benchmark program question

[Rob Ross]

Hi Marty, I think that IOR (from LLNL) will let you do this stuff. --  
Rob

On Feb 26, 2008, at 10:22 AM, 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
>