Ok here are more details about it.
The multitasking system in call MultiTask from USSoftware. The code I am
running is simple
The first command - after saving a few registers which I need to do - in
the interrupt code is writing to a flip-flop on the board which resets
the interrupt line. Because of this I only have to watch this irq 9 line
with an oscilloscope. That's where I found a 25 us reaction time. I know
it takes about 0.8us to write to the flip-flop because its memory
mapped.
BTW: A write to a regular io port on an ISA board takes me about 1us (I
use two out instr., one with 1 and one with 0 and there is an 1us puls
on the parallelport out, which I have used). I can't tell how long the
part of writing the 1 to the port is. because it's an average of set and
reset.
I want to get a feeling if most of the time is wasted in the os or if
this is the limit - or about the limit of the processor together with
the ISA environment.
The system uses Pharlab extender and runs in 32 bit mode
Heinz
( I would like to do it with RTL or RTAI, but you know: never change a
running system!)
> -----Original Message-----
> From: Paolo Mantegazza [SMTP:[EMAIL PROTECTED]]
> Sent: Tuesday, May 16, 2000 4:58 AM
> To: Heinz Haeberle; [EMAIL PROTECTED]
> Subject: Re: [rtl] interrupt reaction time
>
> Heinz Haeberle wrote:
> >
> > Hi folk,
> >
> > I work on a different realtime system and figured out, that te
> interrupt
> > reaction time
> > on a isa-system with a 486 66MHz is about 25us.
> >
> > What are you thinking about this value?
>
> Before saying anything I would like a more detailed explanation about
> what you mean for reaction time: just getting it acknowledged after it
> has been electrically triggered or till the ending of its processing.
>
> If you refer to just getting it acknowledged, the above figure is
> likely
> to be a worst case under UP RTL/RTAI.
>
> Ciao, Paolo.
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