hi,
On 9/22/21 1:34 PM, Xiaoguang Wang wrote:
For an echo-server based on io_uring's IORING_POLL_ADD_MULTI feature,
only poll request are completed in task work, normal read/write
requests are issued when user app sees cqes on corresponding poll
requests, and they will mostly read/write data successfully, which
don't need task work. So at least for echo-server model, batching
poll request completion properly will give benefits.
Currently don't find any appropriate place to store batched poll
requests, put them in struct io_submit_state temporarily, which I
think it'll need rework in future.
Signed-off-by: Xiaoguang Wang <xiaoguang.wang@xxxxxxxxxxxxxxxxx>
---
fs/io_uring.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 63 insertions(+), 1 deletion(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 6fdfb688cf91..14118388bfc6 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -321,6 +321,11 @@ struct io_submit_state {
*/
struct io_kiocb *compl_reqs[IO_COMPL_BATCH];
unsigned int compl_nr;
+
+ struct io_kiocb *poll_compl_reqs[IO_COMPL_BATCH];
+ bool poll_req_status[IO_COMPL_BATCH];
+ unsigned int poll_compl_nr;
+
/* inline/task_work completion list, under ->uring_lock */
struct list_head free_list;
@@ -2093,6 +2098,8 @@ static void ctx_flush_and_put(struct io_ring_ctx *ctx, bool *locked)
percpu_ref_put(&ctx->refs);
}
+static void io_poll_flush_completions(struct io_ring_ctx *ctx, bool *locked);
+
static void tctx_task_work(struct callback_head *cb)
{
bool locked = false;
@@ -2103,8 +2110,11 @@ static void tctx_task_work(struct callback_head *cb)
while (1) {
struct io_wq_work_node *node;
- if (!tctx->task_list.first && locked && ctx->submit_state.compl_nr)
+ if (!tctx->task_list.first && locked && (ctx->submit_state.compl_nr ||
+ ctx->submit_state.poll_compl_nr)) {
io_submit_flush_completions() shouldn't be called if there are no requests... And the
check is already inside for-next, will be
if (... && locked) {
io_submit_flush_completions();
if (poll_compl_nr)
io_poll_flush_completions();
OK, thanks for pointing this, and I have dropped the poll request
completion batching patch, since
it shows performance fluctuations, hard to say whether it's useful.
Regards,
Xiaoguang Wang
}
io_submit_flush_completions(ctx);
+ io_poll_flush_completions(ctx, &locked);
+ }
spin_lock_irq(&tctx->task_lock);
node = tctx->task_list.first;
@@ -5134,6 +5144,49 @@ static inline bool io_poll_complete(struct io_kiocb *req, __poll_t mask)
static bool __io_poll_remove_one(struct io_kiocb *req,
struct io_poll_iocb *poll, bool do_cancel);
+static void io_poll_flush_completions(struct io_ring_ctx *ctx, bool *locked)
+ __must_hold(&ctx->uring_lock)
+{
+ struct io_submit_state *state = &ctx->submit_state;
+ struct io_kiocb *req, *nxt;
+ int i, nr = state->poll_compl_nr;
+ bool done, skip_done = true;
+
+ spin_lock(&ctx->completion_lock);
+ for (i = 0; i < nr; i++) {
+ req = state->poll_compl_reqs[i];
+ done = __io_poll_complete(req, req->result);
I believe we first need to fix all the poll problems and lay out something more intuitive
than the current implementation, or it'd be pure hell to do afterwards.
Can be a nice addition, curious about numbers as well.
