My shallow understanding of big servers and IBM Z series amounted to "lots of dedicated IO processors". Seems like "mainstream" caught up with big blue.
Sort of. It ebbs and flows, generally more maintainable to do more in CPU/kernel and less in HW/firmware for PCs and of course price runs the market so there's a race to do less. Part of the mainframe price tag is getting long term support on the whole system stack, whereas PC vendors actively abandon stuff after a few years. That is a big risk for something like TCP offload engine.
Every mainframe interface is basically an offload interface.. "computers" DMAing and processing to the CPs and each other. Every I/O device has a command processor, so it can handle channel errors and integrated pcie errors in a way PCs cannot.
A PC with Chelsio NICs doing TCP offload with direct data placement or RDMA as well as Fiber Channel storage would be mini/mainframe-ish.
Pretty much. Mainframes have been very I/O oriented from the start. Channel I/O (more or less DMA) with dedicated channel programs and processors can be very high-throughput.
Also I suppose it frees the logic processors from all IO (caching too?) related processing and allow for fancier strategies downstream .. (all guess fest)
Every mainframe interface is basically an offload interface.. "computers" DMAing and processing to the CPs and each other. Every I/O device has a command processor, so it can handle channel errors and integrated pcie errors in a way PCs cannot.
A PC with Chelsio NICs doing TCP offload with direct data placement or RDMA as well as Fiber Channel storage would be mini/mainframe-ish.