CAPI on POWER systems
April 29, 2014
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One of the biggest and the most spectacular news which I’ve experienced on my last residency, was the completely new technology called Coherent Accelerator Processor Interface (CAPI). I was in big shock after a meeting with with the project leader. It sound for me as the holy grail for all I/O bandwidth and latency problems.
So far, this technology is not advertised so much, and people do not comment it yet. I think mainly because not many of us realize how it can benefit. The thing is that IBM puts completely new interface directly to the P8 chip. CAPI brings a layer which allows an external adapter to communicate directly with the same memory addresses what the processors use. Therefore, a bottleneck such as PCI host bridge does not make a problem anymore. Moreover, with CAPI no drivers in an Operating Systems are needed, so another barrier is gone.
Unfortunately, for the present day there are no adapters which can fully use this interface, but it’s only matter of time. I’ve heard that IBM is trying to make CAPI an infrastructure standard such as the SR-IOV, or the PCIe. Which will open the technology for third party companies.
This will be absolutely amazing thing, once it get fully functional. We can have very fast I/O controllers or GPUs adding on the external cards, which will accelerate scientific application.
I can imagine that in couple of years even heavy gamers might use this interface in their home PCs.