[petsc-users] EPSSolve in a loop

[Jed Brown]

Dharmendar Reddy <dharmareddy84 at gmail.com> writes:

> There is no CHKMEMQ statements. 

I meant inside the VecScale() implementation.  It turns out that
PetscStackCall(), which is used around all BLAS/Lapack functions, among
others, currently includes CHKMEMQ.

CHKMEMQ walks all allocations to check for memory corruption.  It can be
rather time consuming when many objects (or other small allocations)
occur.  If you run with '-malloc 0', the performance problem will go
away.  When PETSc is configured --with-debugging=0, CHKMEMQ does nothing
unless you pass '-malloc' (so it'll be fast by default in optimized
mode).

petsc-dev, is this performance degradation of multiple orders of
magnitude really tolerable?  Should we turn off malloc checking around
BLAS/Lapack functions unless the user passes an extra flag (but leave
sentinel checking around user functions because that's where almost all
the memory bugs are)?