  Hosting six different experiments at four different interaction points and
widely different requirements for the running conditions, the LHC machine has
been faced with a long list of challenges in the first three years of
luminosity production (2010-2012, Run 1), many of which were potentially
capable of limiting the performance due to instabilities resulting from the
extremely high bunch brightness. Nonetheless, LHC met the challenges and
performed extremely well at high efficiency and routinely with beam brightness
at twice the design, well over one-third of the time in collision for physics,
average luminosity lifetimes in excess of 10 h and extremely good background
conditions in the experiments. While the experimental running configurations
remain largely the same for the future high luminosity proton-proton
operational mode, the energy and the luminosity should increase significantly,
making a prior assessment of related beam-beam effects extremely important to
guarantee high performance. Of particular interest is the need for levelling
the luminosity individually in the different experiments. Luminosity control as
the more general version of 'levelling' has been at the heart of the success
for LHCb, and to a large extent also for ALICE, throughout Run 1. With the
increasing energy and potential luminosity, luminosity control may be required
by all the experiments at some point in the future as a means of controlling
the pileup conditions and trigger rates, but possibly also as a way of
optimizing the integrated luminosity. This paper reviews the various
motivations and possibilities for controlling the luminosity from the
experiments' point of view, and outlines the future running conditions and
desiderata for the experiments as they are viewed currently, with the aim of
giving guidelines for different options.
