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Atlas S oftware Structure

Atlas S oftware Structure. Complicated system maintained at CERN Framework for Monte Carlo and real data ( A thena) MC data generation, simulation and reconstruction Analysis of MC/real data CPU bound Conversion of data files (D3PD maker) Raw data (AOD/ESD) → flat ntuples ( rootuples )

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Atlas S oftware Structure

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  1. Atlas Software Structure • Complicated system maintained at CERN • Framework for Monte Carlo and real data (Athena) • MC data generation, simulation and reconstruction • Analysis of MC/real data • CPU bound • Conversion of data files (D3PD maker) • Raw data (AOD/ESD) → flat ntuples (rootuples) • Extreme I/O • Analysis of ntuples (root/proof) • I/O bound+CPU combination Compare these programs in Real and Virtual Systems

  2. Atlas T3 Virtual System design Dell blade server (openfiler) storage File server VM master WAN /LAN USERS VM VM VM VM Switch atlasgw User Desktops 12 Condor manager/ scheduler Proof master Proxy for cvmfs / coolDB iSCSI Switch VM VM VM VM VM VM SUSE corei7 SUSE corei7 VM 40+ VMs Batch nodes Batch 3GB memory/VM, no user login

  3. Real/Virtual Comparison designs Dell PowerEdge R710 Dell PowerEdge R710 SUSE 11.1 /Xen kernel 16 cernvm (v1.6 Xen batch SL4) 2GB memory per VM Athena with CVMFS Local File system Bonnie++ disk benchmarks(inside VM) SL5 8 core HT real Machine 36GB memory total Athena locally installed Local File system Bonnie++ disk benchmarks Read PerChr: 67955K/s Read Block: 270546K/s Random seeks: 428.9/sec Read PerChr: 55828K/s Read Block: 252955K/s Random seeks: 410/sec

  4. Athena Performance - CPU Bound • For CPU bound jobs: 10% performance loss for virtual systems • MC generation/simulation/reconstruction is CPU bound • Performance scales with CPU speed HT Athena 15.3.1.6, full MC, 1000 events

  5. D3PD Maker Performance - CPU+I/O Bound • No I/O performance loss for virtual machines with ATLAS software • Evidence for I/O performance (D3PD Maker) in virtual machines being better than in real machines (up to 20%) due to other limitations • Local HD raid array with 250 MB/s read bandwidth (block) and 440 random seeks/sec can’t provide enough I/O,  Performance peaks at 6 jobs; performance loss noticeable at 3 jobs relative to Virtual RAM disk. Egamma D3PD Maker, 1000 events HT *All memory caches cleared before each run

  6. iostat from real machines when 8 parallel D3PD jobs on real/virtual

  7. Proof performance

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