Transition to a new CPU benchmark G. Merino, GDB 14 Jan 2008 on behalf of the “GDB benchmarking WG”: HEPIX: Manfred Alef, Helge Meinhard, Michelle Michelotto Experiments: Peter Hristov, Alessandro De Salvo and Franco Brasolin, Marie-Christine Sawley, Hubert Degaudenzi Chair: Gonzalo Merino

Background July 2008: The HEPIX CPU WG recommended the MB to adopt SPECall_cpp2006 as new benchmark. Document describing the new benchmark chosen and the conditions in which it will have to be run is in preparation by the HEPIX WG. Mandate of our Working Group: Publish the recipe for running the benchmark (see above) Agree on conversion factors to convert experiment requirement and site pledges tables from si2k units to the new units Aim of this talk is not to present a formal proposal, but to report on the Group discussions up to now and get reactions/feedback.

LXBENCH cluster at CERN Cluster with 8 reference machines for benchmarking at CERN: lxbench01, lxbench02, … lxbench08 (see https://twiki.cern.ch/twiki/bin/view/FIOgroup/TsiLxbench) Old (SPECint2000) and new (SPECall_cpp2006) benchmarks have been run in every machine. Experiments also ran their apps in every machine (May-08, HEPIX CPU WG) Conclusion: All 4 experiments see good correlation between their applications and both benchmarks. NOTE: Not all the experiments ran in lxbench08 Only ATLAS managed to run and provide results for lxbench08 LHCb says it did run, but results still not provided to the HEPIX group CMS and ALICE did not manage to run in lxbench08 in May

SPECs on LXBENCH SPECall_cpp2006 (new) KSI2K-LCG (old) Ratio new/old Intel Xeon 2.8 GHz lxbench01 10,24 2,25 4,55 lxbench02 9,63 2,24 4,29 AMD Opteron 275 lxbench03 28,03 6,20 4,52 Intel Xeon 5150 lxbench04 35,58 8,51 4,18 Intel Xeon 5160 lxbench05 38,21 9,27 4,12 AMD Opteron 2218 lxbench06 31,67 6,85 4,62 Intel Xeon E5345 lxbench07 57,52 14,19 4,05 Intel Xeon E5410 lxbench08 60,76 15,83 3,84

Current processors at the T0/T1s Result of a poll the Tier-0 and Tier-1s showing a snapshot of the number of cores currently installed of each processor type Xeon E5345 (Quad-core) Xeon E5430 AMD Intel Dual-Core Quad-Core

Transition to a new CPU unit The most representative platform, providing the majority of capacity at T0/T1s today are the Intel QuadCore processors. Propose to focus on the conversion factor results got at the newest (Intel QuadCore) machines: lxbench07 and lxbench08 lxbench07: 4,05 lxbench08: 3,84 Manfred Alef did the exercise of computing the CPU performance delivered by the whole GridKa farm with both the old and the new SPEC benchmarks large site with quite a lot of different processors  realistic “mixture” Result: new/old conversion factor = 4,19 Precision O(5%) intrinsic to these measurements: not significative.

Transition to a new CPU unit Proposal: Take a simple approach and adopt 4,00 as conversion factor.  Give more importance to having a simple rule for the transition period than discussing about decimals within the 5% precision. Caveat: during the next days, ALICE and CMS will complete their benchmarking runs up to lxbench08 to confirm the good correlation (no surprises expected). Transition period: before end April (Spring C-RRB meeting) Experiments will re-compute requirements tables given the new LHC schedule: new numbers should be computed already with the new unit. Sites should buy SPECcpu2006 and calibrate their farms to report their current CPU power in the new unit. Pledges for the Spring CRRB should be expressed in the new unit.