[Darshan-users] Information on a graph

[Phil Carns]

On 06/27/2014 11:04 AM, Matthieu Dorier wrote:
> Hi Darshan users/dev
>
> I would like some precisions about the first graph in the darshan pdf 
> summary (see attached for example).
> There are two bars, one for POSIX and one for MPI-I/O. So if I 
> understand correctly, MPI-I/O calls in the POSIX bar will appear in 
> purple (label "other"), and so will the POSIX operations in the 
> MPI-I/O bar, correct?
>

Hi Matthieu,

Not exactly.  An example might be the best way to clarify.   Imagine a 
job that runs for 100 seconds.  It does an MPI_File_Write for 50 
seconds, and that MPI_File_write internally calls a POSIX write for 25 
seconds.  The MPI graph will be 50% green and 50% purple.  The POSIX 
graph will be 25% green and 75% purple.

Since the POSIX operation was generated as a step within the MPI-IO 
operation, it will count towards the MPI-IO write time in the MPI-IO graph.

If you wanted to find out how much time was spent by MPI-IO *not* 
including the POSIX operations, then you will have to subtract that out 
manually.  We don't have a graph showing that.

thanks,
-Phil

> Thanks,
>
> Matthieu Dorier
> PhD student at ENS Rennes
> http://people.irisa.fr/Matthieu.Dorier
>

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