On Tue, 2006-02-21 at 19:30 -0600, Jan Depner wrote:
> On Tue, 2006-02-21 at 15:28 -0500, Lee Revell wrote:
> > On Tue, 2006-02-21 at 13:19 -0600, Jan Depner wrote:
> > > There's a bunch of information on that on my site (albeit outdated).
> > > Tuning the disk drives is a must and it *will* help but there are
> > > instances where the disk drive is busy and you can't get to it no
> > > matter
> > > how well tuned it is. I prefer to minimize any chance of that. You
> > > have to remember that unless you're running RTLinux or VXWorks (or DOS
> > > or VMS) you're not running a hard real time system. Shit happens.
> > >
> >
> > The -rt kernel with fuill preemption actually is a hard real time system
> > (no one claims it is in the same league of reliability as QNX or
> > VXWorks, yet...) - it should be able to guarantee response times.
> >
>
> While I agree that it's very good it's not hard real-time. It can't
> do guaranteed 15 microsecond interrupt response. It is a very good soft
> real-time system.
>
Hard RT is not about what the response time is, it's about whether you
can guarantee to make some arbitrary deadline, which the -rt patch can
theoretically do (I say theoretically because you still would have to
audit a limited set of code paths for RT safeness).
> > Of course the best RTOS in the world won't save you from apps that do
> > disk or GUI stuff in a non RT safe way, or from buggy ACPI
> > implementations that disappear the CPU out from under the OS for
> > milliseconds...
> >
>
> Yup. I hate it when that happens ;-)
>
>
Received on Sun Feb 26 20:18:37 2006
This archive was generated by hypermail 2.1.8 : Sun Feb 26 2006 - 20:18:37 EET