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

bdavids1 at bdavids1 at
Mon Jul 22 07:25:01 GMT 2002

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.

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.

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...

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.

Brian Davidson
George Mason University

----- Original Message -----
From: Richard Sharpe <rsharpe at>

> Hi,
> On Friday I managed to get a single PC to suck down something like 
> 117MB/s 
> from a NetApp F840 using cifs-load-gen.
> The only PC-like platforms that I can think of that would be able 
> to 
> [ab]use all the bandwidth available in two or more GigE adapters 
> would be 
> things like the AMD 760MPX-based mobos or some Intel mobos with 
> multiple 
> 64-bit 66MHz PCI slots. Can anyone point to any others?
> I know that Intel provide dual GigE channels on one card, so this 
> would be 
> a way to put four into one PC, but I am not sure you would have 
> much 
> memory bandwidth left over.
> I want to find a way to test the multi=interface stuff I want to 
> put into 
> cifs-load-gen and find where its limits are from a load-generation 
> point 
> of view.

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