On 2/9/21 5:03 PM, Pavel Begunkov wrote:
> 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@xxxxxxxxx>
> ---
> fs/io_uring.c | 29 +++++++++++++++++++----------
> 1 file changed, 19 insertions(+), 10 deletions(-)
>
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 64d3f3e2e93d..17194e0d62ff 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -1953,25 +1953,34 @@ static inline void io_req_complete(struct io_kiocb *req, long res)
> __io_req_complete(req, 0, res, 0);
> }
>
> +static void io_flush_cached_reqs(struct io_submit_state *state)
> +{
> + do {
> + struct io_kiocb *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;
> + } while (!list_empty(&state->comp.free_list));
> +}
> +
> 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 (!list_empty(&state->comp.free_list)) {
> + io_flush_cached_reqs(state);
> + goto out;
> + }
I think that'd be cleaner as:
if (io_flush_cached_reqs(state))
goto got_req;
and have io_flush_cached_reqs() return true/false depending on what it did.
--
Jens Axboe
