[daip] AIPS on 64 bit processor

[Eric Greisen]

Hanno Spreeuw wrote:
> Hello,
> 
> I am selecting a new desktop. Will runtimes for AIPS jobs improve 
> significantly with a 64 bit processor?
> 

Actually, I thought that almost all computers these days have 64-bit 
processors.  The difference now being whether the installed OS is 
configured for 32-bit or 64-bit execution.  So far, we only distribute 
32-bit binaries since that is the least common denominator.  However, we 
have just tested the latest Linux Intel compiler building in a 64-bit 
environment.  The resulting load modules ran faster on my machine (on 
old single-thread PIV cpu with 1 Gbyte ram) than did the 32-bit Intel 
modules we now distribute - about 10% faster.  How much of this is due 
to improvements in the compiler and how much to it being 64-bit I cannot 
say.  Note that on machines with lots of ram AIPS can use more ram on 
64-bit machines (up to 6 Gbytes or so) for pseudo-AP on problems 
involving lots of facets of freq-dependent modeling to reduce the disk 
I/O.  In some cases this should also be advantageous.

My initial remark is based on what is happening at NRAO.  We are 
changing everyone's desktop from a 32-bit RedHat 4 to a 64-bit RedHat 5 
OS with no change to the hardware.

If you are talking about a Mac however, we have no immediate plans to 
distribute 64-bit load modules for MACINT.

Eric Greisen