Performance of the ATLAS Trigger and DAQ systems at the LHC with p-p collisions at $sqrt{s}=7$TeV

The ATLAS trigger system is responsible for reducing the event rate, from the design bunch-crossing rate of 40 MHz, to an average recording rate of 200 Hz, by selecting signal-like events out of the extremely large background. The ATLAS trigger is designed in three levels. The first-level (L1) is implemented in custom-built electronics, the two levels of the high level trigger (HLT) are software triggers executed on large computing farms. The first-level trigger is comprised of calorimeter, muon and forward triggers to identify event features, such as missing transverse energy, as well as candidate electrons, photons, jets and muons. In this talk an overview of the performance of the Trigger and Data Acquisition system during 2011 data taking is shown.