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List:       linux-rt
Subject:    Re: [rtl] differences over 2.2a & 3.0
From:       Stuart Hughes <stuarth () lineo ! com>
Date:       2000-11-30 16:55:18
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Craig Ireland wrote:
> 
> Hello,
> 
> I have already emailed this list regarding this problem but I put down the
> limited response to some trivial oversight on my part.
> 
> I have problems running a program under rtlinux22 bu recently recompiled it
> under rtlinux30 and the problem disappeared.  However, another, more serious
> (from my viewpoint), problem emerged.  This has led me to believe that
> perhaps it is not entirely my causing.
> 
> Basically, my problem under rtlinux22 is that a thread that runs
> continuously for some period ~10seconds and then halts and is deleted,
> causes linux to behave erratically, and responsive only to the keyboard.  ie
> mouse is disabled, floppy access impossible, a crash on shutdown.  this
> persists until my module and rtl_sched is uninstalled.  I have not disabled
> any interrupts.  I presume that the lines in cleanup_module of rtl_sched are
> what restore the system to its normal state.
> 
> Under rtlinux30, this doesn't occur.  However, the output of my module (a
> parallel port digital waveform) can waver in duration by up to 10us for a 20
> us pulse.  This is far in excess of the 1us jitter of rtlinux22.  The only
> calls in this code are to gethrtime(), rtl_delay, and outb().  I do not
> understand why there is any difference to rtlinux22.  The timing of the
> pulse is all internal and unrelated to the scheduler.
> 
> I would appreciate it if somebody could point me in the direction of a
> solution, or if anybody would be willing to look at the code (it is very
> short).  Could it be that I've set up RTLinux poorly?
>

Hi Craig, 

The jitter you get is well within what would be expected.  I don't
understand why you're old setup gave +/- 1usec, to me this was probably
a result of a system with no load.

Regards, Stuart
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