What is the synchronization cost of calling a synchronized method from a synchronized method?

Question

Is there any difference in performance between this

synchronized void x() {
    y();
}

synchronized void y() {
}

and this

Answer 1

No difference will be there. Since threads content only to acquire lock at x(). Thread that acquired lock at x() can acquire lock at y() without any contention(Because that is only thread that can reach that point at one particular time). So placing synchronized over there has no effect.