[daip] AIPS on 64 bit processor

[Hanno Spreeuw]

Thanks,
so in my case, low frequency data, lots of facets, sometimes many 
selfcal iterations, it seems advantageous to have a 64 bit processor and 
up to 6 GB RAM.
Hanno.

Eric Greisen schreef:
> 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