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Re: Re[2]: PCIX confusion

From: EM1897@xxxxxxx
Date: Mon, 14 Mar 2005 18:54:01 EST

In a message dated 3/14/05 4:34:39 PM Eastern Standard Time, gaml@xxxxxx 
Eac> Try to pay attention, Tom. There are no pci-E x16 ethernet
Eac> cards. 

:Quite possibly because Gigabit Ethernet needs 1gbit, but PCIe x1
:deliver 2.5gbit/s in BOTH directions.

Gigabit needs 2Gb/s (it is full duplex), but as always it would depend
on what you're doing. With a router or network appliance, where
there is little disk access, a single device on the PCI-X bus will
outperform (and  have more raw bandwidth) that a PCI-E device.
Again, its one of those things you can theorize about all you want, but
you have to do some testing to see how it plays out in the real
world. Realistically, most people using gig cards aren't passing 
anywhere near a gig, and if they are passing say 250Mb/s combined, 
there is little contention on an 8Mb/s bus. As long as you have several
times what you need, its better to be faster than dedicated, IMO, 
at least from the tests I've done. The problem with PCI is when
you reach higher pcts of saturation (which is why PCI-X is so
important for ethernet when you're passing more than say 50Mb/s).

I find it interesting that when Matt and Joerge called PCI-X "bleeding
edge" and that there was no hardware, there was not a peep from
the peanut gallery. But now you're all saying how great PCI-E is, 
when the truth is that PCI-E is bleeding edge, and there really is
a limited understanding of it, and limited hardware available. 
Personally, I need to do a lot more testing with it before I use
it for anything commercial, thats for sure.

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