[CIG-SHORT] elapsed time concerns

alberto cominelli alberto.cominelli at gmail.com
Mon Nov 21 14:20:38 PST 2016


Thank you so much Brad.
i will try tomorrow.
I wonder if you suggestions do apply aslo for a skewed cartesian grid..
Acualy my grid is skwed to follow a sloping fault, hence cell cross section
paralle to y is not a square. I am attaching a pdf to show a (poor) view of
the grid and some vtlk files to explain better my geometry.
regards,
Alberto.


2016-11-21 21:58 GMT+01:00 Brad Aagaard <baagaard at usgs.gov>:

> Alberto,
>
> The log shows that the Setup Stage is mostly spent in "ElIm init", which
> is ElasticityImplicit.initialize(). This is most likely associated with
> setting the initial stresses using a SimpleDB object.
>
> The SimpleGridDB provides much faster interpolation than
> SimpleDB for a logically Cartesian grid because it can find the relevant
> points without a global search. The points need to conform to a grid, but
> the x, y, and z coordinates do not have to be spaced uniformly.
>
> See Appendix C.3 of the manual for an example of the SimpleGridDB.
>
> Regards,
> Brad
>
>
> On 11/21/2016 12:34 PM, alberto cominelli wrote:
>
>> Brad,
>> I have included also my cfg files..
>> regards,
>> Alberto.
>>
>> 2016-11-21 19:49 GMT+01:00 Brad Aagaard <baagaard at usgs.gov
>> <mailto:baagaard at usgs.gov>>:
>>
>>     Alberto,
>>
>>     Please send the entire output of the PETSc log (everything after
>>     "PETSc Performance Summary") for a representative simulation. It is
>>     usually easiest to simply send the entire output of stdout (gzip it
>>     if necessary to reduce size). The individual event logging provides
>>     more specifics than the summary of stages. We add custom events in
>>     the PETSc logging for many of the PyLith routines.
>>
>>     If you need help understanding the format of the summary, then see
>>     the Profiling chapter of the PETSc manual:
>>     http://www.mcs.anl.gov/petsc/petsc-current/docs/manual.pdf
>>     <http://www.mcs.anl.gov/petsc/petsc-current/docs/manual.pdf>.
>>
>>
>>     Regards,
>>     Brad
>>
>>
>>
>>
>>
>>     On 11/19/2016 08:09 AM, alberto cominelli wrote:
>>
>>         Brad,
>>         I followed you suggestion and I also modified a bit the code to
>>         track
>>         the time spent in integrator:
>>
>>               start_time = time.time()
>>               integrator.initialize(totalTime, numTimeSteps, normalizer)
>>               str = "--- %s seconds in integrator.initialize ---" %
>>         (time.time()
>>         - start_time)
>>               self._info.log(str)
>>          (import time at the beginning
>>         of lib64/python2.7/site-packages/pylith/problems/Formulation.py )
>>         The I run a simple case with 5733 nodes/ 4800 elements  and
>> pylith
>>         spent  37 seconds to run with 26.5418641567 seconds in
>>         integrator.initialize.
>>         If I look at Petsc  log at the end I get this:
>>         Summary of Stages:   ----- Time ------  ----- Flops -----  ---
>>         Messages
>>         ---  -- Message Lengths --  -- Reductions --
>>                                 Avg     %Total     Avg     %Total   counts
>>         %Total     Avg         %Total   counts   %Total
>>          0:      Main Stage: 1.3829e-01   0.4%  0.0000e+00   0.0%
>> 0.000e+00
>>         0.0%  0.000e+00        0.0%  0.000e+00   0.0%
>>          1:         Meshing: 1.5950e-01   0.4%  1.7262e+04   0.0%
>> 0.000e+00
>>         0.0%  3.874e-02        0.0%  8.000e+00 100.0%
>>          2:           Setup: 2.7486e+01  77.3%  2.7133e+07   0.2%
>> 8.000e+00
>>         1.9%  2.181e+01        0.0%  0.000e+00   0.0%
>>          3: Reform Jacobian: 2.8208e-01   0.8%  4.1906e+08   3.5%
>> 0.000e+00
>>         0.0%  0.000e+00        0.0%  0.000e+00   0.0%
>>          4: Reform Residual: 9.8572e-02   0.3%  6.1111e+07   0.5%
>> 8.000e+00
>>         1.9%  1.967e+03        3.1%  0.000e+00   0.0%
>>          5:           Solve: 5.5077e+00  15.5%  1.1537e+10  95.1%
>> 3.970e+02
>>          96.1%  6.197e+04       96.9%  0.000e+00   0.0%
>>          6:         Prestep: 5.7586e-02   0.2%  0.0000e+00   0.0%
>> 0.000e+00
>>         0.0%  0.000e+00        0.0%  0.000e+00   0.0%
>>          7:            Step: 8.9577e-02   0.3%  0.0000e+00   0.0%
>> 0.000e+00
>>         0.0%  0.000e+00        0.0%  0.000e+00   0.0%
>>          8:        Poststep: 1.6417e+00   4.6%  8.2252e+07   0.7%
>> 0.000e+00
>>         0.0%  0.000e+00        0.0%  0.000e+00   0.0%
>>          9:        Finalize: 7.7139e-02   0.2%  0.0000e+00   0.0%
>> 0.000e+00
>>         0.0%  0.000e+00        0.0%  0.000e+00   0.0%
>>
>>         As far as I understand 27 seconds are spent in setup, which I
>>         suppose
>>         includes integrators.
>>         I simplified the problem using a linear interpolation between
>>         two points
>>         to define the initial stress state but still setup phase takes
>>         80% of
>>         the time.
>>         Is it fine this timing?
>>         I may send you my cfg files if you like,
>>         Regards,
>>           Alberto.
>>
>>         P.S: I noticed that Petsc log makes my little modification into
>>         python
>>         scripts useless..I will remove.
>>
>>
>>         2016-11-19 0:04 GMT+01:00 Brad Aagaard <baagaard at usgs.gov
>>         <mailto:baagaard at usgs.gov>
>>         <mailto:baagaard at usgs.gov <mailto:baagaard at usgs.gov>>>:
>>
>>
>>
>>             Alberto,
>>
>>             The PETSc log summary provides important performance
>>         information.
>>
>>             Use these settings to see what is happening in the solver
>>         and the
>>             performance (as used in examples/3d/hex8/pylithapp.cfg):
>>
>>
>>             [pylithapp.petsc]
>>             ksp_monitor = true
>>             ksp_view = true
>>             snes_monitor = true
>>             snes_view = true
>>             log_view = true
>>
>>             Regards,
>>             Brad
>>
>>
>>
>>             On 11/18/16 2:24 PM, alberto cominelli wrote:
>>
>>                 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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