io_uring: defer flushing cached reqs
Awhile there are requests in the allocation cache -- use them, only if
those ended go for the stashed memory in comp.free_list. As list
manipulation are generally heavy and are not good for caches, flush them
all or as much as can in one go.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
[axboe: return success/failure from io_flush_cached_reqs()]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/fs/io_uring.c b/fs/io_uring.c
index bff5bc4..4a28032 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1952,25 +1952,35 @@ static inline void io_req_complete(struct io_kiocb *req, long res)
__io_req_complete(req, 0, res, 0);
}
+static bool io_flush_cached_reqs(struct io_submit_state *state)
+{
+ struct io_kiocb *req = NULL;
+
+ while (!list_empty(&state->comp.free_list)) {
+ req = list_first_entry(&state->comp.free_list, struct io_kiocb,
+ compl.list);
+ list_del(&req->compl.list);
+ state->reqs[state->free_reqs++] = req;
+ if (state->free_reqs == ARRAY_SIZE(state->reqs))
+ break;
+ }
+
+ return req != NULL;
+}
+
static struct io_kiocb *io_alloc_req(struct io_ring_ctx *ctx)
{
struct io_submit_state *state = &ctx->submit_state;
BUILD_BUG_ON(IO_REQ_ALLOC_BATCH > ARRAY_SIZE(state->reqs));
- if (!list_empty(&state->comp.free_list)) {
- struct io_kiocb *req;
-
- req = list_first_entry(&state->comp.free_list, struct io_kiocb,
- compl.list);
- list_del(&req->compl.list);
- return req;
- }
-
if (!state->free_reqs) {
gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;
int ret;
+ if (io_flush_cached_reqs(state))
+ goto got_req;
+
ret = kmem_cache_alloc_bulk(req_cachep, gfp, IO_REQ_ALLOC_BATCH,
state->reqs);
@@ -1986,7 +1996,7 @@ static struct io_kiocb *io_alloc_req(struct io_ring_ctx *ctx)
}
state->free_reqs = ret;
}
-
+got_req:
state->free_reqs--;
return state->reqs[state->free_reqs];
}
