Re: [PATCH] io_uring: kill io_cqring_ev_posted() and __io_cq_unlock_post()

[Jens Axboe <axboe@kernel.dk>]

On 11/24/22 12:17?PM, Pavel Begunkov wrote:
> On 11/24/22 18:46, Jens Axboe wrote:
>> On 11/24/22 9:16?AM, Pavel Begunkov wrote:
>>> On 11/21/22 14:52, Jens Axboe wrote:
>>>> __io_cq_unlock_post() is identical to io_cq_unlock_post(), and
>>>> io_cqring_ev_posted() has a single caller so migth as well just inline
>>>> it there.
>>>
>>> It was there for one purpose, to inline it in the hottest path,
>>> i.e. __io_submit_flush_completions(). I'll be reverting it back
>>
>> The compiler is most certainly already doing that, in fact even
> 
> .L1493:
> # io_uring/io_uring.c:631:???? io_cq_unlock_post(ctx);
> ????movq??? %r15, %rdi??? # ctx,
> ????call??? io_cq_unlock_post??? #

Doubled checked here, and you're actually right:

    55bc:       94000000        bl      4760 <io_cq_unlock_post>                

Huh, that's very odd that it doesn't inline it. It doesn't even it I
mark it inline, __always_inline gets it done.

> Even more, after IORING_SETUP_CQE32 was added I didn't see
> once __io_fill_cqe_req actually inlined even though it's marked
> so.

Doesn't seem to be inlined here either. Compiler:

gcc (Debian 12.2.0-9) 12.2.0

>> __io_submit_flush_completions() is inlined in
>> io_submit_flush_completions() for me here.
> 
> And io_submit_flush_completions is inlined as well, right?
> That would be quite odd, __io_submit_flush_completions() is not
> small by any means and there are 3 call sites.

io_submit_flush_completions() doesn't get inlined,
__io_submit_flush_completions() gets inlined in
io_submit_flush_completions().

-- 
Jens Axboe