H. Meinhard

A comparison of HEP code with SPEC1 benchmarks on multi-core worker nodes

The SPEC[1] CINT benchmark has been used as a performance reference for computing in the HEP community for the past 20 years. The SPECint_base2000 (SI2K) unit of performance has been used by the major HEP experiments both in the Computing Technical Design Report for the LHC experiments and in the evaluation of the Computing Centres. At recent HEPiX[3] meetings several HEP sites have reported disagreements between actual machine performances and the scores reported by SPEC. Our group performed a detailed comparison of Simulation and Reconstruction code performances from the four LHC experiments in order to find a successor to the SI2K benchmark. We analyzed the new benchmarks from SPEC CPU2006 suite, both integer and floating point, in order to find the best agreement with the HEP code behaviour, with particular attention paid to reproducing the actual environment of HEP farm i.e., each job running independently on each core, and matching compiler, optimization, percentage of integer and floating point operations, and ease of use.

Virtualization, clouds and IaaS at CERN

The four detectors at CERNs Large Hadron Collider (LHC) are delivering about 22 Petabytes of data per year. CERN-ITs computer center is part of the Worldwide LHC Computing Grid (WLCG), serving as the Tier-0 facility for processing these data. Trying to keep track with the increasing demands, CERN-IT is facing a number of challenges: more capacity needs to be provided without matching person-power; the additional capacity will be provided in a remote (more than 1000 km away from CERN) location; a more flexible and dynamic approach to meet user requests is needed; the existing scheme does not provide optimum efficiency. In order to address these challenges, CERN-IT has launched the Agile Infrastructure project. It includes better-adapted means of managing the fabric and full exploitation of virtualization and provisioning of services via internal clouds and IaaS based on the OpenStack toolkit.