GMRES performance

[jarunan at ascomp.ch]

Hello,

I would like to know some information about GMRES performance in PETSc  
if you have any experience.

I am running a parallel test case(9300 cells) comparing cpu time using  
by solvers in Petsc. While BICGSTAB was doing 0.9 sec, GMRES 15 sec  
with the same preconditioner(Additive Schwarz). I did not expect that  
GMRES would be that much slower. Everything is default.

Please share your experiences, how the performance of solvers are in  
your test cases. Which option I should set to improve GMRES  
performance? Is there the best combination of Preconditioner and solver?

Thank you very much
Jarunan

-- 
Jarunan Panyasantisuk
Development Engineer
ASCOMP GmbH, Technoparkstr. 1
CH-8005 Zurich, Switzerland
Phone : +41 44 445 4072
Fax   : +41 44 445 4075
E-mail: jarunan at ascomp.ch
www.ascomp.ch