Re: how to analyze clock drift

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On Mon, 24 Nov 2014 12:24:15 -0500, Dennis Lee Bieber wrote:

> On Mon, 24 Nov 2014 09:44:39 +0100, "Dmitry A. Kazakov"
> <mailbox@dmitry-kazakov.de> declaimed the following:
> 
>>Setting THREAD_PRIORITY_TIME_CRITICAL blocks practically everything (except
>>for drivers).
>>
>>However I doubt that background processes or services are the problem when
>>waiting for 10 or 5ms
>>
> 	Many moons ago I had a task using a GFE W98 (!) laptop [needed to be
> W9x to allow direct access to the parallel port].

Windows 98 cannot be compared with NT.

> Wasn't a timer situation
> -- it was more a busy wait since the main timing control was obtained from
> an external (1KHz as I recall) clock to a signal pin on the parallel port.
> The task required writing 6-bits on each clock transition (I forget if
> L->H, or H->L) -- the 6-bits representing three RS-422-style balanced data
> lines... 

You should have written a proper driver for this with interrupts and
deferred I/O.

BTW, TIME_CRITICAL blocks even deferred I/O processing, if I correctly
remember. Windows internals are not that bad as painted.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de