[mpich-discuss] [mpich2-maint] Problems with time and stdin

ephi.maglaras-cssi at snecma.fr ephi.maglaras-cssi at snecma.fr
Thu Nov 19 09:08:56 CST 2009

Can someone from the support give me an answer which solves or not my 
problems, please ? Thanks !

13/11/2009 11:25

Anthony Chan <chan at mcs.anl.gov>
Alain DEGUEIL/FP/SPS at SPS, mpich-discuss at mcs.anl.gov, Yves 
Re: [mpich2-maint] Problems with time and stdin

Do you mean that "time" returns the time of communications between 
processors ? So we probably don't have the same "time" command.
I gave the comparison with intel MPI in order to show what are the results 
of "time" on our system ("man time"), it's not a problem with intel MPI : 
 - "real time" is the wall time, i.e. the elapsed real time between 
invocation and termination. It's about 10 seconds for the job, with MPI or 
 - "user time" is the CPU time, i.e. the sum of CPU time of all 
processors. We are interested in this time for our statistics. So with 4 
processors, it's nearly 4*(real time). You can verify the result of "time" 
with the simple program "loop.f90" : compile and run it with the command 
"time". Here it gives 64.959s for the real time and 63.537s for the user 
CPU time. On our system, "time" returns the good value with an MPI job but 
not with an MPICH2 one. That is the problem which does not enable us to 
make statistics.
Please can you tell me if you have the same "time" command or not, for 
example by sending the result of "man time" ? Thank you.

As for the stdin problem, the test case I sent you (tutu.f90) does not 
have a too large stdin file, only 1000 lines, so why the stdin is not 
supported (error messages) ? It runs well with native MPI, with mpich (1), 
with lammpi but not with mpich2.
We don't have hydra and I can't modify the sources of my "real" program 
since it runs well with other mpis.
[rattachement "loop.f90" supprimé par Ephi MAGLARAS-CSSI/EXT/SPS] 
Thank you.
Best regards.

chan at mcs.anl.gov 
12/11/2009 21:58
Veuillez répondre à
Anthony Chan <chan at mcs.anl.gov>

mpich-discuss at mcs.anl.gov
Re: [mpich2-maint] Problems with time and stdin

Since this is a general MPICH usage question, I am forwarding
to mpich-discuss.

It seems you are comparing Intel MPI with MPICH2-1.0.8p1.
I don't have access to Intel MPI so don't know why the intel
MPI's uses so much user time on your simple program that
does not do any communication. Maybe you could contact Intel
MPI support for the answer.

What do you mean by "stdin files not well supported" ?
If the default process manager, mpd, does not fit your
need, you could try other process managers like hydra
(i.e. mpiexec.hydra) which is available though the latest
MPICH2 release, 1.2.1rc1.  If you want to read large amount
of data to rank 0 (or all ranks), you may want to open/read
the file on rank 0 (then broadcast the data to every ranks).


----- "ephi maglaras-cssi" <ephi.maglaras-cssi at snecma.fr> wrote:

> Dear,
> I meet 2 kind of problems when running an mpich2 job : 
>   - the "time" command does not give the user time
>   - stdin files are not well supported
> I compared mpich2 with native mpi. You can find test cases below (zip
> files), see README files for the problem descriptions.
> How can I solve these problems ?
> Thanks.
> Best regards.
> _______________________________________________
> mpich2-maint mailing list
> mpich2-maint at lists.mcs.anl.gov
> https://lists.mcs.anl.gov/mailman/listinfo/mpich2-maint
[rattachement "time.zip" supprimé par Ephi MAGLARAS-CSSI/EXT/SPS] 
[rattachement "stdin.zip" supprimé par Ephi MAGLARAS-CSSI/EXT/SPS] 

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