* [LIBURING] Check cq ring overflow status
@ 2020-07-07 13:25 Xiaoguang Wang
0 siblings, 0 replies; only message in thread
From: Xiaoguang Wang @ 2020-07-07 13:25 UTC (permalink / raw)
To: io-uring; +Cc: axboe, joseph.qi, Xiaoguang Wang
If cq ring has been overflowed, need to enter kernel to flush cqes.
Signed-off-by: Xiaoguang Wang <[email protected]>
---
src/include/liburing.h | 1 +
src/include/liburing/io_uring.h | 2 +-
src/queue.c | 22 +++++++++++++++++-----
src/setup.c | 2 ++
4 files changed, 21 insertions(+), 6 deletions(-)
diff --git a/src/include/liburing.h b/src/include/liburing.h
index 0505a4f..9f7df1f 100644
--- a/src/include/liburing.h
+++ b/src/include/liburing.h
@@ -46,6 +46,7 @@ struct io_uring_cq {
unsigned *kring_entries;
unsigned *kflags;
unsigned *koverflow;
+ unsigned *kcheck_overflow;
struct io_uring_cqe *cqes;
size_t ring_sz;
diff --git a/src/include/liburing/io_uring.h b/src/include/liburing/io_uring.h
index 6a73522..15e273b 100644
--- a/src/include/liburing/io_uring.h
+++ b/src/include/liburing/io_uring.h
@@ -211,7 +211,7 @@ struct io_cqring_offsets {
__u32 overflow;
__u32 cqes;
__u32 flags;
- __u32 resv1;
+ __u32 check_overflow;
__u64 resv2;
};
diff --git a/src/queue.c b/src/queue.c
index 88e0294..36f00bf 100644
--- a/src/queue.c
+++ b/src/queue.c
@@ -32,6 +32,14 @@ static inline bool sq_ring_needs_enter(struct io_uring *ring,
return false;
}
+static inline bool cq_ring_needs_flush(struct io_uring *ring)
+{
+ if (!ring->cq.kcheck_overflow)
+ return false;
+
+ return IO_URING_READ_ONCE(*ring->cq.kcheck_overflow);
+}
+
static int __io_uring_peek_cqe(struct io_uring *ring,
struct io_uring_cqe **cqe_ptr)
{
@@ -68,21 +76,25 @@ int __io_uring_get_cqe(struct io_uring *ring, struct io_uring_cqe **cqe_ptr,
do {
unsigned flags = 0;
+ bool cq_overflow_flush = false;
err = __io_uring_peek_cqe(ring, &cqe);
if (err)
break;
- if (!cqe && !to_wait && !submit) {
- err = -EAGAIN;
- break;
+ if (!cqe) {
+ cq_overflow_flush = cq_ring_needs_flush(ring);
+ if (!to_wait && !submit && !cq_overflow_flush) {
+ err = -EAGAIN;
+ break;
+ }
}
if (wait_nr && cqe)
wait_nr--;
- if (wait_nr)
+ if (wait_nr || cq_overflow_flush)
flags = IORING_ENTER_GETEVENTS;
if (submit)
sq_ring_needs_enter(ring, submit, &flags);
- if (wait_nr || submit)
+ if (wait_nr || submit || cq_overflow_flush)
ret = __sys_io_uring_enter(ring->ring_fd, submit,
wait_nr, flags, sigmask);
if (ret < 0) {
diff --git a/src/setup.c b/src/setup.c
index 860c112..1a03cc3 100644
--- a/src/setup.c
+++ b/src/setup.c
@@ -78,6 +78,8 @@ err:
cq->cqes = cq->ring_ptr + p->cq_off.cqes;
if (p->cq_off.flags)
cq->kflags = cq->ring_ptr + p->cq_off.flags;
+ if (p->cq_off.check_overflow)
+ cq->kcheck_overflow = cq->ring_ptr + p->cq_off.check_overflow;
return 0;
}
--
2.17.2
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