[PATCH 7/8] io_uring: submit-completion free batching

Pavel Begunkov
2021-01-25T12:12:39Z

io_submit_flush_completions() does completion batching, but may also use
free batching as iopoll does. The main beneficiaries should be buffered
reads/writes and send/recv.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
fs/io_uring.c | 49 +++++++++++++++++++++++++++++--------------------
1 file changed, 29 insertions(+), 20 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index fcd8df43b6bf..7a720995e24f 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1898,26 +1898,6 @@ static void io_req_complete_nostate(struct io_kiocb *req, long res,
io_put_req(req);
}

-static void io_submit_flush_completions(struct io_comp_state *cs,
- struct io_ring_ctx *ctx)
-{
- int i, nr = cs->nr;
-
- spin_lock_irq(&ctx->completion_lock);
- for (i = 0; i < nr; i++) {
- struct io_kiocb *req = cs->reqs[i];
-
- __io_cqring_fill_event(req, req->result, req->compl.cflags);
- }
- io_commit_cqring(ctx);
- spin_unlock_irq(&ctx->completion_lock);
-
- io_cqring_ev_posted(ctx);
- for (i = 0; i < nr; i++)
- io_double_put_req(cs->reqs[i]);
- cs->nr = 0;
-}
-
static void io_req_complete_state(struct io_kiocb *req, long res,
unsigned int cflags, struct io_comp_state *cs)
{
@@ -2303,6 +2283,35 @@ static void io_req_free_batch(struct req_batch *rb, struct io_kiocb *req)
__io_req_free_batch_flush(req->ctx, rb);
}

+static void io_submit_flush_completions(struct io_comp_state *cs,
+ struct io_ring_ctx *ctx)
+{
+ int i, nr = cs->nr;
+ struct io_kiocb *req;
+ struct req_batch rb;
+
+ io_init_req_batch(&rb);
+ spin_lock_irq(&ctx->completion_lock);
+ for (i = 0; i < nr; i++) {
+ req = cs->reqs[i];
+ __io_cqring_fill_event(req, req->result, req->compl.cflags);
+ }
+ io_commit_cqring(ctx);
+ spin_unlock_irq(&ctx->completion_lock);
+
+ io_cqring_ev_posted(ctx);
+ for (i = 0; i < nr; i++) {
+ req = cs->reqs[i];
+
+ /* submission and completion refs */
+ if (refcount_sub_and_test(2, &req->refs))
+ io_req_free_batch(&rb, req);
+ }
+
+ io_req_free_batch_finish(ctx, &rb);
+ cs->nr = 0;
+}
+
/*
* Drop reference to request, return next in chain (if there is one) if this
* was the last reference to this request.
--
2.24.0