You'll see that a large portion of that single-processor IRIX sample code exists only to work around the lack of IRIX process scheduling guarantees. If you could be guaranteed that your process would run, say, every millisecond, then there would be no need to schedule sony commands for transmission far in the future and receive responses which are potentially from far in the past. On multi-processor SGI systems, including Onyx, Challenge, Onyx2, and Origin, you can do this. SGI lets you dedicate one or more processors to real-time tasks. But deck control rarely saturates the serial port, and the port runs at only 38400 baud.
Low latency is much more important.
0 is a good value to use for minimum latency. You don't want this for deck control. This turns your serial port into a raw byte pipe. You only need this one some of the high-end platforms, as described in Getting 422 in and out of Your SGI . We're sure there are hundreds more tips that we could put into this page.