Re: [PATCH 1/5] io_uring: optimise iowq refcounting

[Jens Axboe <axboe@kernel.dk>]

On 8/14/21 1:36 PM, Pavel Begunkov wrote:
> On 8/14/21 8:31 PM, Pavel Begunkov wrote:
>> On 8/14/21 8:13 PM, Jens Axboe wrote:
>>> On 8/14/21 10:26 AM, Pavel Begunkov wrote:
>>>> If a requests is forwarded into io-wq, there is a good chance it hasn't
>>>> been refcounted yet and we can save one req_ref_get() by setting the
>>>> refcount number to the right value directly.
>>>
>>> Not sure this really matters, but can't hurt either. But...
>>
>> The refcount patches made this one atomic worse, and I just prefer
>> to not regress, even if slightly
>>
>>>> @@ -1115,14 +1115,19 @@ static inline void req_ref_get(struct io_kiocb *req)
>>>>  	atomic_inc(&req->refs);
>>>>  }
>>>>  
>>>> -static inline void io_req_refcount(struct io_kiocb *req)
>>>> +static inline void __io_req_refcount(struct io_kiocb *req, int nr)
>>>>  {
>>>>  	if (!(req->flags & REQ_F_REFCOUNT)) {
>>>>  		req->flags |= REQ_F_REFCOUNT;
>>>> -		atomic_set(&req->refs, 1);
>>>> +		atomic_set(&req->refs, nr);
>>>>  	}
>>>>  }
>>>>  
>>>> +static inline void io_req_refcount(struct io_kiocb *req)
>>>> +{
>>>> +	__io_req_refcount(req, 1);
>>>> +}
>>>> +
>>>
>>> I really think these should be io_req_set_refcount() or something like
>>> that, making it clear that we're actively setting/manipulating the ref
>>> count.
>>
>> Agree. A separate patch, maybe?
> 
> I mean it just would be a bit easier for me, instead of rebasing
> this series and not yet sent patches.

I think it should come before this series at least, or be folded into the
first patch. So probably no way around the rebase, sorry...
-- 
Jens Axboe