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

[Pavel Begunkov <asml.silence@gmail.com>]

On 11/19/24 12:49, Christoph Hellwig wrote:
> On Mon, Nov 18, 2024 at 05:45:02PM +0000, Pavel Begunkov wrote:
>> Exactly, _fast path_. PI-only handling is very simple, I don't buy
>> that "complicated". If we'd need to add more without an API expecting
>> that, that'll mean a yet another forest of never ending checks in the
>> fast path effecting all users.
> 
> Well, that's a good argument for a separate opcode for PI, or at least

No, it's not. Apart from full duplication I haven't seen any PI
implementation that doesn't add overhead to the io_uring read-write
path, which is ok, but pretending that dropping a new opcode solves
everything is ill advised.

And I hope there is no misunderstanding on the fact that there are
other criteria as well, and what's not explicitly mentioned is usually
common sense. For example, it's supposed to be correct and bug free
as well as maintainable.

> for a 128-byte write, isn't it?  I have real hard time trying to find
> a coherent line in your arguments.

When coming from invalid assumptions everything would seem incoherent.
And please, I'm not here to humour you, you can leave your crude
statements for yourself, it's getting old.

-- 
Pavel Begunkov