Windows 8 Registered I/O Performance - finally using a full 10 Gigabit link...

As I mentioned back in March I’m now doing some RIO performance testing with a 10 Gigabit Ethernet link as I couldn’t push my test server hard enough with multiple 1 Gigabit links. This involves 2 Intel 10 Gigabit AT2 cards connected directly to each other. One of the cards is in our test server and the other has been tried in various other pieces of test hardware in an attempt to ramp up the bandwidth usage for the RIO tests. Unfortunately driving one of these network cards to its limits takes quite a lot of CPU and also requires that the card is in a PCI Express slot with x8 capabilities; our other test hardware, being slightly older, has plenty of slots capable of taking the card, but only a relatively low spec build machine had any of those slots wired up as x8. This left me in a situation which was fractionally better than teamed multiple 1 Gigabit links but nowhere near the full potential of the 10 Gigabit link.

I’ve just finished building a new developer workstation with an Asus P9X79 WS Intel X79 motherboard and a 3.20GHz Core i7 3930K processor. We now have the bus bandwidth and the processor power to push the link and stress the server nicely. At 50% link saturation we’re running at around 10% CPU usage on the source machine (1 of the 12 cores pegged at 100% by the simple UDP traffic generator that we used in the earlier tests). On the test server we are also using around 10% CPU for my most complicated RIO IOCP design.

Rough results for this 50% loading of the link give 350,000 datagrams per second processed by a traditional IOCP UDP server with 8 threads as against 450,000 datagrams per second from a naive RIO IOCP server design and 920,000 per second from a more complicated design. Pushing the loading to 75%, by running the traffic generator twice, shows no improvement in datagram processing speed from the traditional design but the complicated RIO design moves up to 970,000 per second. These results should be taken with a pinch of salt as I haven’t had a chance to check them over and test more thoroughly. I’ll present the server designs in the same way that I’ve presented the previous designs when I publish the full results.

Looks like I’m finally in a position to see what RIO can really do…

Code - updated 15th April 2023

Full source can be found here on GitHub.

This isn’t production code, error handling is simply “panic and run away”.

This code is licensed with the MIT license.