[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Optimizations for Cray version of netCDF

This archive contains answers to questions sent to Unidata support through mid-2025. Note that the archive is no longer being updated. We provide the archive for reference; many of the answers presented here remain technically correct, even if somewhat outdated. For the most up-to-date information on the use of NSF Unidata software and data services, please consult the Software Documentation first.

  • Subject: Optimizations for Cray version of netCDF
  • Date: Thu, 20 Jun 1996 16:01:56 -0600
Oops, forgot to CC: support-netcdf on this reply ...

>From: "Bob Swanson" <address@hidden>
>Subject: Optimizations for Cray version of netCDF
>Organization: Lockheed Martin Technical Services
>Keywords: 199606201950.AA07255 netCDF Cray

Hi Bob,

> We have installed the latest 2.4.2 version of the
> netCDF library on our Cray C94. Our analysis of
> the performance, however, uncovered some unoptimized
> sections in the library for Cray use.
> 
> We have written 2 modifications to the library that:
> 
> *) improve the output side of our user's models dramatically
>       by making the "fill" function work the same
>       as the "write" function, utilizing the "xdr_floats"
>       function instead of "xdr_float".
> 
> *) improving error handling when a user's program runs out
>       of memory. With this new library's use of FFIO,
>       the memory requirements on the Cray are very high,
>       and a typical user job hits its memory limit while
>       executing. The default error handling system generates
>       garbled or empty error messages, complicating analysis
>       of the actual problem. Our suggested changes generate
>       a readable error message more often than the default
>       system.
> 
> If you are interested in the code for these two items, I
> will be happy to supply.

Thanks very much for your efforts and offer.  I've forwarded your note to
Steve Emmerson (address@hidden) and to Jeff Kuehn (address@hidden).
One or both of them will probably be interested in your code, and in
helping integrate the changes into our next version.

--Russ

______________________________________________________________________________

Russ Rew                                           UCAR Unidata Program
address@hidden                              http://www.unidata.ucar.edu