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

[netCDF #NNS-961385]: nf90_put_var slows down erratically

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 Note that the archive is no longer being updated. We provide the archive for reference; many of the answers presented here remain technically correct, even if somewhat outdated.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: [netCDF #NNS-961385]: nf90_put_var slows down erratically
  • Date: Tue, 29 Jul 2008 06:58:57 -0600
> Ed,
>
> Please please please disregard.  I clearly need to go home.  I had the wrong
> path to the new libraries.
>
> Yes, it compiles beautifully.  There are still hiccups in there (writes that
> take 100 times longer than average), but it is still much faster than
> netcdf-3.
>
> David
>
>

OK, but that erratic slowdown might not be a bug.

HDF5 does a lot behind the scenes, including caching. So it may be that the
hiccups are caused by the file data cache finally getting enough new data to
require a disk I/O operation.

One way to check would be to turn on a profiler and see what functions are
being called during these hiccups.

Unfortunately, at the moment, there is no way to control the cache size from
netcdf-4 (you can control its size from HDF5.) I do intend to add that
capability in a future release.

Please let us know if you have any further results. Are you planning on writing
this up for publication anywhere?

Thanks!

Ed

Ticket Details
===================
Ticket ID: NNS-961385
Department: Support netCDF
Priority: Normal
Status: Closed