[petsc-dev] Discussion about time-dependent optimization moved from PR

[Stefano Zampini]

attached the patch for ts ex2.c to reproduce the problem.
It runs 30 times the same TSSolve with a TS that has a RHSJacobian and
BEULER as a solver.
This are the times for each solve on my workstation

[szampini at localhost tutorials]$ ./ex2
0.164751
0.1406
0.148703
0.158375
0.169456
0.172364
0.179924
0.186967
0.195149
0.202559
0.214942
0.217264
0.225801
0.232413
0.240205
0.249077
0.256062
0.262738
0.270429
0.277631
0.285879
0.292678
0.299828
0.307717
0.315533
0.323094
0.330388
0.338611
0.345624
0.35268

You can see that timings (for the same exact solve) increase. If I comment
out DMCoarsenHookAdd in SNESSetUpMatrices

[szampini at localhost tutorials]$ git diff
/home/szampini/src/petsc/src/snes/interface/
diff --git a/src/snes/interface/snes.c b/src/snes/interface/snes.c
index d366a2cc69..cdb7571869 100644
--- a/src/snes/interface/snes.c
+++ b/src/snes/interface/snes.c
@@ -642,7 +642,7 @@ PetscErrorCode SNESSetUpMatrices(SNES snes)
     KSP ksp;
     ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
     ierr =
KSPSetComputeOperators(ksp,KSPComputeOperators_SNES,snes);CHKERRQ(ierr);
-    ierr =
DMCoarsenHookAdd(snes->dm,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,snes);CHKERRQ(ierr);
+    //ierr =
DMCoarsenHookAdd(snes->dm,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,snes);CHKERRQ(ierr);
   }
   PetscFunctionReturn(0);
 }

this is what I get, constant timings as expected

[szampini at localhost tutorials]$ ./ex2
0.154417
0.125632
0.125743
0.126303
0.125648
0.125593
0.125647
0.125656
0.125705
0.125705
0.125737
0.125648
0.125592
0.125568
0.125578
0.125678
0.125628
0.126056
0.125725
0.127705
0.126028
0.125671
0.125675
0.125662
0.125688
0.125767
0.12574
0.125604
0.125568
0.1256
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