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 There's a bunch of information on that on my site (albeit outdated).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 ;-) > >
