[Trilinos-Users] [EXTERNAL] Re: scaling with trilinos tpetra and anasazi solvers
Heroux, Michael A
maherou at sandia.gov
Fri Jan 30 08:12:03 MST 2015
?Excellent. That is what these sanity checks are for. I am glad it worked!
________________________________
From: Mike Atambo <mikeat4999 at gmail.com>
Sent: Friday, January 30, 2015 9:06 AM
To: Heroux, Mike
Cc: Heroux, Michael A; Trilinos-Users at software.sandia.gov
Subject: [EXTERNAL] Re: [Trilinos-Users] scaling with trilinos tpetra and anasazi solvers
Mike (Heroux),
I have had a look at the code you suggested, and it led me to find a problem with the mpi environment here,
i have corrected that, thank you, i believe we are seeing the correct behaviour now.
Mike.
On Thu, Jan 29, 2015 at 5:15 PM, Mike Atambo <mikeat4999 at gmail.com<mailto:mikeat4999 at gmail.com>> wrote:
Mike (Heroux),
Thanks i will do this, and see what kind of information i get, i will post back what i find to
make it easier to for one of you to help (or explain what i may be missing).
Mike
On Thu, Jan 29, 2015 at 4:29 PM, Heroux, Mike <MHeroux at csbsju.edu<mailto:MHeroux at csbsju.edu>> wrote:
Mike,
Just to follow up a bit more: The reason I suggest this manual approach is to determine if your MPI environment can scale properly. If your cores are on a single workstation, you will not get full speed up on this kind of solver, but I am surprised you are not seeing any. This test would help diagnose the issue.
Mike
From: <Heroux>, "maherou at sandia.gov<mailto:maherou at sandia.gov>" <maherou at sandia.gov<mailto:maherou at sandia.gov>>
Date: Thursday, January 29, 2015 at 1:03 PM
To: Mike Atambo <mikeat4999 at gmail.com<mailto:mikeat4999 at gmail.com>>, "Trilinos-Users at software.sandia.gov<mailto:Trilinos-Users at software.sandia.gov>" <Trilinos-Users at software.sandia.gov<mailto:Trilinos-Users at software.sandia.gov>>
Subject: Re: [Trilinos-Users] scaling with trilinos tpetra and anasazi solvers
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<mailto:trilinos-users-bounces at software.sandia.gov> <trilinos-users-bounces at software.sandia.gov<mailto:trilinos-users-bounces at software.sandia.gov>> on behalf of Mike Atambo <mikeat4999 at gmail.com<mailto:mikeat4999 at gmail.com>>
Sent: Monday, January 26, 2015 7:29 AM
To: Trilinos-Users at software.sandia.gov<mailto: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
--
M. O. Atambo
mikeat4999 at gmail.com<mailto:mikeat4999 at gmail.com>
matambo at ictp.it<mailto:matambo at ictp.it>
Ext .139
Room 209.
--
M. O. Atambo
mikeat4999 at gmail.com<mailto:mikeat4999 at gmail.com>
matambo at ictp.it<mailto:matambo at ictp.it>
Ext .139
Room 209.
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