Computing at LHC experiments in the first year of data taking at 7 TeV

After many years of development, testing and validation, the computing systems of the four LHC experiments are now in operation. The Grid computing infrastructure has been heavily utilized by ALICE, ATLAS, CMS and LHCb in the first year of LHC proton-proton collisions data taking at 7 TeV as well as in the first heavy-ion run in 2010 with remarkable success in all major workflows. The general experience of the four experiments in building and running their computing systems is presented and discussed. Highlights will be given to performances, lessons learned and expected evolutions.