[bananas] New "architecture" now supported in AIPS

[Eric Greisen]

Those of you running a MNJ regularly may have noticed that a new 
architecture called LNX64 is now supported in AIPS.  It uses a very 
recent version of the Intel compiler run on a 64-bit Linux computer.
Many computers these days are 64-bit in their hardware and, at least at 
NRAO, many are now getting 64-bit based operating systems (RedHat 5 at 
NRAO).  We have tested the new version and it appears to get a modest 
(about 10%) improvement in performance compared to the 32-bit "LINUX" 
load modules prepared with a somewhat older version of the Intel 
compiler even on modest-memory, older Pentium IV systems.  This LNX64 
also allows the user to throw a lot of memory at the pseudo-AP to deal 
with really large imaging problems (see last 2 AIPSLetters).  Whether 
this is a good idea or not depends on how much memory the computer has 
and what else is going on at the time.

New installations on 64-bit machines will be asked to confirm their 
architecture as LNX64 by install.pl.  You may confirm it or change to 
LINUX as you wish.  Changing an existing installation to LNX64 from 
LINUX is a bit more complicated.  I would recommend running install.pl 
using the existing $AIPS_ROOT but selecting LNX64 architecture - be sure 
to edit $AIPS_ROOT/HOSTS.LIST in advance to specify that the computer 
you are using is LNX64.  Simply changing the architecture and running 
the MNJ might get cvs and rsync to copy a lot of stuff, but it will not 
set up the new $SYSLOCAL area that you will require.

I should warn you that we have run some tests on LNX64 and a few users 
at NRAO are now using it.  However, it has not had the level of testing 
that the large body of AIPS users give to the LINUX version every week.

We expect to try testing multi-threading and other performance 
enhancements using this new architecture.

Eric Greisen