Re: [PATCH v9 06/11] io_uring: introduce attributes for read/write and PI support

[Christoph Hellwig <hch@lst.de>]

On Mon, Nov 18, 2024 at 04:59:22PM +0000, Pavel Begunkov wrote:
>>
>> Can we please stop overdesigning the f**k out of this?  Really,
>
> Please stop it, it doesn't add weight to your argument. The design
> requirement has never changed, at least not during this patchset
> iterations.

That's what you think because you are overdesigning the hell out of
it.  And at least for me that rings every single alarm bell about
horrible interface design.

>> either we're fine using the space in the extended SQE, or
>> we're fine using a separate opcode, or if we really have to just
>> make it uring_cmd.  But stop making thing being extensible for
>> the sake of being extensible.
>
> It's asked to be extendible because there is a good chance it'll need to
> be extended, and no, I'm not suggesting anyone to implement the entire
> thing, only PI bits is fine.

Extensibility as in having reserved fields that can be checked for
is one thing.  "Extensibility" by adding indirections over indirections
without a concrete use case is another thing.  And we're deep into the
latter phase now.

> And no, it doesn't have to be "this or that" while there are other
> options suggested for consideration. And the problem with the SQE128
> option is not even about SQE128 but how it's placed inside, i.e.
> at a fixed spot.
>
> Do we have technical arguments against the direction in the last
> suggestion?

Yes.  It adds completely pointless indirections and variable offsets.
How do you expect people to actually use that sanely without
introducing bugs left right and center?

I really don't get why you want to make an I/O fast path as complicated
as possible.