[petsc-users] %T (percent time in this phase)

[Barry Smith]

> On Sep 28, 2021, at 10:55 AM, Karthikeyan Chockalingam - STFC UKRI <karthikeyan.chockalingam at stfc.ac.uk> wrote:
> 
> Hello,
>  
> I ran ex45 in the KPS tutorial, which is a 3D finite-difference Poisson problem. I noticed from the output from using the flag -log_summary that for various events their respective %T (percent time in this phase) do not add up to 100 but rather exceeds 100. So, I gather there is some overlap among these events. I am primarily looking at the events KSPSetUp, KSPSolve, PCSetUp and PCSolve. Is it possible to get a mutually exclusive %T or Time for these individual events? I have attached  the log_summary output file from my run for your reference.
>  

  For nested solvers it is tricky to get the times to be mutually exclusive because some parts of the building of the preconditioner is for some preconditioners delayed until the solve has started. 

  It looks like you are using the default preconditioner options which for this example are taking more or less no time since so many iterations are needed. It is best to use -pc_type mg to use geometric multigrid on this problem.

  Barry



> Thanks!
> Karthik.
>  
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> <ksp_ex45_N511_cpu_6.txt>

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