[mpich-discuss] measuring time in mpi program

[Jain, Rohit]

Hi Gurav,

Jumpshot requires building separate exec with -mpe option, takes huge memory to dump Clog2 file, and has performance overhead. Ofcourse, it gives more information (lot of it is hard to relate to fine-grained statistics), but it has its cost too.

So, we have lightweight time statistics collection code, that provides what we need for first level debugging. 
I recently came across a tool called IPM, which is supposedly very light weight and provide lot of statistics. We haven't used it though yet.

Regards,
Rohit


-----Original Message-----
From: mpich-discuss-bounces at mcs.anl.gov [mailto:mpich-discuss-bounces at mcs.anl.gov] On Behalf Of Mandar Gurav
Sent: Monday, February 28, 2011 1:03 AM
To: mpich-discuss at mcs.anl.gov
Subject: Re: [mpich-discuss] measuring time in mpi program

I think using Jumpshot will help you a lot more than you expected.
Please consult this page and don't bother about Installation of the
same. It is generally by default installed.

http://www.mcs.anl.gov/research/projects/perfvis/software/viewers/index.htm



On Fri, Feb 25, 2011 at 8:52 PM, Jain, Rohit <Rohit_Jain at mentor.com> wrote:
> Thanks.
> Rohit
>
> On Feb 25, 2011, at 20:23, "Gus Correa" <gus at ldeo.columbia.edu> wrote:
>
>> Gus Correa wrote:
>>> Jain, Rohit wrote:
>>>> Is there any performance data on using MPI_WTime()? How much time does
>>>> it typically take?
>>>>
>>>> We have lot of 'wait-send' and 'wait-receive' code at lot of places, and
>>>> we need to measure time spent in this sections. We currently use
>>>> gettimeofday() function to measure this time. Would MPI_WTime be faster
>>>> than that?
>>>>
>>>> Regards,
>>>> Rohit
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: mpich-discuss-bounces at mcs.anl.gov
>>>> [mailto:mpich-discuss-bounces at mcs.anl.gov] On Behalf Of Gus Correa
>>>> Sent: Friday, February 25, 2011 10:49 AM
>>>> To: Mpich Discuss
>>>> Subject: Re: [mpich-discuss] measuring time in mpi program
>>>>
>>>> hatem Elshazly wrote:
>>>>> hey guys,
>>>>>
>>>>> does anybody know how to measure execution time of mpi program?
>>>>> is there any option we can append in the mpirun\mpiexec command to measure time?
>>>>> is there any time command that measure clock cycle time, execution time,etc..?
>>>>>
>>>>>
>>>>> thank u very much
>>>>> hatem
>>>>>
>>>>>
>>>>>
>>>>
>>>> Hi Hatem
>>>>
>>>> The standard outline is something like this:
>>>>
>>>> ... initialize your MPI environment ...
>>>> start=MPI_Wtime()
>>>> ... do your work (including MPI calls)...
>>>> end=MPI_Wtime()
>>>> if (myrank .eq. 0) then
>>>>   print *, "Time spent (in seconds) is: ", end - start
>>>> endif
>>>> ... finalize MPI ...
>>>>
>>>> (You could also print the results from all ranks, if you want.)
>>>>
>>>> I my experience, perfomance tends to be quite variable if you don't have
>>>> a 'critical mass' of "do your work", i.e., if you do just a
>>>> couple of send/recv and get out.  Works better if your MPI calls
>>>> are on a loop in "do your work".
>>>>
>>>> I hope this helps.
>>>> Gus Correa
>>>>
>>>> PS - It looks like you managed to troubleshoot your network problems.
>>>> I hope so.
>>>> You never got back to the list on that subject.
>>> Hi Rohit
>>> I did a quick look at src/mpi/timer/mpidtime.c in MPICH2 1.3.1.
>>> You can check by yourself.
>>> It seems to me that MPI_WTime wraps gettimeofday.
>>> (For portability, perhaps?)
>>> The MPICH2 developers may clarify.
>>> Gus Correa
>>
>> Oops!
>> I just saw that Pavan already answered your question, Rohit.
>> Gus Correa
>>
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-- 
Mandar Gurav
http://www.mandargurav.org
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