RDRAM vs SDRAM redux

[Greg Lindahl]

On Wed, Nov 07, 2001 at 11:26:39AM -0500, Robert G. Brown wrote:

> Life continues to get more puzzling all the time.  We are working out
> final configurations for a mixed purchase of P4's and Athlon XP's.  Or
> so I thought when I started to review the hardware alternatives this
> morning. I'm basically getting ready to update a quote from three months
> ago but the world has of course changed substantially in the meantime.

What you're lacking is a good understanding of your code, cpu
vs. memory bandwidth. One way to explore that is to play with your
BIOS settings to artifically lower your STREAM bandwidth. Run your
code and STREAM both ways, see what happens.

> The Athlon update was fairly easy.  It looks like the KT266A chipset is
> probably the one of choice for a single CPU solution

If you don't mind terrible PCI performance, yes.

> The P4's are much more difficult because there are now SDRAM chipsets.

Right. And if you knew your code's dependence on stream, you'd be all
set.

> There is also no clear indication on whether using
> an SSE compiler with the XP makes a difference -- does the XP support
> SSE1 and/or SSE2 instructions?

If I recall correctly, the XP has SSE1, and the MP has SSE2, or at
least more than the XP has.

greg