about parallel execution

[Satish Balay]

Note: the porgram/code executed on each processor is the same. However
the data on each processor could be different. This ammounts to
distributing work across all processors, and noprocessor is doing
duplicate work.

[This is the meaning of single program multiple data] Sounds like you
need a good introduction to parallel computing.

Satish

On Tue, 17 Oct 2006, Yixun Liu wrote:

> Hi,
> 
> Thanks for your reply. I read the message you provide and Berend said that "So not only PETSC functions are called by each processor, every command you write will be called by each processor". However,if each PETSC function is called by each processor, the function like 
> VecSet(F_global, zero), in which F_global is a parallel vector, will be called many times. In my opinion, to be called once is enough.
> 
> Regards,
> 
> Yixun
> 
> ----- Original Message ----- 
> From: "Satish Balay" <balay at mcs.anl.gov>
> To: <petsc-users at mcs.anl.gov>
> Sent: Tuesday, October 17, 2006 10:09 PM
> Subject: Re: about parallel execution
> 
> 
> > Note: PETSc uses MPI - and it follws the SPMD [Single Program Multiple
> > Data] model. You might want to check the replies to the same question
> > posted earlier at:
> > 
> > http://www-unix.mcs.anl.gov/web-mail-archive/lists/petsc-users/2006/10/msg00052.html
> > 
> > Satish
> > 
> > On Tue, 17 Oct 2006, Hong Zhang wrote:
> > 
> >> 
> >> Yixun,
> >> 
> >> Chapter 1 of the
> >> Petsc users manual gives detailed instruction
> >> on
> >> 1. set petsc environment
> >> 2. write petsc program
> >> 3. compile and run program
> >> 
> >> You may start running petsc examples as described
> >> in the manual.
> >> 
> >> Hong
> >> 
> >> On Tue, 17 Oct 2006, Yixun Liu wrote:
> >> 
> >> > Hi,
> >> > I am a new user of PETSC. I want to know how to execute of the PETSC application.
> >> > For example, my code are like below,
> >> >
> >> > PETSCInitialize();
> >> > code1;
> >> > code2;
> >> > .....
> >> > PETSCFinalize();
> >> >
> >> > Does PETSC copy the above codes, assuming there n processors, to each processor? Will code1 be execute on each processor?
> >> >
> >> > Best regards,
> >> >
> >> > Yixun
> >> >
> >> 
> >> 
> >
> 
>