Acoustic liners are perforated plates with a honeycomb core, and they are the state-of-the-art method for noise attenuation over aircraft engines. They cover the inside of engine nacelles and they are effective at reducing noise, however, they increase aerodynamic drag because they behave similarly to surface roughness. We have used the compressible flow solver STREAmS and exploited the computational power of graphics processing units to perform unprecedented direct numerical simulation (DNS) a turbulent boundary layer over a realistic acoustic liner geometry. This high-Reynolds-number simulation has been performed using a mesh with over 10 Billion points, and it represents a breakthrough in the study of these surfaces. The accuracy and fidelity provided by this dataset is unsurpassed, and the insight provided by DNS will help us to devise guidelines for improving the aerodynamic penalty of acoustic liners.