3 ms·
What's wrong with PCIe? The devices are ubiquitous. It's point-to-point, allowing for device to device connectivity. We have external PCIe enclosures and cables
by sargun 10y ago
What's wrong with PCIe? The devices are ubiquitous. It's point-to-point, allowing for device to device connectivity. We have external PCIe enclosures and cables. We have a healthy set of PCIe switches.
This is similar. It's also point-to-point, and it has an external story. Skimming the spec, they've even thought about higher latency (200ns) links, and optical. Even with these advantages, I'm unsure how it'll work due to the lack of IP available as compared to PCIe.
Interesting, though. Will be fun to see it play out. It bums me out a little bit though that POWER isn't easily available yet.
- eeks 10y agoPCIe is still rather slow. A single-packet transaction on PCIe costs 120ns. The lack of IP is the reason why P8/CAPI stuck to PCIe. In the original design, CAPI was to simply reuse the PCI link layer, not the transaction layer. With a cache-coherent system based on PCIe, especially when the coherency layer is set at L3 like on POWER8, you are looking at ~500ns latency for a single cache line. This kind of latency is just too much for many applications.