[petsc-dev] [petsc-users] EPSSolve in a loop

[Matthew Knepley]

On Sat, May 4, 2013 at 6:40 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:

> 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)?
>

I was for eliminating these before.

   Matt

-- 
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
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20130504/723d583f/attachment.html>