[ale] OT: AMD Athlon 64

[James P. Kinney III]

> I'm reading about this processor now, and I see:
> 	256 Tb of memory address space.
> I'm no processor buff . . . but above that it mentions that the
> processor can eliminate the 4Gb limit on ram.
>
> <_<
>>_>
>
> I'm picturing a PC that runs the power grid for a small city.
>
> It also says that it can run both 32bit and 64bit operating systems. I
> see a lot more computers being sold (like at Sam's club, e.g.) with
> 64's. Do you think the majority of applications are also going to be
> written for 64's in the near future, or is it going to be a while?
>
> Jesse M. Holmes
>

64-bit is not important for most things. Word processing, for example,
gains nothing from 64-bit. Heavy numerical calculations (nuclear physics,
engineering, statistical stuff, heavy graphics, etc) do benefit. For the
personal computer user, 64-bit is best used for loads of RAM. As the
opteron series can run both 32 AND 64-bit code, it is the best of both
worlds. Theoretically, a 64-bit CPU and OS _should_ be able to run 2
32-bit processes nearly simultanously using virtualization.

Rewriting apps for 64-bit is not a trivial process. Nearly all of the
direct memory management section must be completely reworked if they were
not written to support per-system memory allocation arrangements. Much of
Linux stuff has been 64-bit safe for a while. This makes it easy to
recompile the same source code on a 64-bit system and get a working
binary. It most likely won't be very optomized without some manual code
tweaks. Most 64-bit Linux distros also ship with a bunch of 32-bit libs
for those apps that can't be run in 64-bit mode. This also provides
support for legacy code as well.

If someone is looking at buying a new system and they have deep pockets,
64-bit is a good choice. AMD Opterons are kicking Intel Itaniums
everywhere possible. The 64-bit Linux distros have been out long enough
that the polish is on them and they work just about like the 32-bit ones
do. For a long time, there was no 64-bit java for linux. As linux was the
preferred server OS for Opterons, that was a problem for the tomcat crowd.
That has been fixed.