ATLAS TDAQ System Performance in 2012 Data Taking

The ATLAS Trigger and Data Acquisition (TDAQ) system is responsible for the selection and the conveyance of physics data, reducing the rate of stored events from the initial 40 MHz LHC frequency to several hundreds Hz. The TDAQ system is organised in a three-level selection scheme, including a hardware-based first-level trigger and second- and third-level triggers implemented as software systems distributed on commodity hardware nodes. In this poster, we report on the experience of operating the system in the challenging environment of the 2012 LHC proton-proton run.