The OPAL Discussion Forum

[christof kraus <christof.j.kraus AT gmail.com>]

Hi,

suppose it were the interconnection, does this then make sense:

* start cite Normans first email *******
When it's being run, all 8 cpu cores are active, but only one is doing the
calculations. Furthermore, this run actually took an hour more than a previous
run using a single core
* end cite Normans first email *********
?

christof
On Tue, Nov 29, 2011 at 7:03 AM, Andreas Adelmann
<andreas.adelmann AT psi.ch> wrote:
> Hello Norman
>
> I need to know how many cores trcompdev.triumf.ca has.
> You are requesting 8 cores on one node (trcompdev.triumf.ca)
> maybe you are simply overloading trcompdev.
>
> One other thing you have to be aware of is the interconnect bandwidth:
> Gigabit will not work and you have in such a case the very same effect
> that you are observing. Again Fred know all this. And YES the FFT based
> solver
> scales very well iff you have a fast interconnect.
>
> I also observer that you are using O(2E6) grid points with only 5E4
> particles.
> Your grid is far to large! Per grid point you should have on the average 10
> ... 40
> particles.
>
> My advice:
>
> a) check the how much steam you nodes has
>
> b) do you use a fast interconnect?
>
> c) reduce the size of the grid or increase the number of particles.
> NP=5E4 -> G= 16x16x16
>
>  Cheers Andreas
>
>
>
> On Nov 28, 2011, at 10:40 PM, Norman Huang wrote:
>
> Hi Andreas,
>
> Here's the stdout output.
>
> Using this configuration, a run takes about 3.5 hours. While using a single
> node only takes 2 hours.
>
> The Pi calculation test was successful, so I think OpenMPI is installed
> correctly. Does FFT actually
> exploit parallel processing, or do I have to use multigrid instead?
>
> Regards,
> Norman
>
> ________________________________
> Subject: Re: Enabling Parallel Computing on OPAL-T
> From: andreas.adelmann AT psi.ch
> Date: Sat, 26 Nov 2011 08:45:35 +0100
> CC: opal AT lists.psi.ch; raoyn AT triumf.ca; krab AT triumf.ca; tplanche AT triumf.ca; 
> fwj AT triumf.ca
> To: norman-huang AT hotmail.com
>
> Hello Norman the input files is just fine, I made one small change not
> related to your problem.
>
> Can you send me the std-output of your run? On which cluster do you run?
>
> Are you sure that MPI is installed properly i.e. can you run a canonical MPI
> test - for example
> calculating Pi - (this test comes with every MPI distribution).
>
> You should also contact Fred Jones, I remember having similar problems when
> I was at Triumf
> in the beginning of this year.
>
> Cheers Andreas
>
>
>
>
>
>
>
>
> On Nov 26, 2011, at 2:54 AM, Norman Huang wrote:
>
> Hi Andreas,
>
> I'm trying to do space charge calculations using parallel computing on
> OPAL-T, but
> it appears only 1 core is being used.
>
> This is my fieldsolver parameters:
>
> Fs1:FIELDSOLVER, FSTYPE=fft, MX=32, MY=32, MT=2024,
> PARFFTX=true, PARFFTY=true, PARFFTT=false,
> BCFFTX=open, BCFFTY=open, BCFFTT=open,
> BBOXINCR=1, GREENSF=INTEGRATED;
>
>
> Command used to run the test 'isis.in': mpirun -np 8 opal --commlib mpi
> isis.in
>
> When it's being run, all 8 cpu cores are active, but only one is doing the
> calculations. Furthermore, this run actually took an hour more than a
> previous
> run using a single core.
>
> Am I missing some configurations?
>
> Regards,
> Norman
> <isis.in>
>
>
> ------
> Dr. sc. math. Andreas (Andy) Adelmann
> Staff Scientist
> Paul Scherrer Institut WLGB/132 CH-5232 Villigen PSI
> Phone Office: xx41 56 310 42 33 Fax: xx41 56 310 31 91
> Phone Home: xx41 62 891 91 44
> -------------------------------------------------------
> Thursdays: ETH CAB H 83.1  +41 44 632 36 72
> ============================================
> The more exotic, the more abstract the knowledge,
> the more profound will be its consequences.
> Leon Lederman
> ============================================
>
>
>
> <stdout.txt>
>
>
> ------
> Dr. sc. math. Andreas (Andy) Adelmann
> Staff Scientist
> Paul Scherrer Institut WLGB/132 CH-5232 Villigen PSI
> Phone Office: xx41 56 310 42 33 Fax: xx41 56 310 31 91
> Phone Home: xx41 62 891 91 44
> -------------------------------------------------------
> Thursdays: ETH CAB H 83.1  +41 44 632 36 72
> ============================================
> The more exotic, the more abstract the knowledge,
> the more profound will be its consequences.
> Leon Lederman
> ============================================
>
>
>