[PATCH ncns v1 4/4] chnet: ring: Only notify CQE free slot when it's available

[Ammar Faizi <ammarfaizi2@gnuweeb.org>]

In `CNRingCtx::WaitCQE`, we don't actually always need to call
`NotifyWaitCQEFreeSlot()`. To reduce the call overhead, just check
whether the CQE slot is available or not. If it's available, then call
it, otherwise, just don't.

Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
---
 chnet/chnet_ring.cc | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/chnet/chnet_ring.cc b/chnet/chnet_ring.cc
index e9d0d57..5c6c14c 100644
--- a/chnet/chnet_ring.cc
+++ b/chnet/chnet_ring.cc
@@ -375,10 +375,12 @@ void CNRingCtx::WaitCQE(uint32_t to_wait)
 	if (to_wait > max_to_wait)
 		to_wait = max_to_wait;
 
-	NotifyWaitCQEFreeSlot();
-
 	std::unique_lock<std::mutex> cqe_lock(state_->cqe_lock_);
 	cq_size = cqe_size();
+
+	if (cq_size < cq_mask + 1)
+		NotifyWaitCQEFreeSlot();
+
 	if (to_wait <= cq_size)
 		return;
 
-- 
Ammar Faizi