Jeff McWhirter was studying whether he could speed up IDV data access by multithreading on the client. He put together a test which fetched the same data over and over, with 1-10 client threads.
This is hitting motherlode TDS, which has 2 quad-core processors, running solaris x86 and ZFS. It asks for one field from an NCEP model file, stored in GRIB1 compression, so theres some amount of computation. Actual URL:
19 * 65 *93 = 114855 floats = 459K bytes.
The result shows that you can't get more than 2.5x speedup in this particular case. I will try this on netcdf files, which should be only pure IO. Also interesting to see if the opendap stack causes significant overhead.
A more realistic test is to ask for successive time slices of non-cached data. These may be better opportunities for overlapping IO.
