Atlas s oftware structure
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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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Atlas s oftware structure

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


Atlas t3 virtual system design

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


Real virtual comparison designs

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


Athena performance cpu bound

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


D3pd maker performance cpu i o bound

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


Iostat from real machines when 8 parallel d3pd jobs on real virtual

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


Proof performance

Proof performance


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