[mpich2-dev] No Gain For calculating maximum of an array

Fri Nov 9 13:28:55 CST 2012

Thanks a lot for the answers!

I have calculated the maximum element of an array that has around 5*10^7
elements, but there were still no gains!
Is the code correct?
I have reattached the program file for your kind reference.

I would like to request some more guidance on the results.

As i mentioned, the results that i get from embarrassingly parallel
problems are not at all surprising .
The plots are (
https://github.com/madaan/BVP-MPI-PROJECT/blob/master/PI/PI.png) and (
https://github.com/madaan/BVP-MPI-PROJECT/blob/master/SumNELe/Sigma%28N%29.png)
.

The setup is as follows :

*Node configuration*
There are 3 similar nodes, each consisting of an Intel(R) Pentium(R) 4 CPU,
2.60GHz with 512 MB of memory. Each processor has 512 KB cache.

 Another node has an Intel Core i3-330M, 2.13GHz with 3GB of memory. It is
termed *FOX* for reference . All the nodes runs Ubuntu 12.04 Long term
support version.

*Network setup:*
Nodes are interconnected via a fast Ethernet switch (10 MB/s). The network
configuration is essentially meshed. For all tests the MPI/Pro library from
MPI Software Technology (MPI/Pro distribution version 1.6.3).

The aim of the project is to compare the computing power of a group of
dumped machines  with a state of the art ( or so i say ) computer, called
the fox for reference.

We call the project *Junk Computing*.

I request your thoughts /comments /criticism .

I also request suggestions for some simple benchmarking programs that i can
write.

Thanks for the precious time.

With regards

On Fri, Nov 9, 2012 at 11:30 PM, <mpich2-dev-request at mcs.anl.gov> wrote:

