On 8/14/21 1:31 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
Not really against it, but doubt it's measurable if you end up hitting
the io-wq slower path anyway. But as I said, can't really hurt, so not
aginst it.
>>> @@ -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?
Maybe just fold it into this one, as it's splitting out a helper anyway.
Or do it as a prep patch before this one, up to you.
--
Jens Axboe
