Hi Erik,
We evolve alpha and beta for the gauge variables as given in equations
7a and 7b of http://arxiv.org/pdf/1506.06153.pdf. The number I reported
for LazEv was using 5th order dissipation applied to all 21 evolved
variables (alp, beta^i, At_{ij}, gt_{ij}, Gammat^{i}, trK, and xi).
LazEv is calculating the Hamiltonian and Momentum constraints as well as
the constraints on Gammat^i using 4th order stencils.
I also forgot to mention that I did these tests on 16 nodes, and the
memory usage was relatively low ( ~2 GB/MPI process ).
I will give the internal dissipation for McLachlan a try.
Thanks,
Jim
On 07/27/2015 05:56 PM, Erik Schnetter wrote:
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 <[email protected]
<mailto:[email protected]>> 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 <http://13.0.2.146> 6)
cluster 8) impi/4.1.0.030 <http://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 <[email protected] <mailto:[email protected]>>
http://www.perimeterinstitute.ca/personal/eschnetter/
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