Re: [PATCH 2/3] io_uring/poll: flag request as having gone through poll wake machinery

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

On 7/14/25 15:54, Jens Axboe wrote:
> On 7/14/25 3:26 AM, Pavel Begunkov wrote:
>> On 7/12/25 21:59, Jens Axboe wrote:
>>> On 7/12/25 5:39 AM, Pavel Begunkov wrote:
>>>> On 7/12/25 00:59, Jens Axboe wrote:
>>>>> No functional changes in this patch, just in preparation for being able
...>>>> Same, it's overhead for all polled requests for a not clear gain.
>>>> Just move it to the arming function. It's also not correct to
>>>> keep it here, if that's what you care about.
>>>
>>> Not too worried about overhead, for an unlocked or. The whole poll
>>
>> You know, I wrote this machinery and optimised it, I'm not saying it
>> to just piss you off, I still need it to work well for zcrx :)
> 
> This was not a critique of the code, it's just a generic statement on
> the serialization around poll triggering is obviously a lot more
> expensive than basic flag checking or setting. Every comment is not a
> backhanded attack on someones code.

Not taken this way, it works well enough for such highly concurrent
synchronisation.

>> Not going into details, but it's not such a simple unlocked or. And
>> death by a thousand is never old either.
> 
> That's obviously true, I was just trying to set expectations that a
> single flag mask is not really a big deal. If the idea and feature was
> fully solidified and useful, then arguing that adding a bit or is a
> problem is nonsense.

Quite the opppsite, it should be argued about, and not because "or"
is expensive, but because it's a write in a nuanced place.

  By that standard, we could never add anything to
> the code, only remove. At the same time, adding frivolous code is of
> course always a bad idea.

-- 
Pavel Begunkov