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> Today's Topics:
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>    1. Re:  mpich2-dev Digest, Vol 47, Issue 3
>       (Muhammad Zulfikar Handana)
>    2.  No Gain For calculating maximum of an array (Aman Madaan)
>    3. Re:  No Gain For calculating maximum of an array (Jeff Hammond)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Fri, 9 Nov 2012 14:28:04 +0700
> From: Muhammad Zulfikar Handana <zulfikarhandana at gmail.com>
> To: mpich2-dev at mcs.anl.gov
> Subject: Re: [mpich2-dev] mpich2-dev Digest, Vol 47, Issue 3
> Message-ID:
>         <CAN0Ct=3J9cmmDeXY96qcoJW+iLQvc705QuxWuW=
> rGYeSPv1+Ug at mail.gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Thanks jeff for your answer and i have another question
>  so thats mean, MPICH2 must be modified before we have setting manually
> that message protocol?
>
> Thanks
>
> Handana
>
> >
> > Message: 4
> > Date: Mon, 5 Nov 2012 23:18:11 -0500
> > From: Jeff Hammond <jhammond at alcf.anl.gov>
> > To: mpich2-dev at mcs.anl.gov
> > Subject: Re: [mpich2-dev] setting manually eager to rendezvous
> > Message-ID:
> >         <CAGKz=uKP2D0mut=
> > P92SLR6D00A_9n6KcJWO8fqFppiotYfDz3g at mail.gmail.com>
> > Content-Type: text/plain; charset=ISO-8859-1
> >
> > Please post user questions to mpich-discuss at mcs.anl.gov.  This list is
> > for developers of MPICH2 and those who may be modifying the
> > implementation.
> >
> > In this case, those environment variables are not relevant unless you
> > have Blue Gene/P, and in that case, MPICH2 1.4 will not work anyways.
> >
> > If you want to know about eager vs. rendezvous, perhaps you can
> > re-post this question on the user list and someone will answer
> > regarding the settings for ch3.
> >
> > Best,
> >
> > Jeff
> >
> > On Mon, Nov 5, 2012 at 10:46 PM, Muhammad Zulfikar Handana
> > <zulfikarhandana at gmail.com> wrote:
> > > Hi, iam Handana. this my first project using MPICH2, i have little
> > confused
> > > because i dont know how to setting manually eager to rendezvous at
> MPICH2
> > > 1.41p1. i have a read this using code
> > >
> > > DCMF_EAGER -
> > > DCMF_RZV -
> > >
> > > am i right? or there is another code? thank you very much for your
> > attention
> >
> >
> >
> > --
> > Jeff Hammond
> > Argonne Leadership Computing Facility
> > University of Chicago Computation Institute
> > jhammond at alcf.anl.gov / (630) 252-5381
> > http://www.linkedin.com/in/jeffhammond
> > https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond
> >
> >
> > ------------------------------
> >
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>
> Message: 2
> Date: Fri, 9 Nov 2012 13:17:14 +0530
> From: Aman Madaan <madaan.amanmadaan at gmail.com>
> To: mpich2-dev at mcs.anl.gov
> Subject: [mpich2-dev] No Gain For calculating maximum of an array
> Message-ID:
>         <
> CA+h7vmBLxppUR88uahVrbxNeTQKbnOy+HC5qajGF127Xn9BPUw at mail.gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hello
>
> I am pretty new to MPI programming and i was doing some research on
> performance of dumped computers in our college.
> Although my cluster is giving the expected gain for many embarrassingly
> parallel problems,but the attached simple program for calculating maximum
> number in an array is unexpectedly slow.
>
> The file of numbers is first read at the root and the array is scattered to
> all the supporting nodes. Then MPI_REDUCE is used to get the global maximum
> .
>
> The result of running the program are as follows :
>
> *Using 2 nodes : *
>
> axiom at node1:~/Programs/largest$ mpiexec -f f ./a.out numbers/num10000.txt
> 10000
>
> Maximum = 3999213
>
> wall clock time = 0.002819
>
> *Using single node : *
>
> axiom at node1:~/Programs/largest$ mpiexec  ./a.out numbers/num10000.txt
> 10000
>
> Maximum = 3999213
>
> wall clock time = 0.000168
>
> ..........
>
> The situation remains same even after increasing the number of elements.
>
> I request your suggestions.
>
> Thanks a lot for your time.
>
>
> With regards
>
>
> --
>
> Aman Madaan
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> ------------------------------
>
> Message: 3
> Date: Fri, 9 Nov 2012 08:42:07 -0600
> From: Jeff Hammond <jhammond at alcf.anl.gov>
> To: mpich2-dev at mcs.anl.gov, madaan.amanmadaan at gmail.com
> Subject: Re: [mpich2-dev] No Gain For calculating maximum of an array
> Message-ID:
>         <CAGKz=u+2aQytQvDum1ENYqqwXwsHSStFu=
> HceeqRfV3e5xSQqA at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> Please resend to mpich-discuss at mcs.anl.gov.
>
> Jeff
>
> On Fri, Nov 9, 2012 at 1:47 AM, Aman Madaan <madaan.amanmadaan at gmail.com>
> wrote:
> >
> > Hello
> >
> > I am pretty new to MPI programming and i was doing some research on
> > performance of dumped computers in our college.
> > Although my cluster is giving the expected gain for many embarrassingly
> > parallel problems,but the attached simple program for calculating maximum
> > number in an array is unexpectedly slow.
> >
> > The file of numbers is first read at the root and the array is scattered
> to
> > all the supporting nodes. Then MPI_REDUCE is used to get the global
> maximum
> > .
> >
> > The result of running the program are as follows :
> >
> > Using 2 nodes :
> >
> > axiom at node1:~/Programs/largest$ mpiexec -f f ./a.out
> numbers/num10000.txt
> > 10000
> >
> > Maximum = 3999213
> >
> > wall clock time = 0.002819
> >
> > Using single node :
> >
> > axiom at node1:~/Programs/largest$ mpiexec  ./a.out numbers/num10000.txt
> 10000
> >
> > Maximum = 3999213
> >
> > wall clock time = 0.000168
> >
> > ..........
> >
> > The situation remains same even after increasing the number of elements.
> >
> > I request your suggestions.
> >
> > Thanks a lot for your time.
> >
> >
> > With regards
> >
> >
> >
> > --
> >
> > Aman Madaan
>
>
>
> --
> Jeff Hammond
> Argonne Leadership Computing Facility
> University of Chicago Computation Institute
> jhammond at alcf.anl.gov / (630) 252-5381
> http://www.linkedin.com/in/jeffhammond
> https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond
>
>
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> End of mpich2-dev Digest, Vol 47, Issue 4
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>

-- 

Aman Madaan
+91-9958725963
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