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Subject: Re: [OMPI users] Open-MPI and gprof
From: jgans (jgans_at_[hidden])
Date: 2009-04-22 19:37:05


Hi,

Yes you can profile MPI applications by compiling with -pg. However, by
default each process will produce an output file called "gmon.out",
which is a problem if all processes are writing to the same global file
system (i.e. all processes will try to write to the same file).

There is an undocumented feature of gprof that allows you to specify the
filename for profiling output via the environment variable
GMON_OUT_PREFIX. For example, one can set this variable in the .bashrc
file for every node to insure unique profile filenames, i.e.:

export GMON_OUT_PREFIX='gmon.out-'`/bin/uname -n`

The filename will appear as GMON_OUT_PREFIX.pid, where pid is the
process id on a given node (so this will work when multiple nodes are
contained in a single host).

Regards,

Jason

Tiago Almeida wrote:
> Hi,
> I've never done this, but I believe that an executable compiled with
> profilling support (-pg) will generate the gmon.out file in its
> current directory, regardless of running under MPI or not. So I think
> that you'll have a gmon.out on each node and therefore you can "gprof"
> them independently.
>
> Best regards,
> Tiago Almeida
> ---------------------------------
> jody wrote:
>> Hi
>> I wanted to profile my application using gprof, and proceeded like
>> when profiling a normal application:
>> - compile everything with option -pg
>> - run application
>> - call gprof
>> This returns a normal-looking output, but i don't know
>> whether this is the data for node 0 only or accumulated for all nodes.
>>
>> Does anybody have experience in profiling parallel applications?
>> Is there a way to have profile data for each node separately?
>> If not, is there another profiling tool which can?
>>
>> Thank You
>> Jody
>> _______________________________________________
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>> http://www.open-mpi.org/mailman/listinfo.cgi/users
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>>
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