Calibrating QCD MC models to the early LHC data

In this talk we review the MC tunes used in QCD studies at ATLAS. Starting from the models used to generate distributions for the ATLAS Physics TDR, the speaker has shown how the different tunes evolved as new data measurements and new models became available. The latest ATLAS tune to the underlying event was also presented. The speaker has also proposed a debate on strategies for re-calibrating the MC event generators using the early date measured not only by ATLAS but also by the other major LHC experiments.