  A precision measurement of the LHC luminosity is a key ingredient for its
physics program. In this contribution first of all we review the theoretical
accuracy in the computation of LHC benchmark processes. Then we discuss the
impact of available and future LHC data in global analysis of parton
distributions, with emphasis on the treatment of normalization uncertainties.
Finally we present some suggestions for the physics opportunities that can
become available by measuring ratios of cross sections between the 8 TeV and 7
TeV runs.
