Cutting across a Trig

Consider the intersection points of the curve $y=2 \sin \frac{\pi}{8}x \quad (x \geq 0)$ and the line $y=1$ . If $x_1$ , $x_2$ , $x_3$ , $\cdots$ are the $x$ -coordinates of those points in ascending order, what is the value of $x_1+x_2+x_3+x_4+x_5+x_6?$