[petsc-users] Optimized Option

[zhenglun.wei at gmail.com]

Thanks for your reply.
So, if I want to use '--with-debugging=0', what is the PETSC_ARCH equal to?
I just tried to use PETSC = arch-opt, and a error message comes up:
~/petsc-dev/conf/variables:95: ~/petsc-dev/arch-opt/conf/petscvariables: No  
such file or directory
~l/petsc-dev/conf/rules:1018: ~/petsc-dev/arch-opt/conf/petscrules: No such  
file or directory
make: *** No rule to make target `~l/petsc-dev/arch-opt/conf/petscrules'.  
Stop.
this really confused me.

thanks,
Alan

On , Barry Smith <bsmith at mcs.anl.gov> wrote:


> On Jun 3, 2011, at 2:57 PM, Alan Wei wrote:



> > Dear Sir/Madam,

> > Lately, I read there is a optimized version of PETSc by  
> using '--with-debugging=0'. I have two questions here:

> > 1, Do I need to use '/config/configure.py ... --with-debugging=0' when  
> I configure the PETSc in order to use the non-debugging version of PETSc?  
> Therefore, if I want to switch PETSc between these two versions, I have  
> to keep configuring.





> ABSOLUTELY NOT. You use two different values of the environmental  
> variable PETSC_ARCH and switch back and forth by changing the variable.  
> You can even change it on the make command line. For example make mycode  
> PETSC_ARCH=arch-opt



> Note that you can use any name you want for the values of PETSC_ARCH. I  
> often use arch-debug and arch-opt to keep track of them.





> > 2, I was using the '--with-debugging=0' to configure the PETSc.  
> However, I tested the computational rate by executing the ex29.c. The  
> non-debugging version does not improve the speed much; in the contrary,  
> it slow down the speed a little bit. The comparison is attached here. Any  
> idea on this.



> It depends on the compiler and particular code you are running. We  
> recommend using the option -log_summary to see how much time is spent in  
> each part of the computation and how much it gets better with  
> optimization.





> Barry





> >

> > thanks in advance,

> > Alan

> >

> >




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