[CIG-SHORT] elapsed time concerns

[alberto cominelli]

Dear All,

I am using pylith to make a convergence study on a 12 core Xeon box, with
Intel(R) Xeon(R)  E5-2643 v2 cpus running at @ 3.50GHz and 64 gb of memory.
The problem at hand is a 3D domain consisting of two layers, the upper one
dry, with 25000kg/m3 density and the lower on water saturated with a 20%
porosity.  Besides differences in saturated condistions, rock is
characterised as an elastic, istropic and homogeneous material.
The domain is discretised  by means of  hexaedral elements using a tartan
type grid developed around a fault, a 20% sloping fault. Fault rehology is
very simple, a friction model with 0.6 friction coefficient,

To simulate a consolidation problem, fluid pressure is included in the
model using initial stress on a cell basis assuming that pressure is
constant inside each cell.
This means I input a initial_stress.spatialdb file containg data for ncells
* 8 quadrature points.
I am a bit surprised by elapsed time values I get along my convergence
study.
For instance, one case consists of 52731 nodes and 48630 elements. To
properly initialise the model I give initial stress values in 386880. I
make two steps in 48 minutes, with most of the time spent in integrators -
as far as I understand.

With "Integrators" I mean what is labelled by these lines in pylith output:
-- Initializing integrators.
 >>
/home/comi/Pylith2.1.3/lib64/python2.7/site-packages/pylith/problems/Formulation.py
[0m:474 [0m:_initialize [0m
I guess this step means building residuals and stiffness matrices, but I am
not sure about. Notably, in the second steo I do not change anything and
then I get very few  linear/non linear iteration in the latter step.

I wonder if this time is fine according to you experience and if it is
worth going parallel to improve computational efficiency. I am willing to
make much more complx cases  up to some millions of nodes and I wonder how
far I can go using only one core.
Regards,
 Alberto.

I am attaching a snapshot of one simulation log (not for the entire case)
in case it may help.
Regards,
  Alberto.
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