🚀 go-pugleaf

fr...@genesis.demon.co.uk (Lawrence Kirby) writes:
>That seems excessively high, what are the conditions that generate that?
>I've done some detailed serial port load testing (though clearly not with
>Descent) Under SCO Unix. If you run a 16550A serial port at a
>*continuous* 38400bps the system load on a 486/33 is about 5%. (2 player)
>Descent uses a vastly lower bandwidth than that so I'd venture it should
>generate about a 1% overhead or there is something wrong with the driver.
>With an 8250/16450 you could see about 10% overhead.

The difference is that the current serial driver in Descent uses a polled
output routine rather than an interrupt driven one.  If we used interrupt
driven serial output I think your figures would be just about right.

As to why Descent uses polled output, it has to do with the Greenleaf
serial I/O lib used in the game.  Probably future Descent games will
have a more efficent serial send routine utilizing interrupt driven output.
----
Rob Huebner