Real-Time OS

[Christian]

On Sat, May 20, 2000 at 11:14:13PM +0800, Nick Bannon wrote:
 
> Yes - it's the _guarantee_, rather than the speed that's at issue.
> A RTOS lets you build a system in which you can _guarantee_ that a
> particular action will take no more than a given time, even in the
> worst case.

Isn't it also the resolution/granularity of the time measurements?  For
example, you can use POSIX real-time scheduling under Linux but the
granularity is up to +10ms out because of the scheduler.  For many
real-time applications 10ms is far too coarse.

> On some systems (like Irix) you can say that some particular process is
> a "real-time" process, which means that if it wants to hold onto the
> CPU, it can. This can be useful for, say, CD burning - it reduces the
> chance of a buffer underrun. However, the system will freeze whenever
> it has to wait for the CD, and if the RT process is buggy and crashes,
> it can take the machine down.

Linux does this too.

Regards,

Christian.