[Trilinos-Users] scaling with trilinos tpetra and anasazi solvers
Heroux, Michael A
maherou at sandia.gov
Thu Jan 29 05:03:34 MST 2015
Mike,
It is hard to say for sure why you are seeing the results you have. One thing you could do is write a simple MPI code that does a vector operation such as:
int localn = 50000000/size; // size is the number of MPI ranks
// define arrays x, y, w appropriately
// define ntrials so that the job runs a significant amount of time.
for (int j=0; j< ntrials; ++j)
?for (int i=0; i< localn; ++i) w[i] += alpha*x[i] + y[i];
With a tridiagonal system and the power method, your computation and data access should be similar to the above operation. This should give you some sense of what to expect.
Mike
________________________________
From: trilinos-users-bounces at software.sandia.gov <trilinos-users-bounces at software.sandia.gov> on behalf of Mike Atambo <mikeat4999 at gmail.com>
Sent: Monday, January 26, 2015 7:29 AM
To: Trilinos-Users at software.sandia.gov
Subject: [EXTERNAL] [Trilinos-Users] scaling with trilinos tpetra and anasazi solvers
My apology, i send an earlier email to an older thread, this is a correction.
Im trying to solve a system using tpetra and anasazi's krylov-shur, but there seems to
be no scaling with number of processors, i tried to run some of the examples, and
they reflect the same things i saw in my code,
attached (If list accepts attachments... hoping) is the lesson_03 power method, changed to create a tridiagonal sparse matrix,
with about 50 000 000 global indices, the run time seems the same for 2 to 16 processors,
is there something im missing?
$ time mpirun -np 2 ./powerm.x
real 3m16.014s
user 3m5.610s
sys 0m4.452s
$ time mpirun -np 8 ./powerm.x | grep real
real 3m14.229s
user 3m7.938s
sys 0m4.939s
$ time mpirun -np 16 ./powerm.x
real 3m18.153s
user 3m10.202s
sys 0m6.108s
Mike.
matambo at ictp.it<mailto:matambo at ictp.it>
Ext .139
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