[Users] McLachlan help

[Erik Schnetter]

Jim

Thanks for posting the details.

Can you give us more details about the LazEv scheme? In particular there
may be differences in the gauge. What (gauge) variables do you evolve? What
gauge conditions do you use? And what kind of dissipation do you apply? Can
you point us to the source code?

For the new McLachlan, you would probably use the built-in dissipation
instead of thorn Dissipation, which should lead to a small speed-up.

-erik

On Mon, Jul 27, 2015 at 4:43 PM, James Healy <jchsma at rit.edu> wrote:

> Hello,
>
> I have been running some tests on Stampede comparing the run speed of
> McLachlan to RIT's evolution thorn LazEv.  I started with the
> qc0-mclachlan.par parameter file included with the Einstein Toolkit, added
> a few refinement levels, increased the resolution and changed McLachlan to
> be 8th order (and increased the number of ghost zones to 5).  I also
> increased the initial separation so the finest grids aren't already
> overlapping.  To compare with LazEv, I removed the McLachlan and
> Dissipation thorns and replaced them with LazEv. Everything else in the
> parameter file is exactly the same.  I tried using both the McLachlan
> master and rewrite branches.
>
> The grid setup is 10 levels of refinement, dx=4M on the coarsest with
> outer boundary at 400M, M/128 on the finest with r=0.6M, CFL is 0.25.  Both
> use 8th order spatial differencing with ghost_size=5 and 5th order
> dissipation.
>
> Below is a summary of the results as reported at iteration 256 from
> Carpet::physical_time_per_hour:
>
> McLachlan - rewrite branch: 3.0596110 M/hr
> McLachlan - master branch: 3.8033607 M/hr
> LazEv - 4.1941544 M/hr
>
> I am using the stampede-impi.cfg configuration file in simfactory. "module
> list" returns:
>
>   1) TACC-paths   3) cluster-paths      5) xalt/0.4.6   7) TACC
>   2) Linux        4) intel/13.0.2.146   6) cluster      8) impi/4.1.0.030
>
> Attached is my parameter file.  I pasted the McLachlan parameters below.
> Are there any optimizations that I can use for McLachlan? Are the
> parameters I am using for it what would be used for production runs?
>
> ML_BSSN::harmonicN           = 1      # 1+log
> ML_BSSN::harmonicF           = 2.0    # 1+log
> ML_BSSN::ShiftGammaCoeff     = 0.75
> ML_BSSN::BetaDriver          = 1.0
> ML_BSSN::LapseAdvectionCoeff = 1.0
> ML_BSSN::ShiftAdvectionCoeff = 1.0
>
> ML_BSSN::MinimumLapse        = 1.0e-8
>
> ML_BSSN::my_initial_boundary_condition = "extrapolate-gammas"
> ML_BSSN::my_rhs_boundary_condition     = "NewRad"
> Boundary::radpower                     = 2
>
> ML_BSSN::ML_log_confac_bound = "none"
> ML_BSSN::ML_metric_bound     = "none"
> ML_BSSN::ML_Gamma_bound      = "none"
> ML_BSSN::ML_trace_curv_bound = "none"
> ML_BSSN::ML_curv_bound       = "none"
> ML_BSSN::ML_lapse_bound      = "none"
> ML_BSSN::ML_dtlapse_bound    = "none"
> ML_BSSN::ML_shift_bound      = "none"
> ML_BSSN::ML_dtshift_bound    = "none"
>
> ML_BSSN::fdOrder = 8
>
> ActiveThorns = "Dissipation"
>
> Dissipation::order = 5
> Dissipation::vars  = "
>         ML_BSSN::ML_metric
>         ML_BSSN::ML_trace_curv
>         ML_BSSN::ML_curv
>         ML_BSSN::ML_Gamma
>         ML_BSSN::ML_lapse
>         ML_BSSN::ML_shift
>         ML_BSSN::ML_dtlapse
>         ML_BSSN::ML_dtshift
> "
>
> ActiveThorns = "ML_ADMConstraints"
>
>
> Thanks,
> Jim Healy
>
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-- 
Erik Schnetter <schnetter at cct.lsu.edu>
http://www.perimeterinstitute.ca/personal/eschnetter/
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