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io_uring: use slist for completion batching

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Currently we collect requests for completion batching in an array.
Replace them with a singly linked list. It's as fast as arrays but
doesn't take some much space in ctx, and will be used in future patches.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/a666826f2854d17e9fb9417fb302edfeb750f425.1632516769.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2021-09-24 21:59:44 +01:00 committed by Jens Axboe
parent 5ba3c874eb
commit 6f33b0bc4e
1 changed files with 25 additions and 27 deletions
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52
fs/io_uring.c
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@ -322,8 +322,8 @@ struct io_submit_state {
/*
* Batch completion logic
*/
struct io_kiocb *compl_reqs[IO_COMPL_BATCH];
unsigned int compl_nr;
struct io_wq_work_list compl_reqs;
/* inline/task_work completion list, under ->uring_lock */
struct list_head free_list;
};
@ -882,6 +882,8 @@ struct io_kiocb {
struct io_wq_work work;
const struct cred *creds;
struct io_wq_work_node comp_list;
/* store used ubuf, so we can prevent reloading */
struct io_mapped_ubuf *imu;
};
@ -1168,7 +1170,7 @@ static inline void req_ref_get(struct io_kiocb *req)
static inline void io_submit_flush_completions(struct io_ring_ctx *ctx)
{
if (ctx->submit_state.compl_nr)
if (!wq_list_empty(&ctx->submit_state.compl_reqs))
__io_submit_flush_completions(ctx);
}
@ -1325,6 +1327,7 @@ static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
INIT_LIST_HEAD(&ctx->submit_state.free_list);
INIT_LIST_HEAD(&ctx->locked_free_list);
INIT_DELAYED_WORK(&ctx->fallback_work, io_fallback_req_func);
INIT_WQ_LIST(&ctx->submit_state.compl_reqs);
return ctx;
err:
kfree(ctx->dummy_ubuf);
@ -1826,11 +1829,16 @@ static inline bool io_req_needs_clean(struct io_kiocb *req)
static void io_req_complete_state(struct io_kiocb *req, long res,
unsigned int cflags)
{
struct io_submit_state *state;
if (io_req_needs_clean(req))
io_clean_op(req);
req->result = res;
req->compl.cflags = cflags;
req->flags |= REQ_F_COMPLETE_INLINE;
state = &req->ctx->submit_state;
wq_list_add_tail(&req->comp_list, &state->compl_reqs);
}
static inline void __io_req_complete(struct io_kiocb *req, unsigned issue_flags,
@ -2319,13 +2327,14 @@ static void io_req_free_batch(struct req_batch *rb, struct io_kiocb *req,
static void __io_submit_flush_completions(struct io_ring_ctx *ctx)
__must_hold(&ctx->uring_lock)
{
struct io_wq_work_node *node, *prev;
struct io_submit_state *state = &ctx->submit_state;
int i, nr = state->compl_nr;
struct req_batch rb;
spin_lock(&ctx->completion_lock);
for (i = 0; i < nr; i++) {
struct io_kiocb *req = state->compl_reqs[i];
wq_list_for_each(node, prev, &state->compl_reqs) {
struct io_kiocb *req = container_of(node, struct io_kiocb,
comp_list);
__io_cqring_fill_event(ctx, req->user_data, req->result,
req->compl.cflags);
@ -2335,15 +2344,18 @@ static void __io_submit_flush_completions(struct io_ring_ctx *ctx)
io_cqring_ev_posted(ctx);
io_init_req_batch(&rb);
for (i = 0; i < nr; i++) {
struct io_kiocb *req = state->compl_reqs[i];
node = state->compl_reqs.first;
do {
struct io_kiocb *req = container_of(node, struct io_kiocb,
comp_list);
node = req->comp_list.next;
if (req_ref_put_and_test(req))
io_req_free_batch(&rb, req, &ctx->submit_state);
}
} while (node);
io_req_free_batch_finish(ctx, &rb);
state->compl_nr = 0;
INIT_WQ_LIST(&state->compl_reqs);
}
/*
@ -2668,17 +2680,10 @@ static void io_req_task_complete(struct io_kiocb *req, bool *locked)
unsigned int cflags = io_put_rw_kbuf(req);
long res = req->result;
if (*locked) {
struct io_ring_ctx *ctx = req->ctx;
struct io_submit_state *state = &ctx->submit_state;
if (*locked)
io_req_complete_state(req, res, cflags);
state->compl_reqs[state->compl_nr++] = req;
if (state->compl_nr == ARRAY_SIZE(state->compl_reqs))
io_submit_flush_completions(ctx);
} else {
else
io_req_complete_post(req, res, cflags);
}
}
static void __io_complete_rw(struct io_kiocb *req, long res, long res2,
@ -6962,15 +6967,8 @@ issue_sqe:
* doesn't support non-blocking read/write attempts
*/
if (likely(!ret)) {
if (req->flags & REQ_F_COMPLETE_INLINE) {
struct io_ring_ctx *ctx = req->ctx;
struct io_submit_state *state = &ctx->submit_state;
state->compl_reqs[state->compl_nr++] = req;
if (state->compl_nr == ARRAY_SIZE(state->compl_reqs))
io_submit_flush_completions(ctx);
if (req->flags & REQ_F_COMPLETE_INLINE)
return;
}
linked_timeout = io_prep_linked_timeout(req);
if (linked_timeout)