Re: 64-bit vs. 32-bit Computing

The FreeBSD mailing lists report that an amd64 (aka x86_64) OS will tend
to be slower than the 32 bit version. The reason? It takes twice as long
to memcpy pointers!

There's been talk about building binaries that use 32 bit pointers but
take special advantage of other features (more registers, etc) but
nobody's actually done it yet (in the FBSD world).

I've been using 64 bit builds in situations where I want more address
space than 4GB.

Mike

On Apr 12 at 17:18, "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.

------------------------------------------------------------------------
The following was automatically added to this message by the list server:

For information about Micronet, including subscribing to
or unsubscribing from its mailing list and finding out
about upcoming meetings, please visit the Micronet Web site:
<http://micronet.berkeley.edu/>.
Received on Thu Apr 13 09:15:15 2006