New measurements for the mentioned, increased latency if you lock pages physically. As you can see, the violet line (without memory locking) reflect a superior latency behavior (lesser is better).
On the other side, there is one negative peek with mlockall() - but it shouldn't. After all: mlockall() prevent worst case scenario - the principal task for real-time application. On the other hand, it introduces a small overhead - but why? More kernel studies needed!