Re: [netcdfgroup] performance issues

• To: Karsten Bolding <karsten@xxxxxxxxxxxxxxxxxxxx>
• Subject: Re: [netcdfgroup] performance issues
• From: Ted Mansell <ted.mansell@xxxxxxxx>
• Date: Wed, 18 Jan 2012 09:15:34 -0600

Does the recompile switch on netcdf4 features, or is it still writing a classic 
nc3 file using the nc4 libs?  Just to clarify -- Not that I know if that makes 
a difference.

-- Ted

On Jan 18, 2012, at 2:10 AM, Karsten Bolding wrote:

> Hello
> 
> I'm working on a 1D ocean model that stores its output in NetCDF.
> 
> With NetCDF4 I've experienced some performance issues as shown in the
> timings below for a specific model run:
> 
> NetCDF4:
> real  0m42.940s
> user  0m3.630s
> sys   0m0.110s
> 
> NetCDF 3.6.3:
> real  0m1.838s
> user  0m1.820s
> sys   0m0.000s
> 
> Its run on the same system only recompiling the executable to link
> either NetCDF 3 or 4.
> 
> Disk performance is not an issue:
> /dev/sda:
> Timing buffered disk reads: 344 MB in  3.02 seconds = 114.06 MB/sec
> 
> as the resulting file is only 10MB.
> 
> I'm using the 4.2 release candidate configured as follows:
> 
> C:
> CPPFLAGS=-I/opt/hdf5/include LDFLAGS=-L/opt/hdf5/lib  ./configure
> --prefix=/opt/netcdf-${netcdf_ver}_IFORT 
> 
> Fortran:
> FFLAGS="-O3" FC=ifort F77=ifort CPPFLAGS=-I/opt/hdf5/include CFLAGS="-O3" 
> LDFLAG S=-L/opt/hdf5/lib  ./configure --prefix=/opt/netcdf-${netcdf_ver}_IFORT
> 
> i.e. no specific optimisation. 
> 
> Netcdf 3.6.3 is also compiled without specific optimisation.
> 
> Any ideas anyone?
> 
> Karsten
> 
> PS: I've done the above simulations a number of times with consistent
> results.
> 
> 
> -- 
> ----------------------------------------------------------------------
> Karsten Bolding                    Bolding & Burchard ApS
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> 
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> 
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> A: Almost the same as goldy and bronzy - just made of iron ...
> (from Blackadder)
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