RTEMS4.7 PowerPC clock (was Re: IRQ latency)

[Kate Feng]

Peter Dufault wrote:

> On Aug 10, 2005, at 8:36 PM, Kate Feng wrote:
>
> >
> > Peter Dufault  wrote :
> >
> >
> >
> >> Me? No, I *never* disable interrupts! (well, almost never).
> >>
> >>
> >
> > Yes, it's better to limit it to the minimum.
> >
> >
> >
> >> But seriously, no I didn't disable interrupts. I'm a firm believer in
> >> lock-free systems, which to my thinking means trying to push the
> >> locks down to the hardware level.
> >>
> >>
> >
> > I  am not sure  if you will get an  accurate timestamp in you test as
> > you mention  that you use  system clock, especially  under the heavy
> > load.   Anyway,  Till should make a  conclusion about  its pedigree.
> > He is the one who made the enhancement  in RTEMS4.7 PPC
> > shared port.
> >
> >
> >
>
> Kate asked me off-list if I'd disabled interrupts in my timings, and
> this is how I responded.  I'd have been less tongue-in-cheek on-list,
> but it's OK with me for anyone forward my emails unless I say not to.

My apologies.  I  did'nt sense the  tongue-in-cheek that I thought it's OK
to forward  it for discussion.    I  have tried to stay quiet  waiting for
a
conclusion since Feb..  so that I can move on to RTEMS4.7.  However,
I did'nt see it implemented in the RTEMS4.7 yet that I am not  sure what's
going on.

>
>
> I use the 64-bit Power-PC time counter, not the system clock, so the
> timings should be very accurate.

Sorry, I thought you used the decrementer.  -- Kate

>
>
> In an earlier posting I said that if something resets that time
> counter I'm in trouble, but I'm 99.99% sure that the time counter is
> left alone.
>
> Till will tell.
>
> Peter