benchmark program question

[Wei-keng Liao]

Hi,

IOR benchmark includes pnetcdf. http://sourceforge.net/projects/ior-sio 
Its pnetcdf was recently modified to use record variables. That should 
take care of the file appending I/O mode.

I am interested in your results of 26 GB/s on Lustre using MPI-IO on 
shared files. My experience was about 15 GB/s top on Jaguar @ORNL using an 
application I/O kernel whose data partitioning patterns are 3D 
block-block-block. But the results were obtained when Jaguar was running 
catamount. Jaguar is currently under upgrade to new hardware and software. 
I would appreciate if you can share your results.

Wei-keng


On Tue, 26 Feb 2008, Marty Barnaby wrote:

> I'm new to the parallel NetCDF interface, and I don't have much 
> experience with NetCDF either. Because of new interest on our part, we 
> would like to have a straightforward, benchmark program to get byte-rate 
> metrics for writing to a Posix FS (chiefly, some large Lustre 
> deployments). I've had some reasonable experiences in this at the MPI-IO 
> level, achieving a sustained, average rate of 26 GB/s; this writing to a 
> single, shared file with an LFS stripe-count of 160. If anyone is 
> interested, I could provide them with more specifics.
> 
> I can't find the benchmark-type code that I really need, though I've 
> been looking at the material under /test like /test_double/test_write.c 
> This I've compiled and executed successfully at the appropriate -np 4 
> level.
> 
> There are three dynamics I would like to have that I can't see how to 
> get.
> 
>   1. Run on any number of processors. I'm sure this is simple, but I want to
>       know where the failure is when I attempt it.
> 
>   2. Set the number of bytes appended to an open file in a single, atomic,
>       collective write operation. In my MPI-IO benchmark program I merely
>       got this number by having a buffer size on each processor, and 
> the total
>       was the product of this times the number of processors. At the higher
>       level of PNetCDF I'm not sure which value I'm getting in the def_var
>       and put_var.
> 
>   3. Be able to perform any number of equivalent, collective write operations,
>       appending to the same, open file. Simply a:
> 
>       for ( i = 0; i < NUMRECS; i++ )
> 
>       concept. This is basically what our scientific, simulation applications
> do in their 'dump' mode.
> 
> 
> Thanks,
> Marty Barnaby
>