OK, I see 10us difference in a udp ping pong latency test between the case where ethtool sets interrupt moderation to (10,16) vs (10,1) $ ethtool -C ib1 adaptive-rx on rx-usecs 10 rx-frames 16 --> 9us $ ethtool -C ib1 adaptive-rx on rx-usecs 10 rx-frames 1 --> 19us Or.