[mpich-discuss] Clarification needed on runningprocessesonMPICH2

Sat Nov 29 05:38:19 CST 2008

>What do you mean by "one process" when it is clearly 3
>processes are running ?  When you say 2 processes of tst,
>do you mean you launched two instances of
>"mpiexec -n 3 ./tst" simultaneously.

Yes, I meant of launching two instances of "mpiexec -n 3 ./tst"
simultaneously.

I could not reach the MPICH cluster until monday, so that I'll send the
modified programme on Monday.

Thank You,
Waruna

2008/11/29 Anthony Chan <chan at mcs.anl.gov>

> >From your Readme file:
>
> > mpiexec -n 3 <path>
> >
> > output:
> > when only one process runs
> >
> > 0:Total: 499999999500000000 : Time: 9.272023
> > 2:Total: 499999999500000000 : Time: 10.722239
> > 1:Total: 499999999500000000 : Time: 11.324907
> >
> > When two processes of 'tst' runs in the same time
> >
> > 0:Total: 499999999500000000 : Time: 9.538206
> > 2:Total: 499999999500000000 : Time: 16.045104
> > 1:Total: 499999999500000000 : Time: 22.400754
>
> What do you mean by "one process" when it is clearly 3
> processes are running ?  When you say 2 processes of tst,
> do you mean you launched two instances of
> "mpiexec -n 3 ./tst" simultaneously.
>
> Could you add the following lines to your tst.cpp
>
>         char host_name[ MPI_MAX_PROCESSOR_NAME ];
>         int  namelen;
>         MPI_Get_processor_name( host_name, &namelen );
>         printf("rank %d running on %s\n", rank, host_name);
>
> before first fflush(stdout) to show the location of each process.
> Rerun your experiments and let us know the result.
>
> Also, you can use MPI_Wtime() instead of Duration.cpp that may
> simplify your test program.
>
> A.Chan
>
> ----- "Waruna Ranasinghe" <warunapww at gmail.com> wrote:
>
> > Hi Rajeev,
> > Here's test programme. It's just for testing. The results I got, are
> > in the
> > read me file in the attachment
> >
> > Thank You
> > Waruna
> >
> > 2008/11/27 Rajeev Thakur <thakur at mcs.anl.gov>
> >
> > >  In that case, what kind of program are you running? Can you send us
> > a
> > > small test program.
> > >
> > > Rajeev
> > >
> > >  ------------------------------
> > > *From:* mpich-discuss-bounces at mcs.anl.gov [mailto:
> > > mpich-discuss-bounces at mcs.anl.gov] *On Behalf Of *Waruna Ranasinghe
> > > *Sent:* Wednesday, November 26, 2008 9:05 PM
> > >
> > > *To:* mpich-discuss at mcs.anl.gov
> > > *Subject:* Re: [mpich-discuss] Clarification needed on
> > > runningprocessesonMPICH2
> > >
> > > Hi Rajeev,
> > > There's no doubt that process runs on all 3 machines.
> > > I have tried cpi example and it prints the hostnames of 3 machines
> > >
> > > mpiexec -l -n 3 <path to process>
> > > (the same path is available in all 3 machines)
> > >
> > > Thank you
> > > Waruna
> > >
> > >
> > > 2008/11/26 Rajeev Thakur <thakur at mcs.anl.gov>
> > >
> > >>  Make sure the processes are actually running on the 3 machines.
> > Try the
> > >> cpi example in the examples directory. It prints out the hostname.
> > How are
> > >> you running the job?
> > >>
> > >> Rajeev
> > >>
> > >>  ------------------------------
> > >>  *From:* mpich-discuss-bounces at mcs.anl.gov [mailto:
> > >> mpich-discuss-bounces at mcs.anl.gov] *On Behalf Of *Waruna
> > Ranasinghe
> > >> *Sent:* Wednesday, November 26, 2008 11:07 AM
> > >>
> > >> *To:* mpich-discuss at mcs.anl.gov
> > >> *Subject:* Re: [mpich-discuss] Clarification needed on running
> > >> processesonMPICH2
> > >>
> > >>   Fedora 8 - MPICH2 one machine with core-2-duo - master
> > >> two machines with one core
> > >> all together 3 nodes
> > >>
> > >> 2008/11/26 Rajeev Thakur <thakur at mcs.anl.gov>
> > >>
> > >>>  What kind of environment are you running on (how many machines,
