High-performance multi-user code development with Google Code  Current status  (...just google for Pencil Code)

Pencil code Started in Sept with Wolfgang Dobler High order (6 th order in space, 3 rd order in time) Cache & memory efficient MPI, can run PacxMPI (across countries!) Maintained/developed by ~40 people (SVN) Automatic validation (over night or any time)  s/pt/step at , 2048 procs Isotropic turbulence –MHD, passive scl, CR Stratified layers –Convection, radiation Shearing box –MRI, dust, interstellar –Self-gravity Sphere embedded in box –Fully convective stars –geodynamo Other applications –Chemistry, combustion –Spherical coordinates

Scaling properties 3 Wlad Lyra on KrakenBabkovskaia et al (2011)

Pencil Code Started in Sept with Wolfgang Dobler High order (6 th order in space, 3 rd order in time) Cache & memory efficient MPI, can run PacxMPI (across countries!) Maintained/developed by ~40 people (SVN) Automatic validation (over night or any time) Max resolution so far , 4096 procs Isotropic turbulence –MHD, passive scl, CR Stratified layers –Convection, radiation Shearing box –MRI, dust, interstellar –Self-gravity Sphere embedded in box –Fully convective stars –geodynamo Other applications –Homochirality –Spherical coordinates

5 Google Code webpage

6 Continuous updates online

7 Automatic validation tests

8 Evolution of code size User meetings: 2005 Copenhagen 2006 Copenhagen 2007 Stockholm 2008 Leiden 2009 Heidelberg 2010 New York 2011 Toulouse 2012 Helsinki

9 Increase in # of auto tests

10 Regularity of check-ins

11 More check-ins since 2010

12 Return to previous rate

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17 Tutorial

18 Tutorial pages

19 Olhol

20 Olhoh.net analysis

21 Credit

22 Free licence, but giving credit to research

23 Faster and bigger machines

processor run at

25 Hyperviscous, Smagorinsky, normal Inertial range unaffected by artificial diffusion Haugen & Brandenburg (PRE, astro-ph/ ) height of bottleneck increased onset of bottleneck at same position

26 Online data reduction and visualization non-helically forced turbulence

27 Scalars on periphery of the box

28 MRI turbulence MRI = magnetorotational instability w/o hypervisc. t = 600 = 20 orbits w/o hypervisc.  t = 60 = 2 orbits

29 Vorticity and Density See poster by Tobi Heinemann on density wave excitation!

30 Transfer equation & parallelization Analytic Solution: Ray direction Intrinsic Calculation Processors

31 The Transfer Equation & Parallelization Analytic Solution: Ray direction Communication Processors

32 The Transfer Equation & Parallelization Analytic Solution: Ray direction Processors Intrinsic Calculation

33 Future developments Adaptive/multiple mesh More 3-D online graphics output Poisson solver for non-Cartesian geometries Parallel developments with graphics card