Hi Victor,
Tried it on RTLinux 2.3/Linux 2.2.14. Exactly the same effect. If you
cat /proc/apm, the jitter jumps out to ~ 7 miliseconds.
Regards, Stuart.
Stuart Hughes wrote:
>
> Hi Victor,
>
> The version was RTAI-1.3 and Linux 2.2.14 on top of a RedHat 6.2, the
> machine was an Inspiron 7000 with bios power saving disabled (disk power
> down etc) but with APM support in the Linux kernel. I'll be running the
> same test on RTLinux 2.3 and post the results.
>
> Regards, Stuart.
>
> [EMAIL PROTECTED] wrote:
> >
> > Stuart:
> > What's the version information on this?
> >
> > On Thu, Jun 01, 2000 at 11:39:29AM +0100, Stuart Hughes wrote:
> > > I always knew that APM was bad news for realtime (as it does cli etc),
> > > but I was not aware that gettting the APM info from proc was also a
> > > disaster. While running some jitter tests that normally give +/- 7usec
> > > on a quite machine, I did a cat /proc/apm, this pushed the upper limit
> > > to 7milliseconds. So beware, just running a little X helper like xapm
> > > (now disapeared from the latest redhat) will cause your realtime to
> > > miss-behave.
> > >
> > > Conclusion: If you have APM enabled at all, beware as your real-time
> > > programs can go out to lunch (even things as innocent as plugging in the
> > > power cable to your laptop).
> > >
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