[mpich-discuss] Clarification needed on runningprocessesonMPICH2

Sun Nov 30 09:46:30 CST 2008

Then you can expect a slowdown if you run 6 processes on 4 cores.

  _____  

From: mpich-discuss-bounces at mcs.anl.gov
[mailto:mpich-discuss-bounces at mcs.anl.gov] On Behalf Of Waruna Ranasinghe
Sent: Saturday, November 29, 2008 11:32 PM
To: mpich-discuss at mcs.anl.gov
Subject: Re: [mpich-discuss] Clarification needed on
runningprocessesonMPICH2

no only 4

2008/11/30 Rajeev Thakur <thakur at mcs.anl.gov>

But you don't have 6 cores, do you?

  _____  

From: mpich-discuss-bounces at mcs.anl.gov
[mailto:mpich-discuss-bounces at mcs.anl.gov] On Behalf Of Waruna Ranasinghe

Sent: Saturday, November 29, 2008 11:03 PM 

To: mpich-discuss at mcs.anl.gov
Subject: Re: [mpich-discuss] Clarification needed on
runningprocessesonMPICH2

Yes, I'm sorry if you were miss led by my wordings.
I meant running two instances.

2008/11/30 Rajeev Thakur <thakur at mcs.anl.gov>

If you run two instances of mpiexec -n 3 tst, you are running a total of 6
processes, not 2 or 3. 

Rajeev

  _____  

From: mpich-discuss-bounces at mcs.anl.gov
[mailto:mpich-discuss-bounces at mcs.anl.gov] On Behalf Of Waruna Ranasinghe

Sent: Saturday, November 29, 2008 5:38 AM 

To: mpich-discuss at mcs.anl.gov
Subject: Re: [mpich-discuss] Clarification needed on
runningprocessesonMPICH2

>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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