> > how
> > >>> many cores each)?
> > >>>
> > >>> Rajeev
> > >>>
> > >>>  ------------------------------
> > >>>  *From:* mpich-discuss-bounces at mcs.anl.gov [mailto:
> > >>> mpich-discuss-bounces at mcs.anl.gov] *On Behalf Of *Waruna
> > Ranasinghe
> > >>> *Sent:* Wednesday, November 26, 2008 2:15 AM
> > >>> *To:* mpich-discuss at mcs.anl.gov
> > >>> *Subject:* Re: [mpich-discuss] Clarification needed on running
> > processes
> > >>> onMPICH2
> > >>>
> > >>>   Hi Anthony,
> > >>> I'm sorry, in this case I have to disagree with you.
> > >>> Because it is not max(t1,t2) but t1+t2 (this is the real result I
> > got)
> > >>> I use fflush(stdout) also
> > >>>
> > >>> What I think is that, Cluster runs two programmes alternatively.
> > >>> i.e. Process A runs for a while (say t3 seconds) then process B
> > for
> > >>> sometime and so on.
> > >>> Therefore, ultimately both the processes will run for t1+t2
> > >>>
> > >>> Cluster: MPICH2
> > >>> Fedora 8
> > >>>
> > >>> 2008/11/26 Anthony Chan <chan at mcs.anl.gov>
> > >>>
> > >>>>
> > >>>> If process A and B are launched by mpiexec, the time taken
> > >>>> by mpiexec should be max(t1,t2) not t1 + t2. As Rajeev said,
> > >>>> calling fflush(stdout) after each printf() is the fastest way
> > >>>> to get each process's stdout printed to your console.
> > >>>>
> > >>>> A.Chan
> > >>>>  ----- "Waruna Ranasinghe" <warunapww at gmail.com> wrote:
> > >>>>
> > >>>> > Hi Rajeev,
> > >>>> > Actually this is not what I'm talking about.
> > >>>> > Say there are processes A and B
> > >>>> > Process A utilize 100% of the cpu while it runs. The answer
> > will
> > >>>> > appear in
> > >>>> > t1 seconds
> > >>>> > Process B also utilize 100% of the cpu while it runs. The
> > answer will
> > >>>> > appear
> > >>>> > in t2 seconds
> > >>>> >
> > >>>> > When I run both the process A and B at the same time, The both
> > answers
> > >>>> > will
> > >>>> > appear in t1 + t2 seconds. where as I want to get the Process
> > A's
> > >>>> > answer
> > >>>> > first. (Here Process A is submitted before Process B)
> > >>>> >
> > >>>> > Is there anything that I can do to make this happen.
> > >>>> >
> > >>>> > Thank You,
> > >>>> > Waruna
> > >>>> >
> > >>>> > 2008/11/26 Rajeev Thakur <thakur at mcs.anl.gov>
> > >>>> >
> > >>>> > >  If you are refering to the output of "printf", you can try
> > adding
> > >>>> > an
> > >>>> > > fflush(stdout) after the printf. You don't have much control
> > over
> > >>>> > the order
> > >>>> > > in which it is printed from different processes.
> > >>>> > >
> > >>>> > > Rajeev
> > >>>> > >
> > >>>> > >  ------------------------------
> > >>>> > > *From:* mpich-discuss-bounces at mcs.anl.gov [mailto:
> > >>>> > > mpich-discuss-bounces at mcs.anl.gov] *On Behalf Of *Waruna
> > Ranasinghe
> > >>>> > > *Sent:* Tuesday, November 25, 2008 1:35 AM
> > >>>> > > *To:* mpich-discuss at mcs.anl.gov
> > >>>> > > *Subject:* [mpich-discuss] Clarification needed on running
> > processes
> > >>>> > on
> > >>>> > > MPICH2
> > >>>> > >
> > >>>> > > Hi all,
> > >>>> > > I submitted 3 processes at the same time using mpiexec. the
> > results
> > >>>> > of each
> > >>>> > > process appears only after all the processes have finished.
> > (I guess
> > >>>> > that
> > >>>> > > the way mpich schedule it).
> > >>>> > > What if I want to get the result of the process, which was
> > submitted
> > >>>> > first,
> > >>>> > > first. (like first in first out).
> > >>>> > >
> > >>>> > > I use MPICH2 cluster in Fedora 8 (with mpd)
> > >>>> > >
> > >>>> > > Thank you.
> > >>>> > > Waruna Ranasinghe
> > >>>> > >
> > >>>> > >
> > >>>>
> > >>>
> > >>>
> > >>
> > >
>
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