there are many small reasons justifying this change.
1. busy poll must be performed even on rings that have no iopoll and no
new sqe. It is quite possible that a ring configured for inbound
traffic with multishot be several hours without receiving new request
submissions
2. NAPI busy poll does not perform any credential validation
3. If the thread is awaken by task work, processing the task work is
prioritary over NAPI busy loop. This is why a second loop has been
created after the io_sq_tw() call instead of doing the busy loop in
__io_sq_thread() outside its credential acquisition block.
Signed-off-by: Olivier Langlois <olivier@xxxxxxxxxxxxxx>
---
io_uring/sqpoll.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/io_uring/sqpoll.c b/io_uring/sqpoll.c
index 3b50dc9586d1..f9964eb03803 100644
--- a/io_uring/sqpoll.c
+++ b/io_uring/sqpoll.c
@@ -195,9 +195,6 @@ static int __io_sq_thread(struct io_ring_ctx *ctx, bool cap_entries)
ret = io_submit_sqes(ctx, to_submit);
mutex_unlock(&ctx->uring_lock);
- if (io_napi(ctx))
- ret += io_napi_sqpoll_busy_poll(ctx);
-
if (to_submit && wq_has_sleeper(&ctx->sqo_sq_wait))
wake_up(&ctx->sqo_sq_wait);
if (creds)
@@ -322,6 +319,10 @@ static int io_sq_thread(void *data)
if (io_sq_tw(&retry_list, IORING_TW_CAP_ENTRIES_VALUE))
sqt_spin = true;
+ list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)
+ if (io_napi(ctx))
+ io_napi_sqpoll_busy_poll(ctx);
+
if (sqt_spin || !time_after(jiffies, timeout)) {
if (sqt_spin) {
io_sq_update_worktime(sqd, &start);
--
2.46.0
