Re: 64-bit vs. 32-bit Computing

We say why 64 bit today? But in a few years (or decades) we'll look
back and laugh at why we even asked this question. It's not a really
fair comparison, but the original IBM PC with 640K of addressable memory
seemed like "plenty of space" when it first came out.

For us at SSL, we process data sets where it is a distinct advantage to
have 12 GB or more RAM. It's also even more useful, or should I say,
useful in more situations to have large disk volumes and huge files.
Now, I know that there are many 32 bit file systems which can handle 8
or 10 TB size. However, it gives me a warm fuzzy feeling to know that
there isn't some sort of thunking or other trickery going on underneath
to address all of this extra space.

Finally, I just have to say: why not go to 64 bit addressing? The small
slowdowns we see today with pointer copies or such will be a distant
memory in the near term. Feel the wide open spaces of 2^64. Pretty
soon you won't know how you got by without it.

Jon

Jon Forrest wrote:
> There's no doubt that for certain applications the
> increased address space provided by a 64-bit computer
> is a good thing. But, there aren't that many of these
> applications.
>
> Now that the new 64-bit Intel Core Duo/Solo processors are
> out, and now that new AMD Athlons are all 64-bit, I'm
> wondering when and why people are running them in
> 64-bit mode other than for database applications.
>
> I just did a quick test on a new Dell server with a Core Duo
> and 1GB of RAM. I loaded Fedora Core 5 in 32-bit mode and
> timed a build of a fairly big app (subversion). I then loaded
> Fedora Core 5 in 64-bit mode on the same PC, and timed the
> same build. I think this is a reasonable test since
> it does a lot of both I/O and computation. The results weren't
> what I expected.
>
> It turned out that the build took 2 minutes of elapsed time
> in both cases. However, the 64-bit build took 12 seconds less
> of usermode time, and 12 seconds more of system time. Go
> figure.
>
> --
> Jon Forrest
> forrest@ce.berkeley.edu
> Computer Resources Manager
> Civil and Environmental Engineering Dept.
> 305 Davis Hall
> Univ. of Calif., Berkeley
> Berkeley, CA 94720-1710
> 510-642-0904
>
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-- 
-     _____/     _____/      /           - Jonathan Loran -           -
-    /          /           /                IT Manager               -
-  _____  /   _____  /     /         Space Physics Research Group     -
-        /          /     /      Space Sciences Laboratory, UC Berkeley
- ______/    ______/    ______/  (510) 643-5146 jloran@ssl.berkeley.edu
                                          AST:7731^29u18e3
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