On 6 January 2017 at 22:31, Łukasz Kasza <rpgw...@wp.pl> wrote: > > > Dear PETSc Users, > > Please consider the following 2 snippets which do exactly the same > (calculate a sum of two vectors): > 1. > VecAXPY(amg_level_x[level],1.0,amg_level_residuals[level]); > > 2. > VecGetArray(amg_level_residuals[level], &values); > VecSetValues(amg_level_x[level],size,indices,values,ADD_VALUES); > VecRestoreArray(amg_level_residuals[level], &values); > VecAssemblyBegin(amg_level_x[level]); > VecAssemblyEnd(amg_level_x[level]); > > In my program I have both of the snippets executed in a loop. The problem > with the first one is that the longer the program goes the longer it takes > to execute it. At the same time the execution time of the second snippet is > more or less constant. I don't know why but after a few hundreds of > iterations VecAXPY takes more than MatMult on the matrix and vector of the > same size and after that it still grows!
How did you profile this? > Always returning a correct value though. I am using 4.5.3 version, Which version of PETSc are you using?? Current release is 3.7.5 > the vectors are > sequential. VecAXPY in such case is just a wrapper for blas, do you have > any idea why the execution time of this function constantly grows? > Maybe your code is leaking memory and ultimately your OS starts swapping? Please send the code. Thanks, Dave > > Best regards. > > >
