[mpich-discuss] Poor MPICH Performance on Windows Vista vs. XP

[Jayesh Krishna]

Hi,
 The default channel used by MPICH2 on windows is the sock channel (all MPI communication is performed using tcp sockets). The nemesis channel performs local (same node) communication using shared memory and remote (across nodes) communication using tcp sockets (on windows) .

Regards,
Jayesh
----- Original Message -----
From: "Rahul Mukerjee" <r.mukerjee at gmail.com>
To: "Jayesh Krishna" <jayesh at mcs.anl.gov>
Cc: mpich-discuss at mcs.anl.gov
Sent: Thursday, October 29, 2009 5:34:17 PM GMT -06:00 US/Canada Central
Subject: Re: [mpich-discuss] Poor MPICH Performance on Windows Vista vs. XP

Hi Jayesh,

I installed the latest release, 1.2 of MPICH2 on the Vista machines.
The -channel nemesis option showed impressive gains. Here are the
results:

3 hosts: Time = 0.354110 secs
4 hosts: Time = 13.612531 secs
5 hosts: Time = 13.849166 secs

With -channel nemesis:
3 hosts: Time = 0.045664 secs
4 hosts: Time = 0.253233 secs
5 hosts: Time = 0.270557 secs

Can you please tell me what exactly was the issue here? Also, I am yet
to test on the XP machines but I am assuming that this option will
perform equally well there. Is that correct? And finally, I'd also
like to mention that I had seen very poor scalability for my
application on a quad-core machine with the -localonly option. I hope
to see some dramatic improvements with the 'nemesis'. Please correct
me if I am wrong.

Thank you very much for your help.

Sincerely,

Rahul Mukerjee.

On Thu, Oct 29, 2009 at 12:52 PM, Jayesh Krishna <jayesh at mcs.anl.gov> wrote:
> Hi,
>  Oh... and try the latest stable release, 1.2, of MPICH2 (1.0.8 is old) available at http://www.mcs.anl.gov/research/projects/mpich2/downloads/index.php?s=downloads .
>  Let us know your findings.
>
> (PS: With WinXP make sure that you have SP3 installed before installing MPICH2.)
> Regards,
> Jayesh
> ----- Original Message -----
> From: "Jayesh Krishna" <jayesh at mcs.anl.gov>
> To: "r mukerjee" <r.mukerjee at gmail.com>
> Cc: mpich-discuss at mcs.anl.gov
> Sent: Thursday, October 29, 2009 12:47:39 PM GMT -06:00 US/Canada Central
> Subject: Re: [mpich-discuss] Poor MPICH Performance on Windows Vista vs. XP
>
> Hi,
>  Did you try the nemesis channel (mpiexec -n 2 -channel nemesis barrier_test.exe)?
>
> Regards,
> Jayesh
> ----- Original Message -----
> From: "Rahul Mukerjee" <r.mukerjee at gmail.com>
> To: mpich-discuss at mcs.anl.gov
> Sent: Thursday, October 29, 2009 12:17:01 PM GMT -06:00 US/Canada Central
> Subject: [mpich-discuss] Poor MPICH Performance on Windows Vista vs. XP
>
> Hi,
>
> I am using MPICH2 version 1.0.8p1. I am using a simple C code to
> measure the time taken for 100 MPI_BARRIER calls in Windows Vista vs.
> XP. Here is the code:
>
> #include "mpi.h"
> #include <stdio.h>
> #include <stdlib.h>
> int main(int argc, char **argv)
> {
>    int cpuid, ncpu;
>    int i, count;
>    double t1, t2, sum;
>    count = 100;
>    sum = 0.0;
>    MPI_Init(&argc, &argv);
>    MPI_Comm_size(MPI_COMM_WORLD, &ncpu);
>    MPI_Comm_rank(MPI_COMM_WORLD, &cpuid);
>    printf("NCPU:%d, CPUID:%d\n", ncpu, cpuid);
>    fflush(stdout);
>    printf("start barrier\n"); fflush(stdout);
>    for (i=0; i<count; i++)
>        {
>                t1 = MPI_Wtime();
>                MPI_Barrier(MPI_COMM_WORLD);
>                t2 = MPI_Wtime();
>                if (cpuid == 0) sum = sum + (t2 - t1);
>        }
>        printf("end barrier\n"); fflush(stdout);
>        if (cpuid == 0) printf("Time = %lf\n", sum);
>        MPI_Finalize();
>    return 0;
> }
>
> The results are:
>
> Windows XP:
> 3 hosts: Time = 0.034093 secs
> 4 hosts: Time = 0.041328 secs
>
> Windows Vista:
> 3 hosts: Time = 0.347072 secs (Slow, but still bearable)
> 4 hosts: Time = 11.820926 secs (WTF???)
>
> Someone had posted earlier about poor MPICH performance with HPC
> Server 2008 / Vista. This is in continuation of that, in a way. Any
> help would be greatly appreciated. Thank you.
>
> Sincerely,
>
> Rahul Mukerjee.
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