The CMS muon system has played a key role for many physics results obtained
from the LHC Run-1 data. During the Long Shutdown (2013-2014) significant
upgrades have been carried out on the muon detectors and on the L1 muon
trigger. In parallel the algorithms for muon reconstruction and identification
have been improved for both the High-Level Trigger and the offline
reconstruction. Results of studies performed on data and Monte Carlo
simulations will be presented, with focus on the improvements aiming to ensure
an excellent performance in conditions of multiplicity of pileup events and
bunch spacing expected during the high-luminosity phase of Run-2. The early
muon performance results from LHC Run-2 will be shown.Comment: 8 pages, 13 figures, to be published in the proceedings of EPS-HEP
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