by Anton Shilov
06/24/2010 | 11:48 PM
PCI special interest group (PCI SIG) will only start compliance tests of PCI Express 3.0 (PCIe 3.0) products in early 2011, a year later than expected originally, which naturally leads to delay of the actual PCIe 3.0 deployment to 2012. However, members of the group, who produce chips and add-on-cards that use PCI Express interconnect, are not worried about the delay since bandwidth increases are not needed just now.
“I do not think we have lost any opportunities. Our member companies are OK with this timeline. 40Gb Ethernet is not here yet, and is still being developed by our member companies,” said Al Yanes, president of the PCI SIG at a meeting with press at the annual PCI SIG Developer's Conference, reports EETimes web-site.
The third-generation incarnation of PCI Express has numerous advantages over existing bus specifications. The PCIe 3.0 will operate at 8GT/s (8.0GHz) speed, will have different electrical models and will move to 128-bit and 130-bit encoding schemes (from 8- and 10-bit schemes). In 2008 Advanced Micro Devices and Hewlett Packard proposed a number of extensions for PCI Express 3.0. One of the extensions is protocol multiplexing, a feature that would allow chips to dynamically switch between seven different protocols in addition to PCIe using the shared set of pins. This would allow creation of chips that would be compatible with PCIe, HyperTransport, QuickPath Interconnect, Ethernet and other buses at the same time. Another extension is called lightweight notification and would allow co-processors or peripheral chips to talk to each other through system memory using a PCIe transaction without interrupting a host processor. For example, an Ethernet switch could respond to commands to encrypt and decrypt specific data packets while a host processor is inactive.
“It is a trial-and-error process – that is why we hate to give timelines. One day we have one company with results saying we can meet the spec, and another day someone says, 'did you consider acoustics, or thermals or humidity and how these things impact the design. It is a very lively environment where people come in with all sorts of data and some of it does not align, so we have to go back and find out why, find the mistake, align everyone and move forward," explained Ramin Neshati, chair of the PCI SIG's serial communications work group.
PCI Express 3.0 and its improved bandwidth is mostly needed by 100Gb and 40Gb Ethernet cards, high-end graphics cards, next-generation Infiniband interconnects, ultra high-end solid-state drives and other bandwidth-intensive applications. Still, at present there are no such cards that demand something more than PCI Express 2.0 x16 can offer, which is about 8GB/s.
In case PCI SIG starts testing of PCIe 3.0 products for compliancy in early 2011, it will still take at least a year before the standard will actually get adopted. In order to install a 100Gb/s Ethernet card into a server, not only an Ethernet controller that supports PCI Express 3.0 is needed, but also a server-class core-logic set that supports the new interconnection.