How to *use* multiple GigE adapters into a single PC

Richard Sharpe rsharpe at
Mon Jul 22 08:36:02 GMT 2002

On Mon, 22 Jul 2002 bdavids1 at wrote:

> ServerWorks Grand Champion HE chipset supports dual Pentium 4 
> processors.  There's 3.2 GB/s to each proc, and with quad-interleaved 
> DDR memory, you've got a 6.4 GB/s memory bandwidth.

Hmmm, that is the way to go, by the sounds of it.
> Compaq's DL530 and ML580 seem to fit what you're looking for.  They 
> have 4 100MHz 64bit PCI-X busses.  The ML580 has 7 64-bit PCI-X slots.
> For a single processor system, I think the FSB becomes the bottleneck, 
> at 3.2 GB/s (that's GigaBit, right?).  So that would be 400 
> MegaBytes/sec.  (4) 117 MegaByte/sec connections would be 468 MByte/sec.

Hmmm, I think that is 3.2 MegaBytes a sec. Even 133MHz FSB with 32-bit 
transfers is above that.

> How does DMA fit into all of this?  Can data be written/read to/from 
> disk into a buffer via DMA, and thus not eat up FSB bandwidth?  Same 
> question for the networking.  I know, that's more a question of what 
> the drivers do - I'm just writing down some of the questions going on 
> in the back of my head...

In my case, on the driver side the data never goes to disk. It is made up 
on send and thrown away on write. On the server side, it tends to come out 
of the cache on read, and goes to other machines over the network on 

> Ok, so the disk system really would be the bottleneck, unless you had a 
> really big RAM drive or most of the file requests were for data already 
> in cache.  For testing that shouldn't be a problem.

Thanks for these useful options.

Richard Sharpe, rsharpe at, rsharpe at, 
sharpe at

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