Windows 8 Registered I/O Example UDP Servers

I’ve been looking at the Windows 8 Registered I/O Networking Extensions since October when they first made an appearance as part of the Windows 8 Developer Preview. Whilst exploring and understanding the new API I spent some time putting together some simple UDP servers using the various notification styles that RIO provides. I then put together some equally simple UDP servers using the “traditional” APIs so that I could compare performance.

RIO API demonstration

The examples are simple in that they do the bare minimum to demonstrate the APIs in question but they are configurable so that you can tune them to the hardware on which you’re running them. You can run them to compare the maximum speed at which you can pull UDP datagrams off of the wire using each API and then adjust the examples so that they do a specific amount of “work” with each datagram to simulate a slightly more realistic scenario.

Simplified error handling

Error handling is limited, we display an error and exit the program, but we don’t skip error checking, all API calls are checked for errors. The examples are each stand alone but can share two common header files. The first, Constants.h, contains all constants that are used to tune the examples. The second, Shared.h, contains inline helper functions which hide some of the complexity and allow the individual example programs to focus on the area of the API that they’re demonstrating.

This is the index page

I will be blogging about the construction of the various examples over the next few weeks and updating this entry as an index page for all of the examples. I’ve listed the examples that I’ll be talking about and I’ll link to each blog post as they go live. Once I’ve presented the RIO examples I’ll present the more traditional examples and finally some performance comparisons.

RIO server examples

• RIO Polled UDP - A server which uses a single thread and a tight loop to poll for RIO completions.
• RIO Event Driven UDP - A server which uses a single thread and event driven notifications to handle RIO completions.
• RIO IOCP UDP - A server which uses a single thread and I/O Completion Port notifications to handle RIO completions.
• RIO IOCP MT UDP - A server which uses a configurable number of threads and I/O Completion Port notifications to handle RIO completions.

Traditional server examples

• Simple Polled UDP - A server which uses a single thread and a tight loop to poll WSARecv() for datagrams.
• IOCP UDP - A server which uses a single thread and I/O Completion Port notifications to handle overlapped WSARecv() completions.
• IOCP MT UDP - A server which uses a configurable number of threads and I/O Completion Port notifications to handle overlapped WSARecv() completions.

A simple UDP datagram traffic generator

• Simple UDP traffic generator - A client which uses a single thread and a tight loop send datagrams using WSASendTo(), this easily saturates a 1000BASE-T, 1Gb ethernet connection.

Test scripts

• Test scripts - These simple scripts create performance counter logs and run the test servers.

Performance Test results

• The first tests - Where we compare the simple polled traditional server with the polled RIO server.

Join in

Comments and suggestions are more than welcome. I’m learning as I go here and I’m quite likely to have made some mistakes or come up with some erroneous conclusions, feel free to put me straight and help make these examples better.

Code is here