At 02:05 PM 10/30/2006, Roland Dreier wrote: > Hal> So rate = speed * width ? > >Yes, you should see the right think on DDR systems etc.
Strange. Bandwidth = signaling rate * width. This of course is raw bandwidth prior to encoding, protocol, etc. overheads which will derate the effective application bandwidth minimally be 20-25%. If the goal is provide a true indication of the maximum peak bandwidth that an application might see, then stating 10 Gbps for an IB x4 SDR is clearly a misrepresentation and out of alignment with other networking links such as Ethernet which customers understand its bandwidth to be minimally after the encoding, etc. is removed from the equation. The perpetual trend by marketing to use 10 Gbps IB as equivalent to 10 Gbps of application data is actually detrimental not beneficial when it comes to customers. It inevitably leads to the question of why the application is not achieving the stated bandwidth, i.e. why it is say 700-800MB/s theoretical peak for a x4 while a 10 GbE is 1 GB/s peak. So much marketing hype has gone forward already. I realize I'm tilting at windmills but if you are to provide a tool that is supposed to project the maximum bandwidth possible and given the goal of OFA is to provide as much conceptual commonality with existing network stacks / links, then it would be beneficial to have this move towards a much more apple-to-apple communication of information. I know it would certainly help with having to repeatedly explain why IB 10 Gbps is not the same as 10 GbE to customers and analysts. Mike _______________________________________________ openib-general mailing list [email protected] http://openib.org/mailman/listinfo/openib-general To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general
