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Software Optimization

Profiling

Documentation for profiling can be found herer: https://twiki.cern.ch/twiki/bin/view/LHCb/CodeAnalysisTools

Benchmarking

Information on HEPSPEC06

Running the DIRAC Benchmark

Use cases

In AFS

Scripts as representative as possible of the various LHCb computing phases are gathered in AFS in:

/afs/cern.ch/lhcb/group/profiling/UseCases/

In the bin directories the following files are present:

  • runTestReconstruction.sh
  • runTestSimulation.sh
  • runTestStripping.sh
The number of events to process can be passed as argument.


Local installation of Reconstruction

Copy the files:

/afs/cern.ch/lhcb/group/profiling/UseCases/Reconstruction/

To your target host.

Then define an env variable called MYSITEROOT, where the software will be installed (several gigs needed).

Doing the following will install the soft and setup the environment:

export MYSITEROOT=`pwd`
export CMTCONFIG=x86_64-slc5-gcc46-opt
sh install_Reco14.sh
. setenv_Reco14.sh

then you can run with:

sh run_Reco14.sh

Ben

Other test cases are possible, the following presentation shows how to run the HLT algorithms in Brunel for easier tests.

Optimization ideas and results

Here is an (unordered) list of tracks/ideas that could be investigated to see if they can help improve the performance of the LHCb software,in term of both CPU and memory usage

  • Compiler autovectorization (gcc 4.7, icc)
  • Link Time optimization (usable as gcc 4.7)
  • C++ 11 (possibly removes some memory copies)
  • Use of Compiler intrisics to add CPU specific optimizations
  • CPU PMU counters analysis (especiallyLast Level Cache misses) and memory usage optimization
  • mx32 test
  • Test of zram (compressed memory) to limit memory usage
  • kvm usage

Analysis performed

Tools

Code Analysis Tools

Using Markus's TES Tracer

Detailed Histogram Timing

Use of igprof

References

c.f. References

RunningMoore

-- BenjaminCouturier - 20-Jun-2012

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Topic revision: r13 - 2013-02-01 - StefanLohn
 
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