[petsc-users] Obtaining compiling and building information from a.out

[TAY wee-beng]

Hi,

I emailed as shown below a while ago but I have yet to get a response. 
Can someone help?

Thank you very much.

Yours sincerely,

================================================
TAY Wee-Beng (Zheng Weiming) 郑伟明
Personal research webpage: http://tayweebeng.wixsite.com/website
Youtube research showcase: https://www.youtube.com/channel/UC72ZHtvQNMpNs2uRTSToiLA
linkedin: www.linkedin.com/in/tay-weebeng
================================================

On 29/3/2018 1:48 PM, TAY wee-beng wrote:
>
> On 28/3/2018 5:45 PM, Matthew Knepley wrote:
>> On Tue, Mar 27, 2018 at 10:17 PM, TAY wee-beng <zonexo at gmail.com 
>> <mailto:zonexo at gmail.com>> wrote:
>>
>>     Hi Dave,
>>
>>     I looked at the output using log_view and re-compile. However,
>>     although I use the same options "-xHost -g -O3 -openmp" (some
>>     filenames and dir names are now different but they are actually
>>     the same), I still get different results timing. I have attach
>>     both, fast and slow. So what else can I do to pinpoint the
>>     differences?
>>
>> The solver options must be different. In Fast, there is almost no 
>> time in LUFactor, but in Slow its half the time.
>>
>>    Matt
> Hi Matt,
>
> Finally found that it was because I was using KSPRICHARDSON in the new 
> code. KSPGMRES in the old code is much faster.
>
> I also tried cg, lsqr, fgmres. CG and GMRES seem similar in term of 
> best performance. Are there any other recommendations to try? The 
> Poisson eqn is symmetric.
>
> I also tried -pc_type mg -pc_mg_nlevels 2 instead of -poisson_pc_type 
> gamg -poisson_pc_gamg_agg_nsmooths 1.
>
> It reduces the runtime from 2.25 to 1.46min.
>
> However, I found that my subroutine is very similar to my momentum 
> subroutine, which is based on KSPSolve:
>
> 0. DMDACreate, DMDACreate3d etc
> 1. Assemble matrix
> 2. KSPSetOperators, KSPSetType etc
> 3. KSPSolve
>
> However, the 2D Poisson example in ex5f.F90 uses SNESSetDM, SNESSolve 
> etc. So does it matter if I use SNESSolve or KSPSolve if I'm using 
> -pc_type mg?
>
>>     Thank you very much.
>>
>>     Yours sincerely,
>>
>>     ================================================
>>     TAY Wee-Beng (Zheng Weiming) 郑伟明
>>     Personal research webpage:http://tayweebeng.wixsite.com/website
>>     <http://tayweebeng.wixsite.com/website>
>>     Youtube research showcase:https://www.youtube.com/channel/UC72ZHtvQNMpNs2uRTSToiLA
>>     <https://www.youtube.com/channel/UC72ZHtvQNMpNs2uRTSToiLA>
>>     linkedin:www.linkedin.com/in/tay-weebeng
>>     <http://www.linkedin.com/in/tay-weebeng>
>>     ================================================
>>
>>     On 27/3/2018 5:22 PM, Dave May wrote:
>>>
>>>
>>>     On 27 March 2018 at 10:16, TAY wee-beng <zonexo at gmail.com
>>>     <mailto:zonexo at gmail.com>> wrote:
>>>
>>>         Hi,
>>>
>>>         I have been compiling and building different version of my
>>>         CFD with the intel 2016, 2018 compilers, and also different
>>>         compiling options.
>>>
>>>         I tested a version of my a.out and it is much faster than
>>>         the other a.out, using only 3 min instead of more than 10min
>>>         to solve a certain case using GAMG.
>>>
>>>         However, I can't recall how it was compiled. I only know
>>>         that I used the intel 2016 compiler.
>>>
>>>         So is there any way I can find out how the a.out was
>>>         compiled? Like what options were used?
>>>
>>>
>>>     Since you posted to the list I presume "a.out" links against
>>>     petsc...
>>>     If so, run your code with
>>>       -log_view
>>>
>>>     Upon calling PetscFinalize(), you will get all the options given
>>>     to PETSc configure, plus the CFLAGS, link lines, etc.
>>>
>>
>>
>>
>>
>> -- 
>> What most experimenters take for granted before they begin their 
>> experiments is infinitely more interesting than any results to which 
>> their experiments lead.
>> -- Norbert Wiener
>>
>> https://www.cse.buffalo.edu/~knepley/ <http://www.caam.rice.edu/%7Emk51/>
>

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