-11 16:11   ` Ilya Dryomov
2019-01-11 16:21     ` Christoph Hellwig
2019-01-11 16:39     ` Roman Penyaev
2019-01-11 18:05   ` Jens Axboe
2019-01-16 17:49 [PATCHSET v5] " Jens Axboe
2019-01-16 17:49 ` [PATCH 05/15] Add " Jens Axboe
2019-01-17 12:02   ` Roman Penyaev
2019-01-17 13:54     ` Jens Axboe
2019-01-17 14:34       ` Roman Penyaev
2019-01-17 14:54         ` Jens Axboe
2019-01-17 15:19           ` Roman Penyaev
2019-01-17 12:48   ` Roman Penyaev
2019-01-17 14:01     ` Jens Axboe
2019-01-17 20:03       ` Jeff Moyer
2019-01-17 20:09         ` Jens Axboe
2019-01-17 20:14           ` Jens Axboe
2019-01-17 20:50             ` Jeff Moyer
2019-01-17 20:53               ` Jens Axboe
2019-01-17 21:02                 ` Jeff Moyer
2019-01-17 21:17                   ` Jens Axboe
2019-01-17 21:21                     ` Jeff Moyer
2019-01-17 21:27                       ` Jens Axboe
2019-01-18  8:23               ` Roman Penyaev

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