Performance studies for ATLAS workloads in many-core Grid and HPC environments

Developments in microprocessor technology have confirmed the trend towards higher core-counts and decreased amount of memory per core, resulting in major improvements in power efficiency for a given level of performance. Core-counts have increased significantly over the past five years for the x86_64 architecture, which is dominating in the LHC computing environment, and the higher core density is not only a feature of large HPC systems, but is also readily available on commodity hardware preferentially used at Grid sites. The baseline multi-core workloads are however still largely based on 8 cores. The job are sized accordingly in terms of number of events processed. The new multi-threaded AthenaMT framework has been introduced for ATLAS data processing and simulation for Run-3 in order to address the performance limitations of the classic single-threaded Athena when run in parallel in multi-core jobs. In this work, the performance of some ATLAS workloads is investigated when scaling core-counts up to whole node where possible and at different job sizes with the aim of providing input to software developers.