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

On 8/14/21 1:36 PM, Pavel Begunkov wrote:

On 8/14/21 8:31 PM, Pavel Begunkov wrote:

quoted

On 8/14/21 8:13 PM, Jens Axboe wrote:

quoted

On 8/14/21 10:26 AM, Pavel Begunkov wrote:

quoted

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

quoted

quoted

@@ -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