Re:[myrinet] Re: Using multiple Myrinet in parallel?

>On Tue, Aug 28, 2001 at 03:55:19PM +0800, geoge_zhang wrote:
>
> Careful, some systems have 2 or more distinct primary PCI buses (Compaq's
> AlphaServer ES40, DS20E, AS4100, etc).  So it is possible to have more than
> one Myri adapter in a box.  The questions are legitimate.  Any takers on the
> original message, I have been asked this same question recently from a
> potential research customer.  

   Our platform is a PC cluster connected with Myrinet. Each PC has four Intel 
XEON processors running LINUX with 66Bits/66MHZ PCI bus.
  I'm not very sure about the characteristics of PCI buses, does our PC cluster
platform has 2 or more primary PCI buses, which makes it possible to benifit from
using multiple myrinet cards ? Any advice about our idea is appreciated.

>Myrinet already supports multiple cards, even on multiple PCI busses
>where they exist. However, it doesn't automagically use the cards in a
>useful fashion. That would require either some minor hacking
>(modifying mpirun, for example, to have certain neighbors use certain
>cards) or moderate hacking to the internals of gm (transparent
>multiplexing).
>
  Since the perfomance of GM for a single myrinet card saturates a PCI bus 
as is said, then does it means that Myrinet's support for multiple cards means nothing ? As the peak performance of GM has been limited by the PCI buses,
it maybe an approach to increase the performance GM.  

Best regards
Geoge Zhang
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