January 17, 2007 8:55 AM PST
PCI Express turns 2.0
As expected, PCI Express turned 2.0 by fiat of the PCI Special Interest Group, the industry cooperative that governs the specification and announced the new version Monday.
PCI Express--a modernized sequel to the original PCI (Peripheral Component Interconnect) that spread to essentially every server and PC since it was introduced in the 1990s--can transfer 2.5 gigabits per second on each wire, pin or other electrical connection called "lanes" between a computer and a plug-in device. PCI Express 2.0 doubles that rate to 5Gbps, and as with the existing PCIe, multiple lanes can be ganged together.
PCI Express (PCIe) 2.0 probably will first arrive about a year from now, said Al Yanes, chairman of the PCI SIG.
"As with PCIe 1.0, we expect the graphics guys to be the first adopters of PCIe 2.0," Yanes said. The technology also will be used in cards for high-speed networks including InfiniBand, Ethernet and Fibre Channel, he said.
The PCI Express 2.0 speed isn't fixed, though. For one thing, the new version is backward compatible, meaning that older, slower devices can plug in. For another, an extension to the specification permits hardware to control the speed at which a PCI connection runs.
Because management software will be able to control the link speed, computer makers will be able to lower power when the full PCI transfer speed isn't needed, Yanes said. The move is one example of the computing industry's attempt to moderate excessive power consumption and resulting waste heat problems.
Anther improvement under development is the ability to support power-hungry graphics cards. And a feature called Input-Output Virtualization is designed to make it easier for multiple virtual machines, each with its own operating system, to share PCI devices such as network cards.
Another option: The PCI Express Cable specification will let PCI devices be connected not just with plug-in slots but also with standardized copper cables as long as 10 meters with data transfer speeds of 2.5Gbps per line. The technology is suited for tasks such as adding an input-output expansion module housing numerous network cards to a higher-end server.
The cable specification should be done this month, Yanes said. Different components of the virtualization work will trickle out as 2007 progresses, and Yanes said, adding, "I expect to see the IOV spec go live later this year."
Finally, a longer-term effort, code-named Geneseo, will let coprocessor cards such as graphics or encryption accelerators be tightly connected to central processors.
Regarding Geneseo, "We have only taken the first step to begin looking into the future possibilities with the technology," Yanes said, with the PCI SIG's protocol and software group examining the idea and scheduled to deliver a status update at a PCI conference in the second quarter of the year.