Slashdot Mirror
New Thunderbolt Revision Features 20 Gbps Throughput, 4K Video Support
hooligun writes "The next-gen Thunderbolt tech (code-named Falcon Ridge) enables 4K video file transfer and display simultaneously in addition to running at 20 Gbps. It will be backward-compatible with previous-gen Thunderbolt cables and connectors, and production is set to ramp up in 2014. An on-stage demo with fresh-off-the-press silicon showed the new Thunderbolt running 1,200 Mbps, which is certainly a step up from what's currently on the market."
So, will we see OEM Windows PCs come by default with Thunderbolt ports? Or is this another fantastic, magical, extraordinary Apple Inc. exclusive?
I do 10GbE drivers, and the previous generation of tbolt did not really offer 10Gb/s of usable bandwidth to PCIe devices, it was more like 8Gb/s:
If you recall, tbolt muxes PCIe and Display Port. On the PCIe side, the thunderbolt bridge passed 2 lanes of Gen2 PCIe through to devices. Since Gen2 is "5GT/s" per lane, you'd think you'd have 10Gb/s. But not really, as "10Gb/s" does not take into account PCIe overhead, which can be about 20% of the data transfer rate. So on the original "10Gb/s" thunderbolt, you were lucky to get 7Gb/s transfer rate from 10GbE NIC, once you also add in network protocol overheads.
Having a bus-constrained NIC leads to all sorts of weird problems when receiving data.. With flow control disabled in combination with bursty transfers, you often see far less than the 7Gb/s peak, as TCP hunts around to find the constraint and recover from frequent packet loss events.
It sounds like they've built the new part from 2 lanes of Gen3 PCIe, which should be good for ~16Gb/s of usable bandwidth. This is a very welcome change, as 16Gb/s should be enough for a single-port 10GbE NIC running at full speed, and a disk controller talking to a fast SSD or an external RAID array that can deliver ~750MB/s (bytes) of I.O.
Just don't try to use a bonded 2 port 10GbE NIC, or you're back at the bandwidth constrained problem.